Technical Diary

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PREFACE After a great endevor WBSEBEA has published this tech-nical diary with the profound support & contribution from different members at all level. West Bengal Engineers' Association invites valuable suggestions from our member towards enrichment of the knowledge base technical diary in the next version. Any error which has been inadvertently incorporated in this diary may be communicated to this end for future guidance. Secretary West Bengal State Electricity Board Engineers' Association

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INDEX Content 1. Year Callender 2. STD Code No. 3. I.S.D. 4. World time Chart 5. Air Distance 6. Road Distance 7. Greetings 8. National information 9. Festivals 10. Conversion facter 11. Graphical symbols. 12. Priliminaries of Tower loading concept 13. Concept of Tower foundation 14. Drawing for 220kv & above transmission system. 15. 132/220/440 kv transmission system. 16. Typical substation equipment specification 17. Typical F.L. current rating of transformer. 18. Amorphous core transformer 19. 33/11 kv substation (Indoor type) 20. 33/11 kv of substation (out door type) 21. Basic technology of functional details of transformer 22. Transformer testing 23. Transformer protection. 24. Inspection & maintenance schedule of transformer & circuit breaker 25. Maintenance scheduleof transforemr equipments. 26. Test report of transformer 27. Test report of CB 28. Significance of importance of tests of transformer oil. 29. Online reclamation of transformer oil 30. DBPC oxident for reclaimed transformer oil. 31. Mixing of transformer oil. 32. Approximate requirement of major materials for R.E. works. 33. Typical S/C data for 33/11 kv Transformer 34. Clearance 35. Gap setting 36. Relays 37. Earthing 38. Battery

Page No. 4 5 7 9 10 11 12 13 14 15 16 18 25 43 44 48 50 50 51 52 54 73 80 98 105 109 114 116 126 130 132 135 138 140 142 147 184 193

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. 39.Multiplying ftactor for calculating size of capacitor 40. Regulation constant for overhead line. 41. Transformer loss calculation 42. Surge impedence & economic loading of a overhead line. 43. Fuse wire rating 44. Cable rating 45. Current rating of motor. 46. Current rating of Almunium conductor 47. Permissible span of overhead lines. 48. Weight of materials . 49. Wattage of electrical domestic appliances. 50. Rating of electrical equipments. 51. Assessment of bills incase of L & MV consumers. 52.Conversion factor MVA. Vs. AMPS. 53. Trouble shooting of felxicom type MRI 54., Trouble shooting of Analogic type MRI. 55. Display item of ABB Meter 56. Accucheck Meter connection diagram 57. Data for civil work 58. Planning of Building 59. Salient features by WBSERC 60. VSAT Technology 61. Network security 62. Reference

202 204 205 210 211 212 218 219 224 225 228 229 232 233 234 236 238 240 243 244 246 250 254 256

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YEAR - 2006

Week

1

Monday Tuesday Wednesday Thursday Friday Saturday Sunday 1

January 2 3 4 2 3 4 5 6 7 8

9 10 11 12 13 14 15

16 17 18 19 20 21 22

5

5

6

23 24 25 26 27 28 29

1 2 3 4 5 6 7

8 9 10 11 12 13 14

July Monday 4 Tuesday 5 Wednesday 6 Thursday 7 Friday 1 8 Saturday 2 9 Sunday 3 10

11 12 13 14 15 16 17

February 7 8 15 16 17 18 19 20 21

9

10

22 29 23 24 25 26 27 28

1 2 3 4 5 6

August 18 19 20 21 22 23 24

25 26 27 28 29 30 31

1 2 3 4 5 6 7

8 9 10 11 12 13 14

15 16 17 18 19 20 21

22 29 23 30 24 31 25 26 27 28

March 11 12

13 14

7 8 9 10 11 12 13

21 22 23 24 25 26 27

14 15 16 17 18 19 20

27 29 30 31

April 14 15 16 17 18 4 5 6 7 1 8 2 9 3 10

September

1 2 3 4

5 6 7 8 9 10 11

12 13 14 15 16 17 18

11 12 13 14 15 16 17

18 19 20 21 22 23 24

25 26 27 28 29 30

May 18 19 20 21 22 30 31

1

October 19 20 21 22 23 24 25

26 27 28 29 30

31

1 2

WBSEBEA - 6

3 4 5 6 7 8 9

10 11 12 13 14 15 16

17 18 19 20 21 22 23

24 25 26 27 28 29 30

1 2 3 4 5 6

2 3 4 5 6 7 8

9 10 11 12 13 14 15

16 17 18 19 20 21 22

23 24 25 26 27 28 29

June 23 24 25 26 27

1 2 3 4 5

6 7 8 9 10 11 12

13 14 15 16 17 18 19

20 21 22 23 24 25 26

November

December

7 8 9 10 11 12 13

5 6 7 8 9 10 11

14 15 16 17 18 19 20

21 28 22 29 23 30 24 25 26 27

1 2 3 4

12 13 14 15 16 17 18

19 20 21 22 23 24 25

27 28 29 30

26 27 28 29 30 31

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STD CODE NO A Abohar 01634 Adipur 0283686 Adilabad 08732 Adoni 08512 Adoor 04734 Agartala 0381 Agra 0562 Ahmedabad 079 Ahmednagar 0241 Aizwal 0389 Ajmer 0145 Akbarpur (up) 05111 Akola 0724 Alamuru 08853-82 Alibaug 02141 Aligarh 0571 Alipurduar 03561-55 Allahabad 0532 Alleppy 0477 Almora 05962 Alur 08172 Alwar 0144 Amlapurum 08856 Amravati (MP) 0721 Ambaji 02749 Ambala 0171 Ambikapur 07774 Amethi 0536 Amritsar 0183 Anmand 02692 Anant Nag 01932 Anavatti 08184 Asansol 0341 Aska 06822 Attur 04282 Aurangabad (BR) 06186 Aurangabad (MH) 0240 Ayodhya 05276 Azamgarh 0546 B Baad Badarpur Badrinath Bagdogra Bakreswar Balaghat Balasore Balia Ballarpur Ballavipur Banda (UP) Bangalore Bankura Barabanki Baragarh Barakar Barauni (BGS) Bareilly

08386 03845 01381 0353 034667 07632 06782 0549 07174 02841 0519 080 03242 05242 06646 0341 06343 0581

Baroda (GUJ) 0265 Basti 05542 Begun 01474 Begusarai 06342 Belgaum 0831 Berhampur (Orissa) 0680 Berhampur (WB) 03482 Bhabhua 06189 Bhadarak 06784 Bhagalpur 0641 Bhandara 07184 Bhavnagar 0278 Bhawani Patna 06670 Bhilai 0788 Bhilwara 01482 Bhopal 0755 Bhubaneswar 0674 Bhusawal 02582 Bijapur 08352 Bikaner 0151 Bilaspur (MP) 07752 Bokaro Steel 06542 Bolangir 06652 Bolpur 03463 Bulandshahar 05732 Bongaigaon 03664 Burdwan 0342 Burla 066382 Buxar 06183 C Calicut 0495 Cambay 02698 Cannanore 0497 Chakdah 03473 Champa 07819 Chandanpur 06752 Chandigarh 0172 Chandipur 06785 Chandrapur (MP) 07172 Chanchal 03513 Chapra 06152 Chas 06548 Chatrapati 045685 Chennai 044 Chatrapur 06811 Chidambaram 04144 Chirala 08594 Chittaranjan 0341 Chittore (A.P) 08572 Chittorgarh 01472 Chowdwar 0671792 Chowk 02146 Cochin 0484 Coimbatore 0422 Contai 03220 Coochbehar 03582 Coonoor 0423 Cuddalore 04142 Cuttack 0671

D Dadri Dalhousie Daltongunj Daman Danapur (PT) Darbhanga Darjeeling Deesa Dehradun Dehari on Sone Deogarh Deoghar Dewas Dhanbad Diphu Dhubri Diamondharbour Dibrugarh Digha Dimapur Dispur (GH) Durg Durgapur Dwaraka

05737 01899 06562 02636 0612 06272 0354 02744 0135 06128 06641 06432 07272 0326 03671 03662 03174 0373 03220 03862 0361 0788 0343 02892

E Elnaji Eluru Erapatty Ernakulam Erode Etawah

04858 08812 0428685 0484 0424 05682 F

Faizabad Falta Faridabad Faridkot Fatehpur (UP) Ferozepur Ferozabad

05272 031722 0129 01639 0518 01632 05618

G Gadwal 08546 Gandhinagar (GUJ) 02712 Gandhinagar 0481 Gangotri 01377 Gangtok 03592 Ganjam 06811 Gaya 0631 Gazipur 0548 Ghatal 03225 Ghatkesar 084152 Giridih 06532 Goa (Punjim) 0832 Gokul 05664 Goal Para 03663 Golaghat 03774 Gorakhpur 0551

WBSEBEA - 7

Gudawal Gulmarg Guntur Gurazala Gurgaon Guwahati Gwalior

074824 01953 0863 08649 01272 0361 0751 H

Hailakandi Haflong Haldia Hamirpur (UP) Hapur Hardoi Haridar Hassan Hathras Haveri Hazaribagh Hazipur (BIHAR) Hissar Hojai Hospet Hossur Husnabad Hyderabad

03844 03673 03224 05282 0122 05852 0133 08172 05722 08375 06546 06224 01662 03674 08394 08337 08721 040

I Ichalkaranji Imphal Indore Islampur (MH) Ismailabad Itanagar Itarsi

0230 03852 0731 02342 01744 0360 07572

J Jabalpur 0761 Jagalpur 07782 Jagadishpur (Sultan)05362 Jagatpur 0671 Jaipur (Raj) 0141 Jalgaon 0257 Jallundhar 0181 Jammu 0191 Jamshedpur 0657 Jarora 07414 Jaunpur 05452 Jeypore 06854 Jhansi 05172 Jharia 0326 Jharsuguda 06645 Jhumritilaiya 06534 Jhunjhunu 01592 Jhusi 053287 Jodhpur 0291 Jorhat 0376 Junagadi (Guj) 0285 Junagarh (Orissa) 06672

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STD CODE NO K Kakdwip Kakinada Kalimpong Kalka Kalunga (RKL) Kanchipuram Kannauj Kanyakumari Kanpur Kapurthala Karimnagar Karimganj Karnal Kashipur Katihar Katni Khajuraho Khamaria Khammam Khanna Kharagpur Khurda Khurja Kisanganj Kodaikanal Kohima Kolhapur Kolkata Koraput Korba Kota Krishnagar Kundara Kurnool Kurseong Kyalanur

03210 0884 03552 017852 06619 04112 05694 04652 0512 01822 08722 03843 0184-72 05947 06452 07622 076861 05416 08742 01622 03222 06755 05738 06456 04542 04866 0231 033 06852 07759 0744 03472 04755 08518 03554 08152

L Lanka Latur Lucknow Ludhiana Lumding

0367485 02382 0522 0161 036746 M

Madhubani Madurai Mahabaleshwar Mahabalipuram Maharajgung (up) Maina (MP) Maldah Malkapuram Mangalore (PCR) Mangalore Mani Manipal (Udipi) Masauri Masur (SMO)

06276 0452 02168 04113 05523 07560 03512 0891 08534 0824 08255 08252 06129 08376

Mathura Mayapur (W.B) Merut How Midnapore Mirzapur Moghalsarai Mohara Mokama Monghyr Moradabad Moranhat Mumbai Motihari Mussoorie Muzaffarpur Muzaffar Nagar Mysore

0565 03472 0121 073183 03222 05442 05412 0171 06133 06344 0591 037543 022 06252 01362 0621 0131 0821

N Nagarcoil 04652 Nagpur 0712 Naini 0532 Nainital 05942 Nalanda 061194 Nalbari 03624 Nandikal 08159-86 Narasannapeta 08942 Nasik 0253 N awada 06324 New Bongaigaon 03664 New Delhi 011 Nizamabad 08462 Noida 0577 Nowgaon 03672 North Lakhimpur 03752 O Obaa Okha Ooty Osmanabad Ozar

05445 02892 0423 02472 02533 P

Paburia Palghat Panagarh bazar Panaje Panduah Panipath Paradeep Pathankot Patialala Patina Phagwara Pilibhit Pondicherry Portblair Pratap Garh

06847 0491 0343 08251 09113 01742 06722 0186 0175 0612 01824 05882 0413 03192 05342

Premnagar Pune Puri Purnia Purulia Puttur (Kerala)

013583 020 06752 06454 03252 08251

Q Quilandy Quilon

04961 0474 R

Raibareilly 0535 Raichur 08532 Raigarh 07762 Raipur (MP) 0771 Rajahmundry 0683 Rajgar (MP) 07372 Rajganjpur 06624 Rajgir 06119 Rajkot 0281 Rajnagar 06729 Rameswaram 04573 Ramgarh Cantt. 06553 Rajganjpur 06624 Ramnagar 05419 Ranchi 0651 Raniganj 0341 Ratlam 07412 Raxaul 06255 Rayagade 06856 Renukut 054461 Rewa 07662 Rishkesh 0136-4-11 Rohtak 01262 Roorkee 01332 Rourkella 0661 Rupanarayanpur 03444 S Sagar 08183 Sagar (MP) 07582 Sahugunj 06436 Saidapur 08473 Salem 0427 Samastipur 06274 Sambalpur 0663 Sanglo 0233 Satana 02555 Satna 07672 Secunderabad 040 Seoni 07692 Shahjhanpur 05842 Shaktinagar (VS) 054463 Shillong 0364 Sibsagar 03772 Silchar 03842 Siugguri 0353 Simla 0177 Sindri 06544

WBSEBEA - 8

Sirsa (UP) Sitamarhi Swan Sonepat S rinagar Srirampur Sundargarh Surat Suri

053289 06226 06154 01264 0194 02422 06622 0261 03462 T

Taccode Tajpur Talchar Tanuku Tezu Tejpur Thal Thane Tinsukia Tiruneveli Tirupati Tiruvellore Trichur Trivandrum Triveni Tumkur Tundla Tura Tuticorin

08253 062752 06765 08819 03804 03712 021433 022 0374 0462 08574 04116 0487 0471 03167 0816 05611 03651 0461 U

Uchagaon Udaipur Udhampur Udipi (Monipal) Ujjain Ullal Uliasnagar Unnao Upleta Utkamong (Ooti) Uttarkashi V Vadipatti Vapi Vairag Valakom Valliur Varanasi Vashi Vasko Vellore Vijayawada Visavadar Visakhapatnam Vissannapet Vizianagram Virindaban W Wardha Warora Whitefield Wokha Y Yamunanagar Yamunotri Yeotmal Z Zaheerabad

0831 0294 01992 08252 0734 0824 0251 0515 02826 0423 01374 04543 02638 02184 047570 04637 0542 022 08345 0416 0866 02873 0891 086737 08922 05664 07152 071763 08045 0386 01732 01379 07232 084512

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ISD CODE NO Country Angola Argentina

Australia

Bangladesh

Code 244 54

61

880

Belgium

32

Bhutan

975

Brazil

55

Burma

Canada Chile

95

City

Code

Luanda

2

Buenos Aires

1

Greece

Guyana

Cordoka

51

Mendoza

61

Ad elaide

8

New Amsterdam

Brisbane

7

Hongkong

Melbourne

3

Hungary

Sydney

2

Perth

9

Bogra

51

Dhaka

2

Khulna

41

Antwerp

3

Brasilia

61

Rio De Janeiro

21

Imonesia

Code 30

592

City Athens

1

Piraesus

1

Corprivertion

39

Georgetown

2

852

Hongkay

1

36

Budapest

1

Derbrecer

32

3

62

Ban jakapta

Iran

98

Asara Mashar

Iraq

Israel

Code

964

972

361 21 631 51

Baghdad

1

Babylon

30

Nastriya

42

Bethlehem

2

Mandalay

2

Jerusalem

2

Rangoon

1

Ramalla

2

Rome

6

Malano

2

1

Chawa

613

56

Toronto

416

Conception

SChina

Country

42

Itally

Japan

39

81

Kyoto

75

Santiago

2

Osaka

6

Beijng

1

Tokyo

3

Shangae

Yokohama

21

45

Colombia

57

Medlin

4

Jordan

962

Amman

6

Cuba

53

Havana

7

Kenya

254

Nairobi

2

Denmark

45

Aalborg

8

Korea (South)

82

Pusan

51

Horsens

5

Seoul

2

Naestved

3

Kuwait

965

Kuwait

-

Alexandria

3

Iebanonl

961

Grand Beirut

1

Cairo

2

Zahle

8

Egypt

20

Port Said

66

Iibya

218

Benina

63

679

Suya

1

Sabh

71

France

33

Paris

1

Sert

54

Germany

49

Berlin

30

Skopje

91

Fiji

Breman

421

Hamburg

40

Berlin

30

Macedonia Malaysia

389 60

Kualalumpur Kuantan

Maldives

WBSEBEA - 9

960

Malf

3 95

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ISD CODE NO Country Mexico

Code 52

City Acapuloo Mexico city

Namibia

264

Industira Tsumlo

Nepal Netherlands

Nigeria

Norway Oman Pakistan

Peru

746

61 671

Kathmandu

-

31

Amsterdam

20

64

234

47 968 92

51

Country Spain

Code 34

5

977

Holland New Zealand

Code

48

Sri Lanka Sudan

Switzerland

94 249

41

1747

Aukland

9

Hamilton

71

Ellington

4

Abuja

9

Lagos

1

Oslo

2

Turkey

Musoat

-

Islamabad

31

Berne

31

Geneva

22

2

Thonbiri

2

90

Anhara

41

Uganda

256

Entebbe

42

51

Undant

7

Karachi

21

U.A.E.

971

Lahore

Taiwan

Thailand

886

66

Kier

044

Abudhabi

2

42

Dubai

4

Rawalpindi

51

Sharjah

6

Areouota

54

United Kingdom

44

Birmingham Bristol

Bedzin

33

Sopot

58 -

Oradea

91

Moscow

095

St. Piherbuze

812

South Africa

Port Sudan

Bangkok

31

Somalia

51

2

Buzao

Singapore

Medani

Taipel

40

Senegal

1

4

Rowna

966

86

Taichung

Doha

Saudi Arabia

3

1

974

7

Colombo

Code

Zurich

qATAR

Russia

Badalona Vigo

Lima14 pOLANO

City

USA

1

21 272

London (Inner)

71

London (Outer)

81

Manchester

61

Alaska

907

Chicago

312

Newyork

212

Hollywood

218

Lasvegas (ny)

702

Al Khobar

3

Phladefhia

215

Damman

3

San Francisco

415

Layla

1

Washington DC

202

Dahar

-

Uzbekistan

7

Tashrent

37

Singapore

-

Venezuela

58

Carasas

2

252

Mogadisclo

1

Varacay

43

27

Cape Town

21

Vietnam

Pretoria

12

Yugos Lavia

381

Belgrade

Johannesburg

11

Zimbabway

263

..

221 65

WBSEBEA - 10

84

HB-

11

2

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WORLD TIME CHART STANDARD TIMES AT 12 NOON IN INDIA Country Abudhabi (United Arab Emirates) Addis Abada (Ethopia) Amsterdam (Netherlands) Anchorage (Alaska) Antigoa (West Indies) Athens (Greece) Auckland (New Zealand) Baghdad (Iraq) Bahrain Bandar Seri Begawan (Brunei) Bangkok (Thailand) Barbados (West Indies) Beirut (Lebanon) Bermuda Blantyre (Malawi) Bagota (Colombia) Boston (USA) Brisbane (Australia) Brussels (Belgium) Budapest (Hungary) Cairo (Egypt) Caracas (Venezuela) Chicago (Usa) Colombo (Srilanka) Copenhegen (Denmark) Dacca (Bangladesh) Damascus (Syria) Daes Salam (Tanzania) Darwin (Australia) Delhi (India) Detroit (USA) Dhahran (Saudia Arabia) Doha (Qatar) Dubai (United Arab Emirates) Entebbe (Uganda) Frankeurt (Germany) Freeport (Bahamas) Georgetown (Guyana) Hong Kong Honolulu (Hawai) Istanbul (Turkey) Jeddah (Saudi Arabia) Johannesburg (South Africa) Karachi (Pakistan)

+/-

Hours (IST)

-1½ 10.30 am -2½ 9.30 am -4½ 7.30 am -22 2.00 pm -9½ 2.30 am -3½ 8.30 am +6½ 6.30 am -2½ 9.30 am -1½ 10.30 am +2½ 2.30 pm +1½ 1.30 pm -9½ 2.30 am -3½ 8.30 am -9½ 2.30 am -3½ 8.30 am -10½ 1.30 am -10½ 1.30 am +4½ 4.30 PM -4½ 7.30 am -4½ 7.30 am -3½ 8.30 am -8½ 2.30 am -11½ 12.30 am — 12.00 noon -4½ 7.30 am +½ 12.30 pm - 3½ 8.30 am - 2½ 9.30 am +4 4.00 pm 12.00 noon -10½ 1.30 am -2½ 9.30 am -2½ 9.30 am -11½ 0.30 am -2½ 0.30 am -4½ 7.30 am -10½ 1.30 am -9½ 2.45 am +2½ 2.30 pm -22 2.00 pm -3½ 8.30 am -2.½ 9.30 am -3½ 8.30 am -½ 11.30 am

Country Khartoum (Sudan) Kolkata (India) Kingston (Jamaica) Kuala Lumpur (Malaysia) Kuwait Leningrand (USSR) Lima (Peru) London (England) Los Angeles (USA) Lusaka (Zambia) Madrid (Spain) Mauritius Melbourne (Australia) Mexico City (Mexico) Miami (USA) Montreal (Canada) Mumbai (India) Nairobi (Nenya) Nadi (Fiji) Nassau (Bahamas) New York (USA) Nicosia (Cyprus) Osaka (Japan) Oslo (Norway) Panama City (P.R.) Paris (France) Perth (Australia) Philadelphia (Usa) Prague (Czechoslovakia) Rangoon (Burma) Rome (Italy) St. Lucia (West Indies) Seychelles Singapore Stockholm (Sweden) Sydney (Australia) Tel Aviv (Israel) Tokyo (Japan) Toronto (Canada) Trinidad (West Indies) Valletta (Malta) Vienna (Austria) Washington Do (USA) Zurich (Switzerland)

WBSEBEA - 11

+/-

Hours (IST)

-3½

8.30 am -12.00 noon 1.30 am 2.00 pm 9.30 am 6.30 am 1.30 am 6.30 am 10.30 am 8.30 am 7/.30 am 10.30 am 4.30 pm 12.00midnig 1.30 am 1.30 am 12.00 noon 9.30 am 6.30 pm 1.30 am 1.30 am 8.30 am 3.30 pm 7.30 am 1.30 pm 7.30 am 2.30 pm 1.30 am 7.30 am 1.00 pm 7.30 am 2.30 am 10.30 am 2.00 pm 7.30 am 4.30 pm 9.30 am 3.30 pm 1.30 am 2.30 am 7.30 am 7.30 am 1.30 am 7.30 am

-10½ +2 -2½ -3½ -10½ -5½ -13½ -3½ -4½ -1½ +4½ -12 -10½ -10½ -2½ +6½ -10½ -10½ -3½ +3½ -4½ -10½ -4½ +2½ -10½ -4½ +1 -4½ -9½ -1½ +2 -4½ +4.½ -3½ +3½ -10½ -9½ -4½ -4½ -10½ -4½

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AIR DISTANCES DISTANCE SHOWN IN THOUSAND KILOMETERS 1 KILOMETER = 0.621 MILE Amsterdam

—

2.2

18.1

4.8

9.2

6.9

5.2

0.4

9.3 11.4 10.2

0.4 7.9 10.4 16.5 9.0

0.4 14.1

1.3

8.6 10.5 16.6 13.7 9.3

0.6

Athens

2.2

—

17.5

2.8

7.9

5.2

3.3

1.8

8.5

9.8 8.7

2.4 6.2

2.1 12.3

1.1

8.3 9.0 15.3 9.0 9.5

1.6

Auckland

18.1

17.5

—

14.7

14.2 18.2

9.1

7.6 8.7 18.4 11.3

8.0

Bahrain

4.8

2.8

14.7

—

5.4

2.4

0.5

4.4

6.4

7.0 6.0

5.1 3.4

7.4 12.1 8.5

Bangkok

9.2

7.9

9.6

5.4

—

3.0

4.9

9.0

1.7

2.3 1.2

9.5 2.2

2.2

Mumbai

6.9

5.2

12.3

2.4

3.0

—

1.9

6.6

4.3

4.7 3.6

7.2 1.0

5.1

Dubai

5.2

3.3

14.2

0.5

4.9

1.9

—

4.8

6.0

6.6 5.5

5.5 2.9

6.9 11.6 7.6

Frankfurt

0.4

1.8

18.2

4.4

9.0

6.6

4.8

—

9.2 11.2 9.9

Hong Kong

9.3

8.5

9.1

6.4

1.7

4.3

6.0

9.2

—

3.3 2.5

Jakarta

11.4

9.8

7.6

7.0

2.3

4.7

6.6 11.2

KualaLumpur

10.2

8.7

8.7

6.0

1.2

3.6

5.5

London

0.4

2.4

18.4

5.1

9.5

7.0

Chennai

7.9

6.2

11.3

3.4

2.2

Manila

10.4

9.6

8.0

7.4

Melbourne

16.5

14.9

2.6

Osaka

9.0

9.3

Paris

0.4

Perth

9.6 12.3

9.6 14.9 9.3

5.3 18.4

9.6 8.4

4.8

9.5

3.9

7.1 6.3 12.5 6.5 8.3

4.3

7.4 4.2

9.4

5.4

8.8

3.7 1.4

7.5 2.5 4.6

9.0

9.8 6.3

7.0 7.3.

6.2

5.6 3.9 10.1 5.0 6.7

6.5

5.2

9.0

4.3

6.8 5.8 12.0 6.6 7.9

4.8

0.7 7.6 10.3 16.3 9.2

0.5 13.8

1.0

8.6 10.3 16.5 9.4 9.4

0.3

9.6 3.8

1.1

7.4 2.5

0.6

9.3

2.2 2.6

7.4 0.8 2.9

9.3

3.3

— 1.2 11.7 3.6

2.8

5.2 5.8 11.6

3.0 10.9

5.5 0.9

5.3 3.7 5.8 11.1

9.9

2.5

1.2

2.5

6.4 4.6 10.4

4.2

9.7

4.6 0.3

6.6 3.2 5.3 10.0

5.5

0.7

9.6 11.7 10.6

— 8.2 10.8 16.9 9.5

0.4 14.5

1.4

8.9 10.9 17.0 9.8 9.6

0.8

1.0

2.9

7.6

3.8

3.6 2.6

8.2

—

4.8

8.8 6.1

8.0

7.2

5.9 2.9

9.1 4.7 6.8

7.6

2.2

5.1

6.9 10.3

1.1

2.8 2.5 10.8 4.8

—

6.3 2.7 10.8

4.9 10.4

2.5 2.4

6.3 1.0 3.0 10.4

12.1

7.4

9.8

11.6 16.3

7.4

5.2 6.4 16.9 8.8

6.3

— 7.8 16.8

2.7 16.0

8.3 6.0

4.0 7.5 8.2 16.3

9.0

8.5

4.2

6.3

7.6

9.2

2.5

5.8 4.6

2.7

7.8 —

8.0

9.7

0.8 4.9

7.8 1.7 0.4

9.4

2.1

18.6

4.8

9.4

7.0

5.2

0.5

9.6 11.6 10.4

0.4 8.0 10.8 16.8 9.6

— 14.3

1.1

0.0 10.7 17.0 9.8 9.7

0.5

14.1

12.3

5.3

9.5

5.4

7.3

9.0 13.8

6.0 3.04.2 14.5

6.3 4.9

8.0 14.3

— 13.3

5.0

3.9 3.3

Rome

1.3

1.1

18.4

3.9

8.8

6.2

4.3

1.0

9.3 10.9 9.7

1.4 7.2 10.4 16.0 9.7

1.1 13.3

—

9.0 10.0 16.0 9.6

Seoul

8.6

8.3

9.6

7.1

3.7

5.6

6.8

8.6

2.2

5.5 4.6

8.9 5.9

2.5

8.3 0.8

9.0

5.0 9.00

Singapore

10.5

9.0

8.4

6.3

1.4

3.9

5.8 10.3

2.6

0.9 0.3 10.9 2.9

2.4

6.0 4.9 10.7

Sydney

16.6

15.3

2.2

12.5

7.5 10.1

12.0 16.5

7.4

5.5 6.6 17.0 9.1

6.3

Taipei

13.7

9.0

8.9

6.5

2.5

5.0

6.6

9.4

0.8

3.7 3.2

9.8 4.7

Tokyo

9.3

9.5

8.8

8.3

4.6

6.7

7.9

9.4

2.9

5.8 5.3

9.6 6.8

Zurich

0.6

1.6

18.4

4.3

9.0

6.5

4.8

0.3

9.3 11.1 10.0

— 10.6 2.6

9.5 6.1

2.7

2.6 9.0 18.6

6.3

6.4 8.5 13.8 99

0.7

— 4.7

8.7 1.5 1.2

8.8

3.9 10.0

4.7

—

4.0 3.2 5.3 10.3

0.7 7.8 17.0

3.3 16.3

8.7 6.3

— 7.3 7.8 166

1.0

7.5 1.7

9.8

6.4

9.6

1.5 3.2

— — 2.1

9.6

3.0

8.2 0.4

9.7

8.5

9.9

1.2 5.3

— 2.1

—

9.6

0.5 13.8

0.7

8.8 10.8 16.6 9.5 9.16

—

0.8 7.6 10.4 16.3 9.4

WBSEBEA - 12

9.6

6.0

2.2 8.9 8.8 18.4

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AHMEDABAD

PUNE

JAIPUR

INDORE

DELHI

COCHIN

PONDICHERRY

230

PATNA

691

PANJIN

1253

NASIK

200

NAGPUR

3330 2891

1957 2278

M UNMBAI

3493 4304 2708

449

LUCKNOW

2998

1556

KOLKATA

2286

1819

KANPUR

3824

855

HYDERABAD

3305

CHENNAI

CHANDIGARH

AGRA

BHUBANESWAR

AGARTALA

AHMEDABAD

DISTANCE IN KILOMETERS

BANGALORE

ROAD DISTANCE OF MAJOR CITIES

2801 2281 1863 2252 3593 2696 3365 3507 1681 3661 3442 290 1242

369 1208 785 1005 1715 885 2119 1229

—

1514

1829

1135

1848 1832

886

1220

442

625 1168 2006 1133

ALLAHABAD

1207

1652

1102

892

1790 2216

643

1086

803

673

193 799

237 1444 618 1155 1419 402 1952 1465

AMRITSAR

1332

2453

2202

223

2603 3011

446

1899 1258

707

926 1888

945 1854 1431 1665 2237 1531 2765 1875

ASANSOL

1842

2187

523

1503

1857 2544 1262

1693 1394

1304

789 226

825 2040 1122 1746 2300 395 2024 1955

BANGALORE

1514

-

1430

2268

334 546 2019

BARODA

119

1408

1604

1181

1739 1763 1151

BHOPAL

571

1379

1175

990

BHUBANESWAR

1829

1430

-

1994

1225 1895 1745

1063 1335

CALICUT

1648

520

1923

2741

715 222 2494

910 1998

CHANDIGARH

1135

2268

1994

-

CHENNAI

1848

334

1225

2406

COCHIN

1832

546

1895

2814

669

- 2565

COIMBATORE

1669

333

1633

2669

426 195 2412

886

2019

1754

248

2157 2565

-

1453

806

1834 2246

319

1134

497

DELHI GWALIOR

1517 1925

2406 2814

741

556 1601

552 999

504 1165 1656 1818 675

2049 1855 1883 1900 1033 1034 1035

440 2071 303 839

1127

379

789 1230 1937 1311

433 774

457 1158 1582 1735 454

813

191

735

789 345

605 1143 1016 1679 810

585 1456

703

1775 1283 480 1266 1691 830 1516 1455 862 1387 1608 2523 2260 2346 2339 1171 1483 1193 510

661 1691

576 2476 566 984

248

1702 1053

748 1657 1234 1466 2028 1332 1568 1678

- 669 2157

704 1795

2187 2049 1678 2038 1367 1172 1366

909 2096 162 1173

112 1804

2457 2385 2347 2446 1351 1580 1390

798 2601 548 1169

912 1964

2369 2218 2057 2297 1192 1441 1241

800 2434 410 1005

263

481 1442

569 1408 985 1220 1782 1086 2319 1429

351

280 1232

359 1085 666

852

1700

1496

568

HUBLI

1101

391

1620

2101

638 774 1854

HYDERABAD

1220

566

1063

1702

704 1112 1453

IMPHAL

3067

3489

2100

2752

3298 4035 2503

INDORE

442

1601

1355

1052

1795 1804

806

999

-

405

689 1620

768

589 445

414 1115 1205 1963 523

JABALPUR

901

1335

1087

1046

1529 1885

800

733

589

845

543 1167

584 1143 257

943 1088 736 1697 1003

2187 2457

263

1483

JAIPUR

486 1060 -

999

2923 2744

891 1467 406 2000 1110

1060 1772 2032 1851

641 995

646

190 1998 653 437

1483 1253 1516 1334

739 468

754

765 1469 865 545

2533 2134 1620 1979 3316 2455 3218 3360 1534 3460 337

625

2049

1775

510

JAMSHEDPUR

1870

1842

439

1566

JULIANDUR

1285

2416

2413

154

KANPUR KOLHAPUR

1168 911

1855 484

1283 1622

661 1910

2049 2385 481 910 934 1664

1253 578

KOLKATA

2006

1883

480

1691

1678 2347 1442

1516 1620

LUCKNOW

1133

1900

1266

748

2038 2446

569

1334

768

598

79 963

- 1370 866 1182 1883 566 2200 1391

LUDHIANA

1220

2358

2088

105

2552 3027

310

1756 1115

570

790 1783

803 1770 1280 1528 1805 1395 2720 1726

MADURIA

1922

432

1687

2785

MEERUT

1092

2072

1822

381

MUMBAI

552

1033

1691

1657

NAGUR

999

1034

830

NASIK

504

1035

1516

PANJIM

1165

440

1455

PATNA

1656

2071

PONDICHERRY

1818

303

1387

2568

162 548 2319

675

839

1608

1678

1173 1169 1429

RANCHI

1781

2098

560

1480

1767 2455 1214

1434 1333

1243

SHILLONG

2698

3120

1739

2383

2929 3666 2134

2554 2309

2164 1699 1251 1610 2947 2086 2800 2925 1019 3051 2968

SHIMLA

1254

2387

2113

119

2525 2933

1821 1171

SURAT

273

1284

1579

1325

PUNE

405

-

917 1472

298 1176 1015 1248 1488 1115 2300 1300

1637 2306 1317

1578 1477

1347

867 308

838 1958 1097 1788 2229 473 1799 979

2617 3082

1821 1171

891

855 1869

868 1778 1354 1591 2146 1460 2785 791

375

480 326 2539 2266 2741

689 870

995 2091

517 - 1010 79 1278 777 1103 1813 596 2217 1312 1518 1779 2045 1858 426 1050 456 2091 2047 907 247 1472 1010

-

963 2081 1220 1849

2496 2345 2110 2424 1458 1568 1467

1470

815

1367 1351 1408

739

589

1176 1278 2081 1370

1234

1172 1580

985

468

445

1015

1466

1366 1390 1220

754

414

1248 1103 1849 1182

197 700

-

701 1679 1363 209

2028

909 798 1782

765 1115

2496 1613 974 1885

584 1247

701

- 1804 739 501

862133220962601 1086 1469

1205 1115

1695 1593 1182 713 218 1950

596

537 1497

872 2561 333 1238

66

368

327

974 621 1840 2102

777 1220

453 1468 994 1242 1805 934 2434 1440

866

621 566 1856

- 861 861

-

197

584 1856 1336 164

700 1247 993 1334 882

993 1679 1804

- 2264 2738

865 1963

2349 2217 1840 2200 1336 1334 1363

739 2264

545

1300 1314 2102 1391

501 1758 1142

983

623

607

846 1610

209

- 1142 -

912 1816 958 1615 1630 30219*35 1975

867 1776 1353 1567 2130 1434 2687 1797

932 1296 1912 1375

301 747

262

913 1742 1789 432

2782 2611 2376 2690 1376 1834 1742

792 2827 622 1533

TRIVANDRUM

2197

690

1953

3051

VARANASI

1329

1763

980

1014

VIJAYAWADA

1491

638

792

1973

433 1102 1724

271 1255

1754 1519 1245 16905 1010

VISAKHAPATNAM

1857

1004

426

2110

799 1468 1861

637 1433

1891 1687 879 1742 1376 876 1596 1206 1334 961 1182

1901 2309

765

1261 2150

629

726 414

164 882

1197

925

795

WBSEBEA - 13

315 677

286 1590 729 1399 1524 280 1063 1116 39 1428

876 1664 595 816

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GREETINGS National a) Kind rememberence and all good wishes for the independence day. b) Sincere greetings for the republic day. c) Long live the republic Election a) Hearty congratulations on success in Election b) Best wishes for your success in the Election Festival Heartiest Diwali Greeting Id Mubarak Heartiest Bijoya Greetings A Merry Christmas to you My Heartiest Holi Greetings to you Heartiest Pangal Greetings Heartiest Onam Greeting Heartiest Ugadi Greeting Wish you a happy Bihu A Happy Easter Heartiest Greetings on Buddha Jayanti Heartiest Guru Ravidas Purnima Greetings Special Occations A Happy New Years to you Many Happy Returns of the day Greeting on the duation of Paryushan

Day of Universal Forgiveness. Hearty Congratulation on the new Arival. Heartiest Congratulation on Griha Pravesh Wedding Best Wishes for a long & happy Married life Many Heaven's choicest Blessing be showered on the young couple. Wish you both a happy & prosperous Wedded life Convey our Blessings to the Newly Married couple. Best Wishes on your Wedding anniversary. General Congrtualation of the Distinction conferned to you. Hearly congratulations on your success in the Examiantion Best Wishes for a safe & pleasant journey Many Thanks for your Good wishes which I/ We reciprocate Most Hearitily Congratulations Loving Greetings. Wishing the function Every Success. Many thanks for your kind massage to greeting. Best Wishes for your success in the Examination.

WBSEBEA - 14

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NATIONAL INFORMATION States

Main Language

Capital

Best Season

Area in 100 sp.km

Andhra Pradesh

Telugu

Hyderabad

Nov. to Mar

277

Assam

Assemise

Dispur

Oct to May

79

Arunachal Pradesh

Tribal

Itanagar

Oct to May

89

Bihar

Hindi

Patna

Oct to Mar

174

Delhi

Hindi

New Delhi

Oct to Mar

1.5

Goa

Konkani, Marathi

Panaji

Oct. to May

3.8

Gujrat

Gujrati

Gandhinagar

Oct to Mar

196

Haryana

Hindi

Chandigarh

Oct to Mar

44

Himachal Pradesh

Hindi, Pahari

Shimla

April to Oct

56

Jammu & Kashmir

Kashmiri

Jammu (Winter)

Dec. to Mar

22

Srinagar (Summer)

Apr. to Oct.

Karnataka

Kanada

Bangalore

Nov. to Apr

192

Kerala

Malayalam

Trivandrum

Oct to Apr.

39

Madhya Pradesh

Hindi

Bhopal

Sept to March

443

Maharashtra

Marathi

Mumbai

Nov to May

308

Manipur

Manipuri

Imphal

Sep to Apr.

22

Meghalaya

Tribal

Shilong

Nov to Mar

22

Mizoram

Mizo

Aizwal

Oct to May

21

Nagaland

Angami

Kohima

Oct to Mar

17

Orissa

Oriya

Bhubaneswar

Oct. to Mar

156

Punjab

Punjabi

Chandigarh

Oct to Mar

50

Rajasthan

Hindi

Jaipur

Oct to Mar

7

Tamilnadu

Tamil

Chennai

Nov. to Mar

130

Tripura

Tripuri

Agartala

Sept. to Mar

10

Uttar Pradesh

Hindi

Lucknow

Oct to Mar

294

Wet Bengal

Bengali

Calcutta

Oct to Mar

88

WBSEBEA - 15

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LIST OF FESTIVAL - 2006 NAME OF FESTIVALS

DAYS

DATES

NEW YEAR'S DAY

SUNDAY

1ST JANUARY

ID-UD-ZOHA

WEDNESDAY

11TH JANUARY

MAKAR SANKRANTI / PONGAL

SATERDEY

14TH JANUARY

NETAJI BIRTHDAY

MONDAY

23RD JANUARY

REPUBLIC DAY

THURSDAY

26TH JANUARY

SARASWATI PUJA

FRIDAY

3RD FEBRUARY

SREE PANCHAMI

FRIDAY

3RDFEBRUARY

MUHARRAM

THURSDAY

9TH FEBRUARY

SHIV RATRI

SUNDAY

26TH FEBRUARY

DOL-JATRA/HOLI

TUESDAY

14TH MARCH

GOOD FRIDAY

FRIDAY

14TH MARCH

YEARLY BANK CLOSING

SATURDAY

1ST APRIL

RAMNAVAMI

FRIDAY

7TH APRIL

MAHAVIR JAYANTI

TUESDAY

11TH APRIL

BENGALI NEW YEAR

SATURDAY

15TH APRIL

MAY DAY

MONDAY

1ST MAY

RABINDRAJAYANTI

TUESDAY

9TH MAY

FATEHA-DOAZ DAHAM

TUESDAY

11TH APRIL

BUDDHA PURNIMA

SATURDAY

13TH MAY

JAMAI SASTHI

MONDAY

13TH JUNE

RATHJATRA

TUESDAY

27TH JUNE

GURU PURNIMA

TUESDAY

11THJULY

BIRTHDAY OF BHANU BHAKT

TRURS DAY

13 TH JULY

RAKHI PURNIMA

WEDNESDAY

9TH AUGUST

INDEPENDENCE DAY

TUESDAY

15TH AUGUST

JANMASTAMI

WEDNESDAY

16TH AUGUST

SABEMIRAJ

TUESDAY

22THAUG

SABEBARAT

SATURDAY

9THSEPTEMBER

MAHALAYA

FRIDAY

22ND SEPTEMBER

HALF YEARLY BANK CLOSING

THURS DAY

28TH SEPTEMBER

DURGA PUJA

MONDAY-WEDNESDAY

29TH SEP-2ND OCT

EKADASI OF DURGA PUJA

TUES DAY

3RD OCTOBER

LAXMI PUJA

FRIDAY

6TH OCTOBER

DIPAWALI/KALIPUJA

SATURDAY

21STOCTOBER

ID-UL-FITRE

WEDNESDAY

25TH OCTOBER

JAGADDHATRI PUJA

THURSDAY

10TH NOVEMBER

BHATRIDWITIYA

TUESDAY

24TH NOVEMBER

GURUNANAK BIRTH DAY

SUNDAY

5TH NOVEMBER

X-MAX DAY

MONDAY

25TH DEC.

(FOR DARJEELING DIST)

WBSEBEA - 16

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CONVERSION FACTORS Quantity

Imperial Unit

Metric Unit

Imperial to Metric Unit

Metric to Impertal Unit

Length

Inch (in Foot (ft) Yard (yd) Furlong (fur) Mile International nautical mile (for Navigation)

Milimeter (mm) or Centimeter (cm) Centimeter or meter (m) Meter or Kilometer (km) Kilometer (km) 1 mole = 1862 m

1 in = 25.4 mm 1 ft = 30.5 cm 1 yd = 0.194 m 1 fur = 301 m 1 mole = 1.61 km 1 km = 3.28 ft.

1 cm = 0.39 in 1 m = 3.28 ft 1 m = 1.09 yd 1 km = 4.97 fur 1 km = 0.621 mile

Mass

Ounce (oz) Pound (ib) Stone Ton

Gram (g) Gram or Kilogram (kg) Kilogram (kg) Tonne (t)

1 oz = 28.3g 1 lb = 254 g 1 s tone = 6.15 kg 1 ton = 1.02 t

1 g = 0.0358 oz 1 kg = 2.20 lb 1 kg = 0.157 stone 1 t = 0.984 ton

Area

Square inch (in2) Square foot (ft2)

1 in2 = 6.45 cm2 1 ft2 = 929 cm2

1 cm2 = 0.155 in2

Square yard (yd2) Perch (p) Rood (rd) Acre (ac) Square mile

Square centimeter (cm2) Square centimeter (cm2) or Square meter (m2) Square meter (k2) Square meter (m2) Hectare (ha) Hectare (ha) Square kilometer (km2)

1 yd2 = 0.836 m2 1 p =25.3 m2 1 rd = 0.101 ha 1 ac = 0.405 ha 1 sq.mile = 2.95 km2

1m2 = 108 yd2 1 m2=0.395 p 1 h a = 9.88 rd 1 ha = 2.47 ac 1 Km2=0.386 sq.mile

Volume

Cubic inch (in2) Cubic foot (ft3) Cubic yard (yd3) Bushel (bus)

Cubic centimeter (cm2) Cubic meter (m3) Cubic meter (m3) Cubic meter (m3)

1 in2 = 16.4 cm3 1 ft3 = 0.0283 m3 1 yd3 = 0.765 m3 1 bus = 40.0364 m3

1 cm3=0.610 in3 1 m3=35.3 ft.2 1 m3=1.31 yd3 1 m3=27.5 bus

Volume (fluid)

Fluid ounce (fl oz) Pint (pt) Gallon (gal) Acre foot

Mililiter (ml) Mililiter (ml) or liter (1) Liter (1) or cubic leter (m3) cubic liter (m3) or magaliter (ML)

1 ft oz = 28.4 ml 1 pt = 568 ml 1 gal = 4.55 liter 1 acre foot = 1230 m3 = 1.23 ML

1 ml = 0.0352 ft. oz 1 ml = 1.76 pt 1 m3 = 220 gel 1 ml=0811 acre foot

Force

Pound-force (1bf) Ton-force (tonf)

Newton (N) Kilonewton (kN)

1 lbf = 4.45 N 1 tonf = 9.95 Kn

1 N = 0.225 1bl 1 kN = 0.100 tonf

Pressure

Pound per square inch (psi) Atmosphere (atm)

Kilopascal (k Pa)

1 psi = 6.89 kP2

1 kPa = 0.145 psi

Kilopascal (kPa) or megapascal (MPa) Megapascal (MPa)

1 atm = 9;.96 101 kPa 1 ton/in2=15.4 MPa

1 mPa = 09.87 atm 1 MPa=0.647 ton/in2

Milibar (mb)

1 in Hg=33.9 mb

1mb=0.0295 in Hg

Ton per square inch (ton/in2) Inch per mercury (in Hg( (for navigaton) Velocity

Mile per hour (mph) Knot (kn) (for navigation)

Kilometer per hour (km/h)

1 mph=1.61 km/h =1 kn=1.58 km/h

1 km/h=0.621 mph

Temperature Density

Degree Fahrenheit (F) Pound per cubic inch (ib/in2)

Degree C elcius (oC) Gram per cubic cm (g/cm2) =tonne per cubic meter (t/m3) tonne per cubic meter (t/m3)

oC=5/9 (F-32) 1 1b/in2=2.7 g/cm3

oF=9/5 (C+32) 1 g/cm3=0.036 inch

1 1b/in3=27.7 t/m3 1 ton/yd3=1.33 t/m3

1 t/m=0.0316 1b/in3 1 t/m=0.752 ton/yd2

British thermal unit (Btu) Therm (for electrical energy)

Kilojoule (KJ)

1 Btu = 1.06 KJ

1 KJ=0.948 Btu

Megajoule (MJ) Kilowatt hour (kWh)

1 therm=106 MJ =kWh=3.60 MJ

1 MJ=9.48x103 therm

Horsepower (hp)

Kilowatt (kW) Second (s) hour (hr)

1 hp=0.746 kW 1 min=60s 1 h = 1600s

1 kW=1.34 hp

Ton per cubic yard Energy

Power Time

Minute (min)

WBSEBEA - 17

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GRAPHICAL SYMBOLS for use in connection with interior electrical installation Description

Symbol

19. Bulk-head fitting

B.1. CONTROL GEAR AND DISTRIBUTION FUSEBOARDS 1. 2. 3.

Description

20. Power factor capacitor (when installed remote from the lamp unit

Main fuse-board without switches, lighting ... ... ...

21. Lighting outlet connection to an emergency system

Main fuse-board with swi tches, lighting ... ... ....

22. Choke (when installed remote from the lamp unit)

Main fuse-board without switches, power ... ... ...

B.3. SWITCH OUTLETS

Main fuse-board with switches, power

23. One-way switch

5.

Distribution fuse - board without switches, lighting ...

25. Intermediate switch

6.

Distribution fuse-board with swticehs, lighting ...

7.

Distribution fuse - board without switches power ...

4.

24. Two-way switch

26. Pendant switch 27. Pull Switch B.4. SOCKET OUTLETS 28. Socket-outlet, 3 pin 5 A

8.

Distribution fuse-board with sitches power ...

29. Socket outlet and switch combined. 3 pin 5 A

9.

Main switches, lighting .. ..

30. Socket - outlet, 2pin 15A.

10. Main s witchs, power ... ...

31. Socket-outlet, 3 pin 15A

11. Meter ... ... ...

32. Socket-outlet and switch combined, 2 pin 15A.

B.2. CEILING OUTLETS

33. Socket outlet and switch combined 3 pin 15 A.

12. Single light pendams .. ... 13. Counter weight pendant .. ...

CW

14. Rod pendant

R

15. Chain pendant

C

16. Light Bracket

B.5. FIXED HEATING OUTLETS 34. Convention heater 35. Electric unit heater 36. Immersion heater

17. Batten lampholder

BN

37. Thermostat

18 . Water - tight light fitting

WT

38. Immersion heater with incorporated thermostat

WBSEBEA - 18

Symbol

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Description 56. Loudspeaker outlet

39. Self-conditioned electric water heater H

40. Humidistat B.6. BELLS AND BUZZERS

B.10.RADIO RECEPTION OUTLETS 57. Receiver outlet

41. Bell push

58. Aerial

42. Bell 43. Buzzer

B.11. FIXED APPARATUS OUTLETS

44. Indicator (at 'N', Insert number of ways)

59. Ceiling fan

B.7. CLOCKS 46. Synchronous clock outlet 47. Impulse clock outlet 48. Master clock

VV

60. Braket fan

ä ä

45. *Relay

Symbol

61. Exhaust fan N

v v v

62. Fan regulator 63. Cooker control unit B.12. EARTHING 64. Earth point

Û

B.8. FIRE ALARMS

s

Description

B.13. OTHER SYMBOLS

50. Automatic contact

66. Pilot or corridor lamp

51. Bell connected to fire alarm

52. Fire alarm indicator (at 'N' Insert number of ways)

N

54. Control board

55. Microphone outlet

*

67. Indicator (buzzer may be added if required)

N

68. Relay

B.9. PUBLIC ADDRESS SYSTEM 53. Amplifier ..

Û

65. Surge diverter

49. Fire alarm push

A .....

69. Reset position

70. Horn or hooter 71. Siren

X

This general symbol is applicable to any system by the addition of an identifying symbol (appropriate to particular system) in the upper half, for example, bell system relay. Where items of operations are combined, the symbols may be combined, for example, idicator and bell At 'N' insert the number of ways.

WBSEBEA - 19

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PRELIMINARIES OF TOWER LOADING CONCEPT 1.

(a)

(b)

(c)

(A)

(B) (C)

(A) (i) (ii)

(B)

Classification of Loads : (a) Climatic Loads : Related to Reliability requirements (b) Failure containment Loads - Related to security requirements (c) Construction & maintenance Loads - Related to safety requirements. Climatic Loads : Due to action of wind on conductor / G.W., insulator and do not act continuously. This load shall be determined under either of the following climatic conditions which every is more stringent. (i) 100% design wind pressure at everyday temperature. (ii) 36% design wind pressure at minimum temperature. Failure containment Loads : These loads comprises of (i) Anti cascading loads (ii) Torsional and longitudinal loads. (a) Cascade failure may be caused by failure of items such as insulators, hardware, joints, failures of major components due to defective materials. (b) Caused due to breakage of conductors and groundwires. Construction & maintenance Loads : During construction and maintenance of Transmission Lines. Computation of loads : (A) Transverse load, (B) Longitudinal Load (C) Vertical Load Transverse Load - Reliability requirements - Normal condition (i) Wind load on tower structures, conductors, ground wires and insulator strings. (ii) Component of mechanical tension of conductor and ground wire due to line deviation. Transverse load : FWt - FWe - FWt - Fwd whereFwt - Wind on tower body Fwe - Wind on Conductor GW Fwi - Wind on insulator Fwd - Mechanical tension Longitudinal Load - No load for suspension or tension tower but only for D.E. Tower Vertrical Load - Due to wt. of conductor / groundwire, insulator and asscesories and S/W of tower str on weight span. Security requirements : Broken wire condition. Transverse Loads : For tangent type tower - 75% of W.L. on insulator, conductor / groundwire and tower body, for tension tower Full wind on insulator, conductor / groundwire and tower body. Component of mechanical tension due to line deviation. 50% of tension At 32o & 75% Full wind for conductor Suspension 100% of tension At 32o & 70% Full wind for Groundwireq Tower Tension AT 32o Full wind Longitudinal Load : 50% of tension at 32o, 75% Full Wind- for Suspension Tower 100% of tension at 32o Full Wind- for Tension Tower For D.E. Tower - nil

WBSEBEA - 20

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. (C) Vertical Load - S/W of conductor, G.W. Insulator S/W of Tower on span 60% of wt. span. Safety requirement : (A) Transverse Load (i) W.L. - Nil (ii) Due to mechanical tension at 32o, Nil wind for line deviation. (B) Longitudinal Load :For Suspension TowerFor sub-conductor & G.?W. as 10,000 N & 5000 N respectively For Tension Tower2 x T (T-50% of tension at 32o Nill Wind) Under stringing 1.5 x T (T-50% of tension at 32o Nil Wind)Stringing completed (C) Vertical Loads (S/W conductor, G.W., insulator, and S/W of Tower body) x 2 S/W - self weight. For Anticascading check (A) Transverse Load - At no wind condition (B) Longitudinal Load - At 32 deg, Nil wind tension, Zero degree line deviation. (C) Vertical Load - Sum of wt. at conductor / G.W. as per wt span of intact conductor / G.W., wt of insulator string and accessories.

↓ →

→ ↓

(N.C.)

↓

→

→

→ ↓

→

↓

↓

↓ → ↓ → ↓→ ↓ →

(B.W.C)

↓→

→ → → →

→ ↓ → ↓

→

↓

→

→

→

↓

↓ → ↓→

↓ →

WBSEBEA - 21

→ → → →

↓

↓

→ → →

↓ → ↓→

→

→

↓→

→

↓

↓

↓

↓ ↓ ↓ → ↓ →

→ → → →

→ ↓ → ↓

↓

→

D.E. (N.C.)

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EFFECT OF WIND Basic wind speed VbReference wind speed VR VR = Vb/Ko, Ko = Factor to convert 3 sec. peak gust into averaging period of 10 min - 1.375 Designed wind = Vd = VR x K1 x K2 speed

K 1 Risk coeff K 2 Teerain Roughness coeff.

Designed wind = Pressure Pd = 0.6 Vd2 On Tower body Fwt = Pd x Cdt X Ae x GT

Pd Ac = GT =

Design wind pressure in N/m2 Cdt = Drag coeff Net suface area Gust response factor, related to ground roughness & ht above ground level.

Wind on conductor & G.w. Fwc = Pd x Cdc x L x d x Gc Pd = design wind pressure, Cde - drag coeff - for conductor - 1 for GW 1./2

→

L = wind Spain in meter d = diameter of cable in meter Gc = yest response fatter

→

→

Wind load on Insulator st.. Fri - Cd x Pd x Ai x Gi

→

→

→

Edi = drag coeff taken as 1.2

→

Pd = design wind pressure Gi = Gust response factor

→

Di = 50% of profelted area of insulator

WBSEBEA - 22

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. SAG TENSION CALCULATION : n

Sag tension parabolic eq f2 [f- (K-E alpha t) ] = (12 delta2 E q2) / 24 f = Working tensile stress of conductor on kg/cm2 k = Computed from initial temperature and wind pressure conditions assumed. E = Final Modules of Elasticity in kg/cm2 alfa = Coef of linear expansion of conductor per dg C. t = Change of t emperature = Final - initial in deg C. 1 = Span length in meter dealt = Wt of conductor / m / Cm2 = W/A kg/m/cm2 where A = cross sectional area of conductor in cm2 q = loading factor = SQRT ((W2 + P2) / W2)) Where W = Wt at conductor in kg/m length of conductor P = Wind load in kg/m length of conductor If suffix "1" corresponds to temp. condition at Every day temperature with maximum wind "2" to everyday temperature with still wind and "3" to maximum temperature in still wind condition, the above sag - tension formula are written as follows : (a) Everyday temp. 32 deg c in still wind (assumed as starting initial condition Suffix - 1) f22 [f2-(K-E alpha t)] = (12 delta2 E q22) / 24 (1) Assume (12 delta2 E) / 24 = Z and initial temp t2 = 32 dg C t = 0, E alpha t = 0, q2 = 1 Ultimate strength of conductor f2 = ------------------------------------------------------FOS (4) x cross actional area on cm2 (A) Substiutng the above values in the equation and solving K = f2 - Z/f22 (B) Every day temperature ith full wind (suffix - 1) f 2 [f1- {k-E alfa (t1 - t2)} = Zq12 - (2) 1 Value of K computed from (a) is substituted in (2) and the cubic equation is solved for f2- the maximum tensile stress of the conductor. If T1 is the maximum tension at the Everyday temperature with full wind T1 = f1A F.O.S. = T (Ultimate Strength) / T1 FOS is equal to o r > 70% i.e. 1.454. value at k computed from (a) and q3 = 1, substitute in (3) and solved for f3 - find f3 at maximum temperature & still wind. q3 delta 12 Maximum sag = --------------- m (inclined) 8f2 A sample sag - tension chart is given in next page.

WBSEBEA - 23

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Wind Acting Perpendicular to the line Conductor Groundwire

......................

Strands In Aluminium Strand in Steel Diameter .. Sectional Area Unit Weight Modulus of Elasticity Coffe. of Linear Exrn. Ultimate Strength Wind Pressure Details Full Wind Pressure ... Exposure Factor ..

NCCM NOCM Cm CM2 KG/M KG/CM2 PER DG KG

Panther ACSR 30/0.30 7/0.30 2.100 2.617 0.976 0.78700E + 06 0.17800E-04 9127.

KG/.M2 1.000

166.00 1.000

GSW

0.945 0.546 0.428 0.19330E=07 0.11500E=04 5710. 207.00

CONDUCTOR SR WIND No FACT

WIND Press

Temp [DDG-C)

Sag (M)

Tension (KG)

FOS AVAL

Fos REQD

1 2 3

1.0000 0.0000 0.3600

16.000 NIL 59.760

32.0 32.0 4.0

5.125

4840.3 2142.4 3328.3

1.886 4.260 2.742

1.428 4.000 1.429

4 5

0.0000 0.0000

NIL NIL

4.0 75.0

4.175 6.640*

2629.8 1653.6

3.471 5.519

1.429 1.429

GW Made Parallel AP Condition 4 (Parallel Factor for GW = 0.9000) GROUND - WIRE

SR WIND No FACT

WIND Pres

Temp [DDG-C)

Sag (M)

Tension (KG)

FOS AVAL

Fos REQD

1 2 3 4 5

207.000 NIL 74.520 NIL NIL

32.0 32.0 4.0 4.0 53.0

2691.1 4.379

2.122 1099.6 1733.8 1281.4 988.0

1.426 5.192 3.293 4.456 5.780

4.000 1.428 1.428 1.428

1.0000 0.0000 0.3600 0.0000 0.0000

3.758* 4.874

NOTE : * Indicates starting condition.

WBSEBEA - 24

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. 11.7.1 METHOD OF ERECTION : There are four main methods of erection of steel transmission towers which a re described below : (i) Build-up method or Pecemeal method. (ii) Section method. (iii) Ground assembly method. (iv) Helicopter method. 11.7.1.1. Build Up Method This method is most commonly used in this country for the erection of 6.6 kV, 132 kV, 220 kV and 400 kV transmission line towers due to the following advantages : (i) Tower materials can be supplied to site in knowcked down condition which facilitates easier and cheaper transportation. (ii) It does not require any heavy machinery such as cranes etc. (iii) Tower erection activity can be done in any kind of terrain and mostly throughout the year. (iv) Availability of workmen at cheap rates. This method consists of erecting the towers, member by member. The tower members are kept on ground serially according to erection sequence to avoid search or time loss. The erection progresses from the bottom upwards. The four main corner leg members of the first section of the tower are first erected and guued off. Sometimes more than one contiguous leg sections of each corner leg are bolted together at the ground and erected. The cross bracs of the first section which are already assembled on the ground are raised one by one as a unit and bolted to the already erected corner leg angles. First section of the lower thus built and horizontal struts (belt members) if any, are bolted in position. For assembling the second section of the tower, two gin poles are placed one each on the top of diagonally opposite corner legs. These two poles are used, for raising parts of second section. The leg members and braces of this section are then hoisted and assembled. The gin poles are then shifted to the corner leg members on the top of second section to raise the parts of third section of the lower in position for assembly. Gin poles are thus moved up as the tower grows. This process is continued till the complete tower is erected. Cross-arm members are assembled on the ground and raised up and fixed to the main body of the tower. For heavir towers, a small boom is rigged on one of the tower legs for hoisting purposes. The members / sections are hoisted either manually or by winch machines operated from the ground. For smaller base towers / vertical configuration towers one gin pole is used instead of two gin poles. In order to maintain speed and efficiency, a small assembly party goes ahead of the main erection gang and its purpose is to sort out the tower membrs, keeping the members in correct position on the ground and assembling the panels on the ground which can be erected as a complete unit. Sketches indicating different steps or erection by build up method are shown in Annexure-'L'. 11.7.1.2. SECTION METHOD : In the section method, major sections of the tower are assembled on the ground and the same are erected as units. Either a mobile crane or a gin pole is used. The gin pole used is approximately 10 m long and is held in place by means of guys by the side of the tower to be erected. The two opposite sides of the tower section of the tower are assembled on the ground. Each assembled side is then lifted clear of the ground with the gin or derrick and is lowered into position on bolts to stubs or anchor bolts. One side is h held in place with props while the other side is being erected. The two opposite sides are then laced together with cross members and diagonals; and the assembled section is lined up, made square to the line. After completing the first section, gin pole is set on the top of the first section. The gin rests on a strut of the tower immediately below the leg joint. The gin pole then has to be properly guyed into position.

WBSEBEA - 25

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. The first face of the second section is raised. To raise the second face of this section it is necessary to slide the foot of the gin on the strut of the opposite face of the tower. After the two opposite faces are raised, the lacing on the other two sides is bolted up. The last lift raises the top of the towers. After the tower top is placed and all side lacings have been bolted up all the guyes are thrown off except one which is used to lower the gin pole. Sometimes whole one face of the tower is assembled on the ground, hoisted and supported in position. The opposite face is similarly assembled and hoisted and then the brancing angles connecting these two faces are fitted. 11.7.1.3. GROUND ASSEMBLY METHOD This method consists of assembling the tower on ground, and erecting it as a complete unit. The complete tower is assembled in a horizontal position on even ground. The tower is assembled along the direction of the line to allow the cross arms to be fitted. One slopping ground, however, elaborate packin of the low side is essential before assembly commences. After the assembly is complete the tower is picked up from the ground with the help of a crane and carried to its location, and set on its foundation. For this method of erection, a level piece of ground close to footing is chosen from the tower assembly. This method is not useful when the towers are large and heavy and the foundations are located in arable land where building and erecting complete towers would cause damage to large areas or in hilly terrain where the assembly of complete tower on sloping ground may not be possible and it may be difficult to get crane into position to raise the complete tower. In India, this method is not generally adopted because of prohibitive cost of mobile crane, and nonavailability of good approach roads to tower locations. 11.7.1.4. HELICOPTER METHOD : In the helicopter method, the transmission tower is erected in section. For example bottom section is first lifted on to the stubs and then the upper section is lifted and bolted to the first section and the process is repeated till the complete tower is erected. Sometimes a completely assembled toer is raised with the help of helicopter. Helicopters are also used for lifting completely assembled towers with guys from the marshalling yards where these are fabricated and then transported one by one to line locations. Helicopter hovers over the line location while the tower is securely guyued. The ground crew men connect and tighten the tower guys. As soon as the guy wires are adequately tensioned the helicopter disengages and files to the marshalling yard. This method is adopted where approach is v very difficult or to speed up the construction of the transmission line. 11.7.2. TIGHTENING OF NUTS AND PUNCHING OF THREADS AND TACK WELDING OF NUTS : All nuts shall be tightened properly using correct sized spanners. Before tightening it is ensured that filter washers and plates are placed in relevant gaps between members, bolt of proper size and length are inserted and one spring washer is inserted under e each nut. In case of step bolts, spring washer shall be placed under the outer nut. The tightening shall be carried on progressively from the top downwards, care being taken that all bolts at every level are tightened simultaneously. It may be better to employ four persons, each covering one leg and the face to his right. The threads of bolts shall be projected outside the nuts by one to two threads and shall be punched at three positions on the top inner periphery of the nut and bolt to ensure that the nuts are not loosened in course of time. If during tightening a nut is found to be slipping or running over the bolt threads, the bolt together with the nut shall be changed outright. 11.7.3. PAINTING OF JOINTS : For galvanized towers is coastal or highly polluted areas, the joints shall be painted with zinc paint on all contact surfaces during the course of erection. 11.7.4. CHECKING THE VERTICALITY OF ERECTED TOWERS : The finally erected tower shall be truly vertical after erection and no straining is permitted to bring it in alignment. Tolerance limit for vertical shall be one in 360 of the tower height.

WBSEBEA - 26

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CONCEPT OF TRANSMISSION TOWER FOUNDATION Foundation of any structure plays an important role in safety and satisfactory performance of the structure as it transsmits the loads from structure to earth. Without having a sound and safe foundation, structure cannot performs the functions for which it has been designed. The foundations in various types of soils have to be designed to suit the soil conditions of particular type. In addition to foundations of normal towers, there are situations where considering techno-economical aspect for special towers required or river crossing which may be located either on the bank of the river or in the mind stream or both, pile foundation may be provided. Type of loads on foundation : The foundation of towers are normally subjected to three types of forces. These are : (a) the compression or downward thrust (b) the tension or uplift (c) the lateral forces of side thrusts in both transverse and longitudinal directions. The magnitudes or limit loads for foundations should be taken 10% higher than these for the corresponding towers. The base slab of the foundation shall be designed for additional moments developing due to eccentricity of the loads. The additional weight of concrete in the footing below ground level over the earth weight and the full weight of concrete above ground level in the footing and embeded steel part also be taken into account; adding to the downthrust. Soil parameters For designing the foundations, following parameters are required. (a) Limit bearing capacity of soil. (b) Density of soil (c) Angle of earth frustum The above values are available from soil test report. 7.4. STABILITY ANALYSIS : 7.4.1. In addition to the strength design, stability analysis of the foundation shall be done to check the possibility of failure by over turning, uprooting of stubs, sliding and tilting of foundation etc. The following primary type of noil resistance shall be assumed to act in resisting the loads imposed on the footing in earth. 7.4.2 Resistance against uplift. The uplift loads shall be assumed to be resisted by the weight of earth in an inverted frustum of a pyramid of earth whose sides make an angle equal to the angle of reporc of the earth with the vertical in average soil. The volume of earth computation shall be as per e nclosed drawing (Fig.3) The weight of concrete embdded in earth and that above the ground level shall also be considered for resisting the uplift. In case where the frustum of earth pyramid of two adjoining legs overlaps each other, the earth frustum shall be assumed truncated by a vertical plane passing through the centre line of the tower base. Over load factor (OLF) of 10% (Ten percent) shall be considered over the design load i.e. OLF=1.10 for suspension tower and 1.15 for angle ower including dead end and anchor tower. However, for special tower OLF shall be 1.20. 7.4.3. Resistance against down thrust : The following load combinations shall be resisted by the bearing strength of the soil : (1) The down thurst loads combined with a dditional weight of concrete above earth are assumed to be acting on the total area of the bottom of the footing. (2) The moment due to side thurst forces at the bottom of the footing. The structrual design of the base slab shall be developped for the above load combination. In case of toe pressure calculation due to above load combination allowable bearing pressure to be increased

WBSEBEA - 27

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. by 25%. 7.4.4. Resistance against side thrust : The chimner shall be designed as per limit state method for the combined action of axial forces, tension and compression and the associated maximum bending moment. In these calculations, the tensile strength of concrete shall be ignored. 7.4.5. Resistance against uprooting of stub. : OLF of 10% (Ten percent) shall be considered i.e. OLF = 1.10 for normal suspension towers and 1.15 for angle tower including Dead end / anchor tower. For special towers OLF shall be 1.20. 7.4.6. The foundation and chimney shall be checked against axial tension combined with bending also. β

β

α

α

HU

HL

B

HLtenα HUtanβ

B HUtanβ H'Ltanα

Upper Portion A1 = B2 + 4 x B HL Tan a + A (HL tanA)2 A2 = B2 + 4 x B x (HL tan a + HU tan B) + A (HL tan a + HU tan B)2 VU = HU/3 [A1 + A2 + √A1 x A2] Lower Portion B2 HL + 2B HL2 tana + A / 3 HL3 - tan2

FORMULA FOR CONICAL PYRAMID FRUSTUM OF EARTH FIG.3

WBSEBEA - 28

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Annexure - I

GUIDELINES FOR CLASSIFICATION OF FOUNDATIONS IN DIFFERENT SOILS Sl. Name of soil encountered

Type of foundation to be adopted

1.

In good sil (silty sand mixed with clay)

Normal Dry

2.

Where top layer of Black Cotton soil extends upto 50% of the depth with good soil there after.

Partial Black Cotton

3.

Where top layer of black cotton soil exceeds 50% and extends upto full depth or is followed by good soil.

Black Cotton

4.

Where top layer is good soil upto 50% of the depth but the lower layer is a black cotton soil

Black Cotton

5.

Where subsoil water is met at 1.5 ml or more below the ground level in good soil

Wet

6.

Good soil locations which are in surface water for long period with water penetration not exceeding 1.0 m below ground level (e.g. paddy fields).

Wet

7.

In good soil where subsoil water is encountered between 0.75m and 1.5m depth from ground level.

Partially submerged

8.

In good soil where subsoil water is encountered within 0.75 m depth from ground level

Fully Submerged

9.

Where top l ayer of normal dry soil extends upto 85% of the d epth followed by fissured rock without presence of water.

Dry Fissured Rock

10. Where top layer is lissured rock followed by good soil/sandy soil with/without presence of water

Special foundation

11. Where normal soil/tissured rock extends upto 85% of the depth followed by hard rock

Dry fissured Rock with under cut in Fisured Rock combined with anchor bar for hard rock ddsign

12. Where fissure rock os encountered with subsoil water within 0.75m or below 0.75m from G.L. (Top layer may be either a good soil or black cotton soil)

Submerged Fissured Rock

13. Where Hard Rock is cncountered at 1.5 m or less below ground level.

Hard Rock

14. Where Hard Rock is encountered from 1.5 m to 2.5m below G.L. (Top layer being good soil)

Hard Rock Foundation with chimney for Normal Soil

WBSEBEA - 29

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15. Where hard rock is encountered from 1.5m to 2.5 m below G./L. (Top layer either in Black cotton) soil or fissured Rock)

Hard Rock Foundation design with chimneys designed for wet black cotton soil.

16. Where fissured rock is encountered at the bottom of pit (with black cotton soil at top)

Composite Foundation

17. Where hard rock is encountered at bottom with water and black cotton soil at top and hard rock layer depth is less than 1.5 m.

Hard Rock

18. Sandy soil with clay content not exceeding 10%

Dry Sandy soil foudation

19. Sandy soil with water table in the pits

Wet sandy soil design to be developed considering the depth of water.

20. Where top layer upto 1.5 m below G.L. is normal dry soil and thereafter hard soil/murrum

Normal dry with undercut

21. Where bottom layer is marshy soil with top layer of good soil/fissured rock/black cotton

Soil investigation is to be carried out and special foundation design to be developed.

22. Where the top layers are a combination of clinker mixed with firm soil, gravel and stone chips upto 60% of foundation deapth from ground level followed by hard murrum

Normal dry with undercut

23. Where top layers are combination of hard murrum, soft rock etc. followed by yellow/black clayee soil

Special foundation design is to be developed after carrying out soil investigation.

Any other combination of soil not covered above shall require development of special foundation design.

WBSEBEA - 30

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TOWER FOUNDATION DESIGN CALCULATION 400 KV D/C Transmission line Tower type : "DB" Design loads (Limiting / Ultimate) (inclusive of overload factor 1.2) Description

Normal Condition (Reliability) (Kgs)

Broken Wire Condition Security (Kgs.)

Down thrust uplift side thrust (T) side thrust (L)

165598 140917 5907 825

154376 130185 8283 4983

Tower Slopes : TAN 0=0.192570 True length factor - 1.036 Soil/rock data : Unit wight of dry spoil - 1440 kg/cu.m Unit weight of wef soil = 940 kg/cum Unit weight of dry fissured rock = 1700 kg/cu.m Unit w eight of wet f issured rock = 940 kg/cu.m. Unit weight of hard rock = 1440 kg/cu.m. Limit bearing capacity (dry locations) ; 27350 kg/sq.m. Limit bearing capacity (wet locations) : 13675 kg/sq.m. Limit bearing capacity (fissured rock locations) : 625000 kg/sq.m. Limit bearing capacity (hard rock lcations) : 125000 kg/sq.m. 225

LUSTRATION NO. -1 ESIGN OF WET TYPE FOUNDATION

C.L

Volume of Concrete (Cu.m.) :

= 11.861

1740 4690

Www

Y

Y X

1350

100 250

X

5190

WBSEBEA - 31

30° 367

50

1.347 2.694 6.106 0.605 1.109

3000 2400

= = = = =

1500

650 SQ.

200

5.192 x 0.050 5.192 x 0.100 0.25/3 (5.192 + 4.692 + 5.19 x 4.69) 1.742 x 0.2 0.652 x 2.625

866

G.L

15°

Lean Concrete (1

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2

0.65 x 0.225 x 2400 (11.681 - 0.095) x (2400-1440) 0.652 x 1.5 x (2400-1440) (11.861 - 1.347-0.095-0.634 x (1400-940)

Compression = 228 = 11295 = = 11523

Uplift 228 608 4501 5337

3.0. Dry Soll Volume : (Cu.m.) = 2 2 A1 = 5.19 + 4 x 5.19 x 0.362 + 3.14 x 0.362 A2 = 5.192 + 4 x 5.19 x (0.866+0.362) + 3.14 x (0.866+0.362)2 V = (1.5/3) (34.857+57. 160+ (34.857 x 57.160)

= 34.857 = 57.160 = 68.327

4.0. Wet Soil Volume : (Cu.m) 5.192 x 1.45 5.19 x 0.362 x2 x 1.35 3.14/3 x 0.3622 x 1.35

= 39.057 = 5.069 = 0.185 44.311

Check for Uplift Resistance Against Uplift = 68.327 x 1440 + 44.311 x 940 + 5337 = 145380 kgs. F.O.S. (NC) = 145380 / 140917 = 1.032 > 1.0 Hence O.K. F.O.S. (BWC) = 145380 / 130185 = 1.120 > 1.0 Hence .O.K. Moment due to side Thrust at Foundation Toe Normal Condition (Transverse Side Thurst) Side thrust force = (F) = 1/2 x w x h2 x 83 x 1 +

SinØ ———— 1-SinØ

Where W = 940 kg/m3 Ø = Angle of Earth Frustum = 150 B3 = 0.65 1+Sin1590 F = 1/2 x 940 x (h)2 x —————— x 0.65 1–Sin150 n = (F/518.8) F1 = ST = 5907 kgs h = (5907/ 518.86) = 3.374m Since h > (2.4.0.5) i.e. 1.9 m depth. Resisting and force F = 518.86 x 1.92 = 1873.09 kg Momenet due to side thrust at the base of the footing = 590 x (2.95 + 0.225) - 1873.09 x (0.55 + 1.9/3) = 16538.85 kg m WBSEBEA - 32

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. Normal Conditions (Longitudinal Side Thurst) Side thurst force = (F) 1/2 x w x h x B3 x 1+SinØ ———— 1/sinØ W = 940 kg/m3 Ø = Angle of Earth Frustrum = 150 B3 = 0.65 m 1+Sin1590 F = 1/2 x 940 x (h)2 x —————— x 0.65 1–Sin150 h = √ (518.86) F1 = Sl = 825 Kgs h = √ (825/518.96) = 1.261m Since h < (2.4-0.5) m therefore the soil pressure will only be mobilised in 1.261 m depth from root of the chimney. Resisting soil force F = 518.86 x 1.2612 = 825kg Moment due to side thrust at the base of the footing = 825 x (2.95 + 0.225) - 825 x (0.55 + 1.261/3) = 1818.85 kg m 6.3 Broken Wire Condition (Transverse Side Thrust) 1+SinØ Side thrust force = (F) = 1/2 x w x h2 x B3 x ———— 1-SinØ Where W = 940 kg/m3 Ø = Angle of Earth Frustrum = 150 B30 = 0.65 m 1+Sin150 F = 1/2 x 940 x (h) x —————0 x 0.65 1-Sin15 2

h = √(f/518.86) F1 = ST = 8283kgs h = √(8283/518.86) = 3.996m Since h > (2.4.0.5) m therefore the soil pressure will only be mobilised in (2.4-0.5) i.e., 1.9m in Resisting soil force F = 518.86 x 1.92=1873.09 kg. Moment due to side thrust at the base of the footing = 82830 (2.95 + 0.225) - 1873.09 x (0.55 + 1 .9/3) = 24082.70 kg m

WBSEBEA - 33

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Broken Wire Condition (Longitudinal Side Thrust) 1+SinØ Side thrust force= (F) = 1/2xwxh2 x B3 x ———— 1-SinØ

Where W - 940 kg m3 Ø = Angle of Earth Frustrum = 150 B3 = 0.65 m 1+Sin150 F = 1/2 x 940 x (h)2 x ———— ox 0.65 1-Sin15 h = √(F/518.86) F1 = SL = 4983Kgs h = (4983/518.86) = 3.099m Since h> (2.4-0.5) m therefore the soil pressure will only be mobilised in 1.9 m depth. Resisting soil force F=518.86 x 1.92 = 1873.09 kg Moment due to side thrust at the base of the footing = 4983 x (2.95 + 0.225) - 1873.09 x (0.55 + 1.9/3) 13605.2 kg m 7.0.

Check for Bearing Capacity 165598 / 1.036 + 11523 2 x (165598/1.036) x 0.192570x0.6 NC = —————————— + —————————————— 5.192 1/6 x 5.193 16538.86 1818.85 + ————— + ————– 1/6 x 5.193 1/6 x 5.193 = 6362 + 1585.3 + 710 + 78' = 8736 kg/m2 < 13675 kg/m2

Hence O.K.

154376 / 1.036 + 11523 2 x (154376/1.036) x 0.192570 x (0.6) BWC = —————————— + ——————————————— 5.192 1/6 x 5.193

24082.70 + ——————— 1/6 x 5.193

13605.2 + ————— 1/6 x 5.193

= 9056 kg/m3 < 13675kg/m2 Hence O.Kl.

WBSEBEA - 34

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Design of chimney A) Compression with bending Area of steel in compression ASC = 24 x ∏ /4 x (2.0)2 = 75.40 cm2 percentage of steel = p = ASC / B32 x 100 : B3 = 65 cm = 1.785 p/fck = 1.785/15 = 0.119 Normal Condition Puc = 165698 kgs = 1624516N Puc 1624516 ——— = ————— = 0.256 fck.bd 15x650x650 d' = 50(20/2) = 60 d = 650 therefore d'/d = 0.10 As per chart 44 of Sp. 16 For the values of Puc/fckbd Mux1/fckbd2 = 0.65 → Mux1

= 0.256 & p/fck = 0.119 = 0.165 x 15 x 650 x 6502 = 679.7 x 106 N-mm = 679.7 kN-m

Also Muy 1=679.7 kN-m From the calculation shown in $6.0 Moment at the root of the chemney Mux = 5907 x (2.4+0.225) - 187309.09 x (1.9/3) = 14320.21 kgm = 140.5 kN m Muy = 825 x (2.4 + 0.225) - 1873.09 x (1.9/3) = 1818.88 kg m = 1 7.84 kN m Ref : Clause 38.6 of IS-456-1978 PUZ = 0.45 x fck x AC + 0.75 fy ASC = 0.45 x 15 x (650)2 + 0.75 x 415 x (24 x ∏ /4 x 202) = 5198650.2 N = 5198.65 kN PUC = 165598 Kgs = 1724.5 kN PUC —— PUZ

1624.5 = ———— = 0.3125 5198.65

for PUC / PUZ = 0.3125; ∝ n = 1.1875 ∝n ∝n (MUX) ——— MUX1)

[

[

(MUY) ——— (MUY1)

1.1875 140.50 ——— 679.7

[

= 0.154 + 0.013 = 0.167 < 1.0 Hence O.K. WBSEBEA - 35

+

[

1.1875 17.84 ——— 679.70

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. BROKEN WIRE CONDITION PUC = 154376 kgs = 1514.4 kN PUC / fckbd = 1514.4 x 1000 / 15 x 650 x 50 = 0.239 p/fck = 0.119 As per chart 44 of SP 16 MUX 1/fckbd2 = 0.167 MUX1 = 0.167 x 15 x 6502 = 687.90 x 106 N-mn = 687.90 kN-m Also MUY1 = MUX1 = 687.90 kN-m From the calculation shown in $ 6.0 Moment at the root of the chimney Mux = 8283 x (2.4+0.225) = 1873.09 x (1.9/3) = 20557.21 kg m = 201.67 kN m Muy = 4983 x (2.4 + 0.225) - 1873.09 x (1.9/3) = 11894.71 kg m = 116.69 kN m PUZ

= 5198.65 kN

PUC/PUZ = 1514.4/5198.65 = 0.2913; ∝ n = 1.152. ∝n

[

(MUX) ——— (MUX1)

∝n +

[

(MUY) ——— (MUY1)

1.152 =

[

201.67 ——— 687.90

= 0.243+0.129 = 0.373 < 1.0 Hence OK Tension with Bending Normal Condition PUt = 140917 kgs = 1382396 N Put/fckbd = 1382396 / 15 x 650 x 650 = (-) 0.22 P = 1.785 p/fck = 0.119 From Chart 79 of SP 16 Mux 1 / fckbd - 0.085 Mux 1 = 350 15 kN m Muxc 1 = Muy 1 = 350.15 kN m Mux = 140.5 kN m Muy = 17.85 kN m

WBSEBEA - 36

1.152 +

[

116.69 ——— 687.90

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. As per c1.38.6 of IS : 456 : 1978 ∝n

[

∝n

[

(MUX) ————— (MUX1)

(MUY) + ————— (MUY1

< 1.0

∝ n = 1.0 for tension with bending

[ [

[

(MUX) ——— + (MUX1)

(MUY) ———— (MUY1)

140.5 17.85 ———— + ———— 350.15 350.15

[

= 0.452 < 1.0 Hence O.K. BROKEN WIRE CONDITION Put

= 130185 kgs = 1277.1 kN Put/fckbd = 1277115/15 x 650 x 650 = (-) 0.202 P-1.785 p/fck - 0.119 d/d = 0.10 From Chart 79 of S P 16 ...... Mux 1 = 370.75 kN m Mux 1 Muy 1 = 370.75 kN m Mux = 201.67 kN m Muy = 116.7 kN m As per c1.38.6 of IS-456.-1978 ∝n

[

(MuX) ———— + (MUX1)

[

(MUY) ————— (MUY1)

∝n < 1.0

an = 1.0 for tension with bending (MuX) ———— + (MUX1)

[

(MUY) ————— (MUY1)

[

201.67 116.70 = ———— + ——— 370.75 370.75 = 0.858 < 1/0 < 1.0 Hence O.K.

WBSEBEA - 37

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Design of Base Slab Design Bearing Pressure = (P/A) + (P.ex / Z) + MAX (ST moment, SL moment) / Z = 6362 + 1585.3/2 + 710 = 7865 kg / m2 = 0.07715 N/mm2 d1 = Eff. depth at Section XX = 550-50-6-8 = 476 mm d2 = Eff. depth at Section YY = 350-50-16-8 = 276 mm

a)

Compression Reinforcement (i) Bending Moment at Section X-X Bearing Pressure = 7865 kg/m2 = 0.07715 N/mm2 MUX1 = 0.077 15 x (B-B3)2/8 x 5190 = 0.07715 x (5190-650)2 / 8 x 5190 = 1031708 030 N-mm = 1031.6 kN m MU, LIM = 0.36 Xu, max/d) (1-0.42 xu, max/d) bd2 fck As per C1.37.1 f of IS - 456 for Fe 415 grade steel Xumax/d = 0.48 Mu.LIM = 0.36 x 0.48 (1-0.42 x 0.48) x 1740 x (476)2 x 15 = 815.8 kNm < 1 031.7 kNm Mux1/bd2

= 1031.7 x 106 / (1740 x 4762) = 2618 > 2.06

Hence section to be designed as doubl reinforced reinforced section. d'/d = 50+16+8) / 476 = 0.15 From table 49 of SP 16 Pt = 0.8956, Pc = 0.192 Hence Ast = (1740 x 476 x 0.8965) / 100 = 7418 mm2 Provide 37 bars of 16 mm dia. Ast provided = 7437 mm2 > 7418 mm2 Asc = (1740 x 476 x 0.192) / 100 = 1590.2 mm2 Provide 8 bars of 16 mm dia.

WBSEBEA - 38

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. This is the minimum reinforcement to be provifded at sectionX-X for uplift. Bending Moment at Section Y-Y Muy 1

= 0.07715 x (5190-1740)2 x 5190 / 8 = 595.73 kNm

Muy1/bd2 = 595.73 x 106 / (4690 x 267)2 = 1.67 < 2.06 Hence section to be designed as singly reinforced section. From table 1 of SP 16 Pt = 0.546 Hence Ast = (4690 x 276 x 0.546) / 100 = 7068 mm2 Provide 37 bars of 16 mm dia. Ast provided = 7437mm2 > 7067 mm2 Uplift Reinforcement Bearing Pressure P2

= 140917/(5.192-0.652) = 5314.9 kg/m2 = 0.052139 N/mm2

Bending Moment at Section X-X MUX2

= 0.052139 x (5190.650)2/8 x 1000 = 134333520 N mm/m

MUX2 = 0.87 x 415 x Ast x 476 (1-Ast 415/1000 x 276 x 15) Ast = 820.81 mm2 / m-width = 8.21cm2 / m-width Ast reqd 8-21 x 1.74 =14.29 cm2 Provide 8 bars of 16 mmφ Ast. Provided = 16.08 cm2 > 14.29 cm2 Hence depth provided at Section X-X is ok. Bending Moment at Section Y-Y = 0.052139 x (5190-1740)2 / 8 x 1000 = 77573055 N. mm/m = 0.87 x 415 x Ast. x 276 (1-Ast x 415 / 1000 x 276 x 15) = 850.9 mm2 / m-width = 8.51 cm2 / m-width Ast. reqd. 8.51 x 4.69 = 39.91 cm2 Provide 22 bars of 16 mm φ Ast Provided - 44.22 cm2 > 39.91 cm2 Hence depth provided at Section Y-Y is ok. MUY2 MUY2 Ast

WBSEBEA - 39

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. Check For One Way Shear At S ection X-X Design bearing Pressure p-07715 N mm2 B-B2 Shear force = V1 = ———— - dt x p 2 = 0.07715 x [(5190.650) /2-476] x 1000 = 138407 N/m width Shear Stress = 138407 / 476 x 1000 = 0.291 N/mm2 % of Steel (p) = (Ast/bd) x 100 = (74.37 x 100) / (5190 x 476) x 100 = 0.301 As per table 13 of IS:456-1978 Allowable Shear Stress = 0.3806 N/mm2 > 0.291 N/mm2 Hence O.K. At Sec Y-Y p=0.07715 N/mm2 B-B2 Shear force = V2 = ———— - d2 x p 2 0.07715 x [(5190-1740) / 2.276] x 1000 = 111790 N/m Shear Stress = 111790 / 276 x 1000 = 0.4050 N/mm2 Ast/ bdx 100 = 74.37 x 100 / (5190 x 276) x 100 = 0.5192 Allowable Shear Stress = 0.468 N/mm2 > 0.405 N/mm2 Hence OK. d)

Check for Two Way Shear At Section X-X p = 0.07715 N/ mm2 Shear force = V2 (B2-(B3+D1)2] x p = 0.07715 x [51902 - (650 + 476)2 ] = 1980304 N Shear Stress = 1980304 / 4 x 476 [650+476) = 0.924 N/mm2 Allowable Shear Stress = 0.25 x (15)½ = 0.968 N/mm2 > 0.024 N mm2 Hence OK.

WBSEBEA - 40

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. At Section Y-Y p = 0.07715 N/mm2 Shear force = V2 (B2-(B3+D1)2] x p = 0.07715 x [51902 - (1740 +276)2 ] = 1764563 N Shear Stress = 1764563 / 4 x 276 [1740+276) = 0.793 N mm2 Allowable Shear Stress = 0.25 x √15 = 0.968 N/mm2 > 0.793N mm2 Hence OK. e)

Check Against Uprooting of Stub : Design Uplitt = 140917 Kgs. Stab section 200 x 200 x 16 Stub depth below GL = 2800 mm Ult. Load resisted by stub in slab due to Bond Us = [D x (X x 2.0 + (X-Ts) x 2.0) Npx (X+ (X-Ts)) x k] x s Where X = flange width of stub. D = Depth of slub in stub s = Ultimate permissible bond stress between stub & concrete Ts = Thickness of stub section. Np = No. of cleat pair (Pair consists of outer and inner cleats) k = Flange with of cleat section Us = (40 x (20 x 2 + (20-1.6) x 2) -3x (20+(20-1.6) x 11) x10 = 18048 x kg Ultimate permissible bearing stress in concerete = 68.84 kg/cm2 Use outer cleat = 3 nos. 110 x 110 x 8 - 400 mm long Use inner cleat = 3 nos. 110 x 110 x 8 - 250 mm long provide 4 nos. of 16 dia. bolts per cleat pair of 5.6 grade resisted by cleat in bearing Uc = bx (Lo+Li) x Np x (k-Ct) Where b/ = Ultimate Bearing pressure in concrete Lo = Length of outer cleat Li = Length of Inner cleat Ct = Thickness of cleat Section. Uc = 68.84 x (40 + 25) x 3 x (11–0.8) = 136923 kg (i)

WBSEBEA - 41

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Ultimate shear strength of bolts Ub= Total no of bolts x 2.0 x 2.01 x 3160 (considdering M-16 bolt grade 5.6 & double shear for cleat connected in pair) = (4x3) x 2.0 x 2.01 x 3160 = 152438 KG ..... (ii)

Stimate bearing strength of blolt in stub or cleat = = =

Total nos. bolts x 1.6 x (Ts or 2 x Ct) x 5200 take Ts or 2 x Ct which ever is less (4x3) x 1.6 x 1.6 x 5200 159744 kg...... (iii)

Effective strength of stub and cleat = = =

f)

Us + Least of the strength of case (i) (ii) (iii) 18048 + Least of the strength of case (i) (ii) (iii) 18048 + 136923 154971 kg which is more than Ult. Uplitt = 140917 kg (Hence safe)

Check For Bond Design bearing pressure = 0.07715 N/mm2 (5190-650) Maxm. Shear force = —————— - 476 x 5190 x 0.07715 2 = 718333N As per Appendix - E or IS, 456-1978 Xu/d = 0.87 fy Ast. / 0.36 lak bd 0.87 x 415 x 7437 = ————————— 0.36 x 15 x 5190 x 476 = 0.2013 j = 1-Xu/d x 1/3 = 1–0.2013/3 - 0.933 Bond Stress = 718333/0.933 x 476 x 37 x Π x 16 0.877 N/mm2 > 1.6 N-mm2 Hence OK.

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Check for Sliding F1 = 1/2 x 1.5 x 6480 x 0.65 F2 = 1/2 x (2395 + 3832) x 0.9 xc 0.65 F3 = (0.2/2) (3832 +4151) x 1.74 F4 = (0.25/2) (4550 + 4151) x (4.69+5.19)½ F5 = (0.1/2) (4550 + 4710) x 5.19

= = = = = =

3159 1821 1389 5373 2403 14145

F.O.S. in NC = 14145 / 5907 = 2.40 > 10 F.O.S. in BWC = 14145 / 8283 = 1.71 > 1.0 Hence O.K. Check for Overturning Resultant Side Thrust (i) Under NC (ii) Under BWC

= = = =

(59072 + 8252)½ 5964 kg (82832 + 49832)½ 9666 kg

Total overturning Moment (i) Under NC = (140917/1.036) x (5.19/2-5.19/6) + 5964 x (2.95+0.225) – 5338 x (5.19/2-5 a9/6) = 245016 kg mm (ii)

Under BWC = (130185 / 2.036 x (5.19/2.5 19.6) + 9666 x (2.95 + 0.225) = 5338 x (5.19/2 - 5.19/6 = 238849 kg. m Total Resisting Moment = 1/2 x (68 327 x 1440 + 44311 x 940) + (5/6 x 5.19) = 3028.43 kg m Factor of Safety Under NC = 3028.43 / 245016 = 1.236 >1.0 Under BWC = 302843 / 238849 = 1.268 > 1.0 Hence O.K.

10.

Quantities per Tower Concrete Volume Excavation Volum Reinforcement

42.06 m3 + 5.39 m3 (M15) (M10) 361.68 m3 4962 kgs

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3.0. 13.1.

Reinforcement Detail Barbending Schedule Sketch

Length (mm)

BarØ (mm)

No. of Bas

nit wt. Wt/Length Wt/Tower (kg/m) (kgs) kgs

5090

5090

16

76

1.58

611.21

2444.84

26090

16

16

1.56

68.00

272.00

5352

16

44

1.58

372.07

1488.28

3350

20

20

2.47

165.49

661.96

2307

6

13

0.22

6.60

26.39

Total

4893.47

1640 425 100

100 4590

281 100

100 3000

350 550

550

4894 kgs

13.2 Reinforcdment Sketch.

225

Stub

C.L

G.L

Bar Mkd. 'D', 4-20

bars

Bar Mkd. 'E', 6 mm Ø bars 250 c/c

100 250

Bar Mkd. 'B', (8+8) bars of 16

Bar Mkd. 'C', (22+22) bars of 16

Bar Mkd. 'A', (38+38) bars of 16

50

(Stub lv. below G.L)

3000 2800

650

2088 5628

kg. meters to be written in pressure design

6228

REINFORCEMENT

WBSEBEA - 44

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W

W

W

W

W

W W WBSEBEA - 45

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W W

W

W W

WBSEBEA - 46

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W

W W WBSEBEA - 47

W

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. CLASSIFICATION OF SUB-STATION a) Step-up sub-station b) Primary Grid Sub-station c) Secondary Sub-station d) Distribution Sub-station. e) Bulk supply & Industrial Sub-station f) Mining sub-station g) Mobile sub-station h) Switching sub-station STANDARD BAY SPACING

System Voltage (kv)

Bay Spacing (m)

33

6.0

66

7.6

132

10.4

220

17.0

440

27.0

WBSEBEA - 48

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WBSEBEA - 49

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. Bus-bar Material : Strain Bus-bar 72.5 kv. 30/7/3.00 ACSR Panther 145 kv 30/7/4.27 ACSR moose 245 kv 54/7/3.53 ACSR twin 420 kv 54/7/03.53 ACSRMoose or Quad. Rigid bus-bar Voltage

Diameter of pipe IPS (iron pipe size)

wt/m

Current carring capacity

33 kv 66 kv. 132 kv. 2 20 kv 400 kv

1.5 inches 2.0 inches 2.5 inches 3.0 inches 4.0 inches

1.3 1.90 2.97 3.89 7.68

1160 1440 1950 2350 3950

Chemical composition Copper - 0.05 % Magnisium - 0.4-0.9% Silicon - 0.3-0.7% (of Grade 63401wp) Iron, max - 0.5% Managanese, Max - 0.03% Aluminium - Remainder Ultimate tensile strength : 20.5 kg/mm2. Typical Power Transformer ratings : 33/11 kv 5/6.3 MVA 1/1.5/3/3.15 66/11 kv 5 MVA. 66/33/kv 6.3/7.5 MVA. 132/33 kv 12.5, 20, 3 1.5, 50 MVA 132/66 kv 10, 20, 31.5 MVA. 220/132 kv 100, 150, 160 MVA. 400 / 200 kv 3x105 MVA. √3VI Fault mva = ————, where 106

v = Service voltage I = Fault current

Typical ratings of ABCB (Air blast .... breaker) 12kv 250 MVA 22kv 500 MVA 145kv 3500 MVA 245kv 10000 mva 420kv 35000 MVA

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Typical rating of SF6 breaker Rated voltage (kv) Rated Current (A) Rated s/c current (kv) Breaking Capacity (mva)

36 1250 25 (3sec) 750

72.5 1250 25 (3s) 1000

145 1600 31.5 (3s) 7900

245 1600 40(3s) 16974

420 2000 40(1s) 29098

Rated current of disconnect switch 200, 400, 630, 800, 1250, 1600, 2000, 2500, 3150, 4000, 5000, 6300, 8000, 10000 Amps (IS : 1 818-1972) Rated Voltage : 3.6, 7.2, 12, 24, 36, 72.5, 123, 145, 245, 420 kv. Typical rating of disconnect switch Rated Voltage (kv) 36 72.5 145 245 420

Rated Current (A) 600/800 800 1250/1600 1600 2000

Rated Compressed air pressure 5, 10, 15, or 20 kg/cm2

WBSEBEA - 51

Ratedf s/c current (kA) 20 (3s) 31.5 (3s) 31.5 (3s) 40 (3s) 40 (3s)

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F.L. CURRENT OF TRANSFORMERS IN AMPS. K.V.A. 25 50 63 75 100 150 160 200 250 300 315 500 10 15

3 " " " " " " " " " " " S "

440 V 32.80 65.61 83.06 98.11 131.22 196.82 262.43 328.04 393.66 636.08 21.789 32.60

11000 V 1.31 2.62 3.32 3.94 5.25 7.87 8.4 10.50 13.12 15.75 16.53 26.24 1.574 2.36

433 V 33.34 66.67 84.4 100.00 133.34 200.00 213.34 266.68 333.35 400.02 420.00 666.7 -

COMPARISON OF PROPERTIES OF AMORPHOUS METAL AND CRGO STEEL KVA

10

Number of Phases

1

15

No-Load Loss (Watt) Amorpheouse Core Transformer

CRGO Core Transmfermer

10

40'

15

60

25

3

25

100

63

3

45

180

100

3

60

260

AMORPHOUSE CORE DISTRIBUTION TRANSFORMERS Transmission and Distribution losses in India is about 21% of the generated energy. Every effort will have to be made in this context to reduce these losses so that the existing generation and Transmission and Distribution system can be used to feed more loads. The no-load loss of the Distribution Transformer is of great importance since these are present even when the transformer is under no-load conditions. The use of amorphous metal in place of CRGO steel for the transformer core reduces the no load loss (Core loss) of the transformer by approx. 75%. Thus the Amorphous core Transformers save energy and there by conserve resources.

WBSEBEA - 52

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I

O BC O

I

O

STORE & TOOL ROOM 2400x2100

F

6000

9000

OLTC PANEL

BAT FAN

33 kV

1

W.C 2400x1400

6400

O

1200

Outgoing 33kv. Line

CABLE DUCT (900 x 900)

F

1200

VERANDAH 2400x2000

7500

4500

INCOMING 33 KV LINE 1200

1050

R O A D

1200

1200

OUTGOING 33 KV LINE (FUTURE)

1050

1050

Inco

Outgoing 33 kv line

6600

2100

P U C C A

1200

(Future)

LAS 2100

OUTGOING 33 KV LINE

1050

1200

1200

Out

TRANSF 4300

4300

2400

3100

3700

ISOLATIN

ISOLATIN

WBSEBEA - 53

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1050

1200

1200

1050 4500

Outgoing 33kv. Line

2400

3100

6400

Fuse

4500

3600

4500

L.A.S.

2500 4500

2400

3100

3700

3500

3700

CONTROL ROOM

3100

4500

7500

7500

4600

INCOMING 33 KV LINE 1200

1200

1050

6600

2100

1200

1200

OUTGOING 33 KV LINE (FUTURE)

1050

1050

1050

1200

1200

2100

OUTGOING 33 KV LINE

2500 4500

4500

2400

WBSEBEA - 54

3100

3700

3500

3700

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11kv. FEEDER

CONSTRUCTION STANDARDS

6400

6400

L-1

NOTES:

INCOMING 33 KV LINE

1. 33 KV circuit breaker (shown dottod) is to be used only when there are two transformers each with a capacity of 5 MVA or above.

1750 3500

2. Conductors used for 11 KV and 33 KV jumpers and busbars should not be less than 50 sqmm. (CE) ACSR.

3500

3. Expulsion type fuses (preferablyemploying turranol tubes) should preferably be used for proper protection of transformers. 4. The supports will not be guyed but may be suitably concreated.

OUTGOING 33 KV LINE (FUTURE)

6. Details of 33 KV incoming/outgoing arrengement (shown dottod) will depend upon the nature of the sub-station (terminal or

OUTGOING 33 KV LINE (FUTURE)

FUTURE

5. 33 KV lighting arresters will be of station type.

11 KV FEEDERS

intermidiate etc.) & the State Electricity Board may adopt their Standard practices. 7. Circuit breakers on 11 kv side of the transformers will not be provided if the transformer capacity less than 1.6 mva each. In such cases intermediately structures with post insulators (shown dotted) may be used.

850

900

900

850

8. Cables in the switchyard may be either buried or carried in pucca trenches State Electricity Board.

TRANSFORMER ISOLATING SWITCH WITH ARCING HORN

ALL DIMENSION ARE IN mm

ISOLATING SWITCH WITHOUT ARCING HORN FUSE LIGHTING ARRESTER

(OUTDOOR 11 KV SWITCHGEAR)

33 KV CIRCUIT BREAKER 850

900

900

850

11 KV CONTROL KIOSK

WBSEBEA - 55

Scale: 1:100

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BASIC TECHNOLOGY AND FUNCTIONAL DETAILS OF TRANSFORMERS AND ITS ACCESSORIES. 1

2. A.

(a) (b)

INTRODUCTION : Transformer is a static equipment being one of the major corner stones in the fabric of any electric power supply system used for transmission and distribution of electric power by stepping up or stepping down the voltage in transmission and distribution networks. It is very high value equipment and repid expansion of power system increases the population of transformer of various capacities and categories but broadly classified as power and Distribution transformers. Capital out lay behind erected transformers is anything from 8-25 percent of total assets in use in Electricity Boarda. Transformers have ordinarily an active life of 25 or 35 years according as it is a Power or Distribution transformer, though recent amendment has been made for 25 years of active life for both type of transformers. It is alarming to note that failure of transformers is as high as 10-20% even more in our country and has increasing trend year after year on National Scenarie compared to about 1-2% failure rate in advanced Countries. Failure rate of Distribution transformers is much more than power transformers. However, failure of transformers is one of the reasons behind economic set back of SEBs. If a transformer is manufactured properly tested properly commissioned properly and maintained properly with care, it is very difficult that a transformer will have its prematured death, which should be considered to be a crime. BASIC TECHNOLOGY : DESCRIPTION & CLASSIFICATION : The main functional parts of a transformer are core and windings. Cores are normally m ade of CRGO steel of M4 Grade. Another new variety of GRGO steel is Hi-B steel. The major features of this material is the lower Core loss in higher managetic fields, reducing exciting current and reduced noise due to better manetisation and managetostriction characteristics. The most recent development is Amorphous steel of Metglass in USA for distribution transformers. Although it can not be excited to a higher flux density like GRGO steel, but even with its use in low flux density, the saving in no load loss is very advantageous to the system. Windings are made of copper or Aluminium, with LV winding near to core surrounding which HV winding is arranged. The main problem of designing high voltage windings is the voltage distribution and electrical stress developed during lightning and switching surges. The radial and excial forces during unbalanced faults is also a matter to be looked into for with-standing the same. In a broader sense transformers are classified according to (a) Core arrangement (b) Winding arrangement (c) Functional duty in the field. Core Arrangement : Depending on arrangement of core materials, transformers may be core type or shall type. Winding Arrangement : Depending on number of windings, transformers may be classified as two wings (Primary/Secondary) or three windings (Primary/ Secondary/Tortiary) transformers. Again a Transformer may have a single winding, a part of which acts as Primary and the rest part as secondary, called Autotransformer. In two or three windigs transformers windings are not electrically connected but are magnetically connected by magnetic flux but in Auto-transformer both primary and secondary are electrically connected as one continuous winding per phase besides having magnetic linking. In the common part of the winding, the input and output currents are superposed. The principal application of Auto transformer is incases where separation of primary and secondary winding is not essential and the voltage ratio is not great. Such application include boosters, static balancers, various, induction-motor starters and big power transformers etc. Advantages gained is a considerable saving in conductor materials, Cores and losses.

WBSEBEA - 56

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In Auto-Transformer The ratio : Conductor materials x ————————————— In Normal Transformer. V2 = 1 — ——— ............................... (1) V1 Where V1 = Primary voltage, V2 = Secondary voltage. If V1 = V2, no transformer is required. For a voltage ratio of 2 : 1, approximately 50% saving in conductor materials and Over all saving may be 65-70% of that of normal transformers. So Auto transformers are not generally used where the voltage ratio exceeds 3:1, except for motor starting duty as the advantages preponderate. So in 132/33 system normal transformer will be economical but in 132 / 66KV, 220/132KV and 400/ 220KV systems auto-transformer will be economical. However, auto-transformer have the following disadvantages. (i) Due to electrical continuity between high and low voltage circuit, higher voltages may be impressed upon low voltage circuit which needs to with-stand the same. (ii) Due to direct electrical connection disturbance of one side affect seriously the other side. (iii) Leakage flux between primary and secondary being shall, impedance is low resulting heavy fault current. (iv) The connections on Primary and secondary sides have necessarily to be same i.e. either star / star or Delta / Delta which introduces problem for changing Primary and secondary phase angles. (v) Because of common neutral both the sides have to be either earthed or insulated. (vi) It is difficult to preserve the electromagnetic balance of the windings when tappings are provided as such tappings are limited to avoid larger frame size. Inspite of all such disadvantages, auto transformers are selected for saving in cost when the voltage ratio is not high.

(i) (ii) (iii) (iv) (v) (vi)

TERTIARY WINDIG : A transformer double wound or auto-wound has minimum of two voltages size one corresponding to supply side and the second corresponding to the load side. Many a time a third winding is introduced either becauses of vector grouping or because another voltage is required at the same place to supply loads viz-132/66/11KV or 220/132/33KV etc. In either case the third winding is connected in delta formation and is known as Tertiary winding. In various transformer connections there is serious problem of third harmonic components of the magnetising current. In order that the core flux wave be a sinusoidal as well as the induced voltages, the magnetising current must includes the third harmonic component or triplen harmonics. The tertiary delts provides a short circulated path for the flow of third harmonic current which are time co-phasal in all the three legs of the system, there by eliminating third or multiple of third harmonic pressures from the star connected primary and secondary windings. The neutral points of such windings are, therefore, stable and can be earthed without any ill effects to the transformer on the system. In addition territory winding helps :To reduce unbalancing in primary phases due to unbalanced loads in secondary phases.' To supply an auxiliary load in addition to main load. The short time thermal rating should be limited to 1/3rd that of the main windings. Limitation of fault current depending on impedances between tertiary and main windings. In star/star transformers to allow sufficient earth fault current to flow for the operation of CBS. As a voltage cell in a testing transformers. To interconnect three supply systems operating at different voltages. However, tertiary winding shall be used to supply local loads only, length of readers shall be limited to 5 KM as far as practicable cable.

WBSEBEA - 57

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. (c) Functional Duty : Transformers for urban and rural supply usually termed as Distribution Transformer should be worked with lower flux density (1.55 Tesla or less) on account of keeping minimum core loss and magnetising KVA as these transformers are in contineuous operation on small loads. Performance of these transformers should be judged by "All Day Efficiency" i.e. ratio of out-put in KWH to input in KWH for 24 hours. On the other hand Power Transformers may be cut out of Circuit at times of light loads, whereas a Distribution Transformer is continuously energised. So power transformers can be operated at high flux density (1.7 to 1.8 Tesla) and their performance can be judged by "Commercial Efficiency" i.e. ratio of output in watts to the input in watts. (B) CHOICE BETWEEN THREE PHASE UNIT VS BANK OF SINGLE PHASE UNIT : Failure of power transformers puts a difficult situation of Power interruption which is a time taking process for replacement of such a costly equipment. More over, even if a spare transformer is available, transportation, erection, commissioning testing etc. are all time taking process. Since the transformer is the most expensive single item and improved technique of manufacture and reliable testing, it is now considered a dependable equipment, as such keeping spare transformers to meet up such odd events is not at all economically viable. Now, suppose a total power P is to be transmitted from a Grid Sub-Station. What will be the choice of transformer(s) to be installed in the Sub-Station, so that there will be minimum interruption of Power in case of failure of transformer. The choice may be in the following three ways. (i) I F C1 = Cost of a single three phase unit of three phase capacity - P. (ii) C2 = Cost of two transformers each having capacity P2 running in parallel. (iii) C3 = Cost of 4 single phase units of each capacity P/3 having one spare unit. Then, C : C2 : C3 : 0.7 : 1 : 1.2 -= 7 10 : 12. It is evident that a single phase unit of capacity P will be less costly. Due to additional Civil work, assessors like OLTC, Bushings etc. Cost will gradually increase for two units and four units. The best choice will be two units of capacity P/2 running in parallel because of the fact that failure of one unit will maintain atleast 50% Power supply and by over loading 60-70% Power can be maintained for a short time, though more costly than a single three phase unit when entire Power supply will be interrupted. In case of 4 Single phase units of each capacity P/3, advantages gained is that entire power system can be restored quickly by replacement of spare unit, but is much more costly, at the same time spare unit will be idle inventory and the accumulated cost of entire country will be a huge financial burden. However, single phase units have field application where transportation is a problem because of weight and dimensions etc. 3. LOSSES IN A TRANSFORMER : (a Core and copper losses : In an ideal transformer, Power fed to the primary circuit is equal to the Power received from the secondary circuit. But hardly can we meet this requirement. A considerable amount of Power fed to the Primary circuit is lost as (i) Core loss to maintain the magnetic circuit (ii) Copper less in the form of heat. So the Power received from the Secondary circuit is always less less than that fed to the Primary circuit. The core or iron loss of a transformer is more or less fixed but the cu-loss of a transformer is variable with the load as such sometimes called as load loss. The cost of a transformer can be adjusted appreciably with the ratio of iron and cu-losses, by choice of core materials, percentage reactance or core section and section of copper conductor. Moreover allocation of losses will decide the over load capacity of a transformer within specified temperature limit. So amplication of losses in a transformer is very important towards economic functioning as well as survival. (b) Loss Capitalisation : No load loss and load loss in Distribution Transformer upto 100KVA rating in 11KV System, has been fixed in I.S. at 75oC. So these transformers are to be manufactured keeping the losses within the limits as furnished in Table - 1.

WBSEBEA - 58

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. TABLE - 1 KVA Rating of No load loss Load loss 11/0.415 KV 3-ph (Watts) with (watts) at Transformer GRGO steel core 75oC 25 63 100

110 200 290

Remarks

720 1300 1850

These losses are maximum allowable with no positive tolerance. No. weightage in price for offering lower losses.

In case of Power Transformer, the losses are not fixed by the purchaser unless, of course, the new transformer is to run in parallel with the existing ones. In order to select technically best suited and economically lowest transformer the unique method of "Loss Capitalisation" for evaluation of losses are employed in tender evaluation. In power transformer there are three losses viz (i) Iron (Core) loss, (ii) Load (Copper) loss (iii) Auxiliary losses. The auxiliary losses are the power losses of auxiliary equipment like cooling plants etc. and are considered to be a part of load loss. For the purpose of Comparison capitalised value of iron loss and load loss shall be mentioned in the specification of the purchaser. The tender shall state and guarantee the losses but shall not specify any tolerance limit for the same. Tolerance limit for no load loss is plus 10% of the guaranteed loss and that for load loss is also plus 10% of the guaranteed loss as per I.S.S. The main idea behind loss Capitalisation is that Capitalised value of the losses with I.S. tolerances shall be added with exworks price of the transformer for comparison and selecting lowest bidder and same shall be verified through testing before accepting the same. 4. PERCENTAGE IMPEDANCE : The resistance of a transformer being bery small is unimportant as such discussion will be limited to percentage reactance only. For a given ratio and voltage the size and weight of a transformer is a function of its percentage reactance. The weight is a minimum for a particular reactance called "Economical Percentage Reactance". In the case of a 220KV transformer the cost decreases slightly when the percentage reactance is increased from 10% to 16% . This is because a small percentage reactance means a large main flux requiring large cross-section of the core. As reactance is increased the core section decrease and so the overall size. The iron loss is decreased but the copper loss is increased. The ratio of copper to iron loss is appreciably increased and the total loss is slightly increased. But when the reactance is still more increased the same argument does not hold, the cost increases becauses of high leakage flux. For every voltage there would be a normal range of percentage reactance within which the cost may not very appreciably. The ranger of values in Table-2 corresponds to usual practice. TABLE - 2 Type of Transformer Range

MVA voltage (KV)

Height System Range

% Impedance

(i) Distribution

Upto -1

-

4 to 5

(ii) Industrial S/S

6 to 20

36 to 100

6 to 10

(iii) Large unit type ONAN/ONAF/OFAF

20 to 50

123 to 170

10 to 14

(iv) Large unit type ONAN/ONAF/ODAF

50 to 300

245 to 4 20

12 to 16

WBSEBEA - 59

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. While fixing percentage impedance of a transformer before procurement two points shall be kept in mind : (a) If the newly procured transformer is not intended to run in parallel with any existing transformer the percentage impedance of the transformer shall be decided within the ranges shown in the Table-2, but matching with the system network impedance to which the said transformer is going to be connected.' (b) In case the newly procured transformer is required to run in parallel with any existing transformer then the percentage impedance of the transformer to be procured shall be matched with the existing transformer. From the above it is found that percentage impedance of a transformer is very important item for economical design of a transformer. So in the tender specification the value of percentage impedance shall be properly selected and clearly mentioned. Any abnormal value will make the transformer design un-economical and unnecessary cost thereby. Considering all the facts percentage impedance of Power transformers in WBSEB system have been fixed in the range 10-12%. 5. TEMPERATURE STIPULATION : Transformers are installed outdoor without any protection against sun and rains. The maximum temperature of the Hot-spot shall be limited to 105oC with class-A insulation. Each transformer shall be capable of operating continuously at its normal rating without exceeding the specified temperature rise limits as per I.S.S. The maximum temperature of top layer of the oil inside a transformer should not exceed 60oC above ambient temperature. The life of transformer oil is halved if its temperature is 10oC above normal. If average ambient temperature is 35oC, top oil temperature should not exceed (35+60+10)oC or 85oC for Power transformers. For Distribution transformers it is (85-10oC = 75oC. 6. COOLING : The rating or power delivery capacity of a transformer can be increased by providing proper cooling arrangements, otherwise temperature limit will reach and or excessive temperature rise will damage the transformer as a hole. Natural cooling and forced cooling are employed stage by stage. (a) Natural cooling, Radiators : (i) Radiators : Transformers are generally filled with detachable radiators consisting of a series of separate circular or elliptical tubes welded at their top and bottom into header to be connected to the main tank by means of bolted, oil tight flanged joints. There are valves one at the top header, and other at the bottom one for circulation of all. The main purpose of radiators is to provide increased cooling surface for circulating oil by increasing the total tank area without increasing appreciably the oil containing capacity. Moreover, thickness of the radiators is less than that of main tank, thus saving of iron materials, reduced weight for transportation, hence reducing the cost of transformers, and decreasing foundation cost etc. So main tank is subjected to vacuum Testing but the radiators to Pressure Testing only. (b) Forced Cooling : The natural cooling is not sufficient as MVA rating of the transformers and loading increases. So different types of forced cooling arrangement have to be employed. In WBSEB specification we are employing ONAN/ONAF/ODAF type of cooling upto 160 MVA transformers. ONAN rating shall be about 50% and ONAF is about 75% and ODAF is about 100% of the rated capacity without exceeding the temperature limits (ONAN-oil Natural & Air Natural, ONAF-Oil Natural & Air Forced; ODAF-Oil Directed & Air Forced). The temperature setting of the cooler control contacts shall be generally as under : Cooling Equipotent Fans (For forced air) Pumps (For directed oil)

ON 85oCV 90oC

WBSEBEA - 60

OFF 60oC 65oC

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. 6A. OVERLOAD CAPACITY OF TRANSFORMERS : The cost of transformer as well as its performance and efficiency greatly depends upon to total quantum of loss of energy in the process of transformation. The ratio of full load copper loss to core loss is called 'loss ratio' which determine the over load capacity of a transformer. Greater the loss ratio less capable is the transformer of sustaining over loads. Over loading of oil immersed transformer is guided by BS-170/1936, BS code of practice CP1010/1959 and I.S. 6600/- 1972 for ON and ONAF Colling, represented below :Permissible Load (%) 125 150 175 200 300 Duration (Minutes) 125 45 15 10 1 However, normal transformer are, so designed that they can withstand 110% over loading for a considerable period without exceeding the temperature limits under emergency circumstances, depending on load factor. Loading cycle for traction transformer is quite different from that of normal, Power transformer due to nature of load variation in the traction system which is furnished below : (a) 50% over load for 15 minutes - during 3 hours (b) 100% over load for 5 minutes - during 3 hours (c) 50% over load for 15 minutes & 100% over load for 5 minutes - during 3 hours. The capacity of a traction transformer to withstand over load cycle pattern mentioned above is called " Non-cumulative over Load capacity" after the transformer has reached steady temperature on continues operation at full load. From detailed calculation it is found that Traction transformers has to face 165% average over loading for a period of 20 minutes and 200% over loading for a period of 5 minutes after every 3 hours and according are designed to withstand such over load. 7. MOMENTARY LOAD LIMITATIONS OF POWER TRANSFORMERS : Power Transformers in service must be capable of short circuit at normal line voltage without injury. The duration imposed as per B.S.171/1956, is 2 seconds for a transformer with 4% impedance, 3 seconds for 5% impedance, 4 seconds for 6% impedance, and 5 seconds for 7% impedance and above. Transformers with an impedance of less than 4% are called upon to withstand the affects of twenty-five times full load current for 2 seconds without injury. 8. OVER FLEXING IN TRANSFORMERS : (a) Causes of over flexing : As per present day transformer design practice, the peak rated value of the flux density is kept about 1.7 to 1.8 Tesla, while the saturation flux density of CRGD steel sheet of transformer core is of the order of 1.9 to 2 Tesla which corresponds to about 1.1 times the rated value. If during operation, a transformer is subjected to carry rather swallow more than above mentioned flux density as per its design limitations, the transformer is said to have faced over fluxing problem and consequent bad effects towards its operation and life. Depending upon the design and saturation flux densities and the thermal time constants of the heated component parts, a transformer has some over excitation capacity. I.S. specification for Power transformers does not stipulate the short time permissible over excitation, though in a round about way it does indicate that the maximum overfluxing in the transformer shall not exceed 110%. The flux density in a transformer can be expressed by B = C V/f, where, C=A constant, V=Induced voltage, f=Frequency. The magnetic fluxdensity is, therefore, proportional to the quotient of voltage and frequency (V/f). Overfluxing can, therefore, occur either due to increase in voltage or decrease in-frequency of both. The probability of over fluxing is relatively high in stop-up transformers in Power stations compared to step -down transformers in Sub-Stations, where voltage and frequency usually remain constant. However, under very abnormal system condition, over-fluxing trouble can arise in step-down Sub-

WBSEBEA - 61

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. Station transformers as well. We faced such a situation at Hizli and Egra 132/33KV Sub-Stations on 28th June, 1900 at about 3-30 P.M. during World Cup Football Tournament. Transformers of Hizli Sub-Station tripped through Differential Relay followed by Buchholz Alarm, those of Egra SubStation through differential Relay only, due to high voltage exceeding 150 KV. (b) Effect of Over Fluxing in Transformers : (i) The flux in a transformer, under normal conditions is confined to the core because of its high permeability compared to the surrounding volume. When the flux density in the increases beyond saturation point, a substantial amount of flux is diverted to steel structural parts and into the air. At saturation flux density the core steel will over heat. Structural steel parts which are unlaminated and are not designed to carry magnetic flux will heat rapidly. Flux flowing in unplanned air paths may link conducing loops in the windings, loads, tank base at the bottom of the core and structural parts and the resulting circulating currents in these loops can cause dangerous temperature increase. Under conditions of excessive overfluxing the heating of the inner portion of the windings may be sufficiently extreme as the exciting current is rich in harmonies. It is obvious that the levels of loss which occur in the winding at high excitation cannot be tolerated for long if the damage is to be a voided. Physical evidences of damage due to overfluxing will very with the degree of over excitation, the time applied and the particular design of transformer. The Table-3 given below summaryses such physical damage and probable consequences. TABLE - 3 Component involved i) Metallic support structure for core and coils

Physical evidences

Consequences

Discolouration or metallic parts and adjacent insulation. Possible carbonized material in oil. Evolution of combustible gas.

Contamination of a oil and surfaces of insulation. Mechanical weakening of insulation Loosing of structure. Mechanical structure

ii) Windings

Discoloration winding insulation evolution of gas.

Electrical and mechanical weaking of winding insulation

iii) Lead conductors.

Discoloration of conductor insulation or support, evolution of gas.

Electrical and mechanical weakening of insulation, Mechanical Weakening of support.

iv) Core laminations.

Discolouration of insulating material in contact with core. Discoloration and carbonization of organic/lamination insulation Evaluation of gas.

Electrical weakening of major insulation (winding to core) increased interlaminar eddy loss.

v) Tank

Blistering of paints

Contamination of oil if paint inside tank is blistered.

.

(ii) It may be seen that metallic support structures for core and coil, windings, lead conductors, core laminations, tank etc. may attain sufficient temperature with the evolution of combustible gas in each case due to overfluxing of transformer and the same gas may be collected in Buchholz Relay with consequent Alarm/Trip depending upon the quantity of gas collected which again depends upon the duration of time the transformer is subjected to overfluxing. This was the reason why Buchholz Alarm came in case of 31.5 MVA transformer at Hizli 132 KV Sub-Station on 28th June, 1990.

WBSEBEA - 62

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(c)

Due to overfluxing of transformer its core becomes saturated as such induced voltage in the primary circuit becomes more or less constant. If the supply voltage to the primary is increased to abnormal high value, there must be high magnetising current in the primary circuit. Under such magnetic state of condition of transformer core linear relations between primary and secondary quantities (viz. for voltage and currents) are lost. So there may not be sufficient and appropriate reflection of this high primary magnetising current to secondary circuit as such mismatching of primary currents and secondary currents is likely to occur, causing differential relay to operate as we do not have overfluxing protection for sub-Stn. transformers. That is why the power transformers of both Hizli and Egra 132 KV Sub-Station tripped on 28th June, 1990 through differential relay though there was no internal fault. Stipulated Withstand-Duration of Overfluxing for Power Transformers : Overfluxing of transformer has sufficient harmful effect towards its life which has been explained. As overflusing protection is not generally provided in step-down transformers of Sub-Station, there must be a stipulated time which can be allowed matching with the transformer design to withstand such overfluxing without causing appreciable damage to the transformer and other protections shall be sensitive enough to trip the transformer well within such stipulated time, if cause of overfluxing is not removed by this time. It is already mentioned that the flux density 'B' in transformer core is proportional to v/f ratio. Power transformers are designed to withstand (Vn/fn x 1.1) continuously, where Vn is the normal highest r.m.s. voltage and fn is the standard frequency. Core design is such that higher v/f causes higher core loss and core heating. The capability of a transformer to withstand higher v/f values i.e. overfluxing effect, is limited to a few minutes as furnished below in Table-4. TABLE - 4 v/f F= ——— vn/fn Duration of with stand limit (minutes)

1.1

1.2

1.25

1.3

1.4

continuous

2

1

0.5

0

From the table-4 it may be seen that when overfluxing due to system hazards reaches such that the factor F attains a values 1.4, the transformer shall be tripped out of service instantaneously otherwise there may be a permanent damage.' (d) Protection Against Overfluxing (v/f - Protection) : (i) The condition arising out of overfluxing does not call for high speed tripping. Instantaneous operation is undesirable as this would cause tripping on momentary system disturbances which can be borne safely but the normal condition must be restored or the transformer must be isolated within one or two minutes at the most. (ii) Flux density is proportional to V/f and it is necessary to detect a ratio of V/f exceeding unity, V and f being expressed in per unit value of rated quantities. In a tyhpical scheme designed for over fluxing protection, the system voltage as measured by the voltages transformer is applied to a resistance to product a proportionate current; this current on being passed through a capacitor, produces a voltage drop which is proportional to the functioning in question i.e. V/f and hence to flux in the power transformer. This is accompanied with a fixed reference D.C. voltage obtained across a Zener diode. When the peak A.C. signal exceeds the D.C. reference it triggers a transistor circuit which operates two electromechanical auxiliary elements. One is initiated after a fixed time delay, the other after an additional time delay which is adjustable. The overfluxing protection operates when the ratio of the terminal voltage to frequency exceeds a predetermined setting and resets when the ratio falls below 95 to 98% of the operating ratio. By adjustment of a potentiometer, the setting is calibrated from 1 to 1.25 times the ratio of rated volts to rated frequency.

WBSEBEA - 63

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. The output from the first auxiliary element, which operates after fixed time delay available between 20 to 120 secs. second output relay operates and performs the tripping function. (b) It is already pointed out that high V/f occur in Generator Transformers and Unit-Auxiliary Transformers if full exaltation is applied to generator before full synchronous speed is reached. V/f relay is provided in the automatic voltage regulator of generator. This relay blocks and prevents increasing excitation current before full frequency is reached. (c) When applying V/f relay to step down transformer it is preferable to connect it to the secondary (L.V. saide of the transformer so that change in tap position on the H.V. is automatically taken care of Further the relay should initiate an Alarm and the corrective operation be done / got done by the operator. On extreme eventuality the transformer controlling breaker may be allowed to. trip. 9. Effect of vector Grouping : (a) Vector Grouping : depending on phase difference of primary and secondary voltages, transformers are grouped as follows : (i) Group-1, Zero phase displacement - Yyo, Ddo (ii) Group-2, 180o phase displacement - Yy6, Dd6 (iii) Group-3, lag phase displacement - Dy1, Yd1 (iv) Group-4, 30o lead phase displacement - D11, Yd11 Vector Group in W.B.s.E.B. system : Previously in W.B.S.E.B. system we used transformers of Yyo vector group. But gradually since 1984 Yyo group is being replaced by Yd1 group with the help of 100 KVA, 33/0 415 KVA, ZnY Earthing cum Station Service Transformers for earthing the delta secondary system as well as for station service. The question arises why this system was adopted inspite of use of empty earthing cum station service transformers. The reasons are as follows :_ (a) Yyo connection is most economical for small high voltage transformers because the number of turns per phase and the amount of insulation is minimum as phase voltage is only of the line voltage. This connection works satisfactory only if the load is balanced. In unbalanced loads, the neutral points shift, thereby making the line to neutral voltages (phase voltages) unequal. With the complicated loading pattern in W.B.S.E.B. system as well as need for increase of transformer capacity Yyo Group Required replaced. (b) In Yd1 system, no. difficulty is experienced from unbalanced loading as in case of Yy system. Voltage wave shape is not distorted due to the flow of third harmonic current in d delta winding. (c) Yyo transformer, if one of the line jumpering is burnt cut but not touching the tower, current in one phase will be zero. It sudh as case voltage in primary and secondary sides will be balanced but currents will be highly unbalanced and there will be quick high temperature rise in transformer which will damage the same. We faced such situation at Egra and Chandrakona Road 132 KV sub-Station and introduced special protection arrangements with 3 PTS connected in Open-deltato sense one voltage sensitive relay to trip the transformer. But Y d transformer will not have such adverse eiffer. (d) Yd1 tranformer is used alongwith an Earthing Transformer. The earthing tranformer has a very low impedance during its normal operation but offers a very high impedance during falt to act as a current limitor. It is found that fault current limiter. It is found that fault current in Yd. Transformer can be reduced to approximately 1/10th of Yy transformer with both the neutrals earthed,. (e) In Grid Sub-Stations burning / melting of clamps, connectors, jumpers in a chronic problem. though we are using connector of phosphoer bronze, with the increase of faulti level, connectors of phospher bronze are also found to be not suitable. With the change over to Yd transformer alongwith earthing cum station service transformer, fault current is very much reduced. So we can use clamp and connectors of E.C. grade hard drawn extruded Almunium, which are less costly than phosper bronze and a considerable cost can be saved as well as frequent power interruptions due to replacement of clamps and connectors can be stopped. The cost of E.C. grade extruded

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Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. aluminium is nearly50% that of phospher broze. In W.B.S. E.B. system auto transformers or Yy Vector Group is in operation for voltage ratio 132/66/11 KV and 220/132/33V. In such cases Yy group has been chosen in order to avail of the economical advantage of auto-transformers discussed earlier. 10. Bushings : (i) Bushings are provided with the transformer for entry of high voltage and exit of low voltage terminals and vice-versa. Bushings are very delicate part of a transformer and as such should be specified, procured, handled and maintained with care. Frequent bursting of bushing occurs in transformers due to various reasons. (ii) At present, we are using bushings of 66 KV and above which are of oil filled condenser type hermatically sealed and 33 KV bushings are of porcelain oil filled type and 11 KV bushing are porcelain plain shed type. In general active part of the condenser bushing consists of a central metallic condoctor tube enclosed by wound bakalite paper or oil impregnated paper body or synthetic resin bond payer with aluminium foils in between the layers for field control. The innermost aluminium layer is connected to the conducting tube and the outermost to the fixing flange. A porcelain jacket is provided on the condenser bushing. The space between the paper body and the porcelain jacket is filled with highly viscuss oil with an air space below the protective hood of the bushing which is sufficient for expansion of oil. The entire space is hermatically sealed against the atmosphere. A slight glass is provided to indicate the top oil level. One red ball will be visible through the slight glass. After delivery of the bushings, it should be checked whether the red ball is at the centre or not when the bushing is vertically placed. If the red ball is displayed from the centre, the bushing is defective and the same shall be reported to the supplier or manufacturer immediately. (iii) Bushing for 132 KV and above are equipped with a measuring tap at the bottom portion. It is used or checking the capacitance and power factor with the flange grounded. It can be used in conjunction with a special plug for measuring the voltage or for control purpose during operation. (iv) The bushings are suitable for vertical or inclined installations : Vm 73 KV : 600 to vertical plane. Vm 100 KV : 30o to vertical plane. When Vm is the highest system voltage. Bushings are fitted in inclined position in order to maintain phase to phase clearance required for the voltage system without increasing appreciably the tank size. (v) All bushings shall be provided with suitable shoulderless terminals of approved type and size and shall be suitable for bimetallic connection for terminal connectors. (vi) The insulation class of the bushings shall be according to voltage classes for which they are used. The insulation class of the high voltage neutral bushing shall be properly co-ordinated with the insulation class of the neutral of high voltage winding. Each bushing shall be so co-ordinated with transformer insulation that all flash overs will occur outside the tank. This is because of the fact that a damaged bushing can be easily replaced by a spare one but flashover inside tank will involve the risk of fire in the oil and entire transformer may be burnt into ashes. (vii) Special adjustable arching horns may also be provided for the bushings as per IS-371/1966, I.E.C. Publication No. 71A. This is very simple to look at, so it is generally neglected by site-Engineers. But arcing horns has tremendous importance and practical utility for the safety of the bushing as well as to reduce the length of the bushing. Without arcing horns, the length of the bushing would have been very high in order to provide sufficient creapage distance against any unanticipated high surge to bear with. The purchaser should ask the supplier to provide the guaranted withstand voltage for the arching horns and also furnish a calibration curve with different settings of the coordination gap to the purchaser to decide the actual gap setting or as recommended by the manufacturer or supplier.

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Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. The bushing shall be suitable for normally polluted and heavily polluted atmosphere as well as under different weather conditions. In this respect both total and protected creapage distances are very important. To avoid failure by tracking following minimum creapage distances are specified. Indoor insulators : 16 to 18 mm/KV Outdoor moderately polluted : 18 to 22 mm/KV Outdoor hea vily polluted : 25 to 30 mm/KV However, for normally polluted atmosphere minimum total creapage distance OK in mm can be found out from the equation approximately as 23 Lk = ——— Vm mm. 1.5 Protected creapage distance at an angle of : 45o = 61% 900 = 43% For heavily polluted atmosphere the minimum creepage distance Lks in me can be found out as— Lks = 23 x Vm mm Protected creepage distance at an angle of : 45o = 74% 90o = 55% So as a thumb rule, total creepage distance shall not be less than 23 mm/KV for heavily polluted atmosphere. 11. Insulation Resistance Value (I.R.Value) : If an insulation is placed between two conductors and D.C. voltage (Vide) is applied and a current Idc flows, then insulation resistance is the ratio of Vdc/Idc. It is measured in Meg. Ohm by Megger. As per I.A. 1886/1961, I.R. value of a transformer can be estimated by the following formula :I.R. Value in Meg. Ohm = 30 x KV / (XVA/f) = 7 Where f is the power frequently. This formula is now superseded as it gives low values on higher voltage ratings. C.B.I.P. has specified following. I.R. values at 20oC. for different voltage clauses. L-L voltage in KV Min. IR values in Meg. Ohm at 20oC (Tr. winding to ground)

Below 6.6KV upto 400 V

Above 6.6 KV upto 11KV

25 KV

400

600

670

33 KV 138 KV 230 KV

890

3920

6200

At high temperature I.R. values will be reduced. The correction factors at different temperature have also been specified by C.B.I.P. For every 10oC. temperature fise, the correction factor may be taken as 2 as very rough general rule. As for example, C.F. at 30oC. is 1.8. So 11 KV winding at 30oC should have a minimum I.R. value of 600/1.8 - 333 Meg. Ohms. Lighting Arrestor is the lowest insulated equipment and transformer is the next higher insulated equipment in any power system, Cost of transformer increases with its insulation level. Depending on technique of surge divertors, insulation level. Depending on technique of surge divertors, insulation level of a t ra transformer can be reduced with consequent reduction in overall cost which can further be reduced with grading of insulation at the neutral end of the transformers aided by suitable protection arrangement depending on system earthing condition. Extent of reduction in insulation level vis-a-vis cost reduction depends on various factors like voltage stress in the windings, axial and radial strength of meg. field etc. However, insulation level of high voltage power transformers shall be verified through impulse testing and chopped wave testing, but distribution transformers shall be verified by double voltage double frequency tests during purchase. So it is very important to use matching L.A.S. with transformers during its operation and maintenance.

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Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. 12. Absorption Factor OR Polarisation Index Value (P.I. Value) : The healthy condition of a transformer can only be ascertained by detailed testing of its oil qualities vis-a-vis measurement of I.R. values at site. As the number of transformers are increasing day by day it is troublesome, and time taking process to test the oil of all the transformers before taking decision for reconditioning and / or replacement of entire oil which is not only costly but also execution of reconditioning / replacement of entire oil within limited time of 2/3 months in a year due to opportunity of availing shut down, becomes practically impossible and impractical. So many transformers are getting burnt with the consequence of heavy financial burden to S.E.B.s. for replacement, besides, revenue loss due to power interruption and public dis-satisfaction. In order to cut short the process and to take quick decision for reconditioning and / or replacement of oil for those transformers only which are in deteriorated condition, we have recently purchased Motorised Megger costing about 1-5 lakhs, for measurement of Absorption Factor or Polarisation Index Value (PI value) to ascertain the degree to which moisture has been absorbed by the insulation of winding of the transformers i.e. how much humid the insulation of the transformer is. The P.I. value can be defined as follows :The ratio of value of insulation resistance as read from Megger scale at 60 seconds and 15 seconds after the test D.C. voltage has been applied to the windings of the transformers i.e. (I.R. value) 60/(Ir-value) 15 is called the Absorption Factor or Polarisation Index value (PI-value) of the insulation of the transformer for that winding. The P.I. value of dry insulation may be high as 1.5 to 2 and upwards, while damp insulation will have a P.I. value close to 1. So from the measurement of PI value Site-Engineers can take decision whether detailed oil testing will be required and / or whether the transformer will be allowed to remain in se service or shall be withdrawn immediately for improvement of its condition to avoid pre-matured death. 13. Tap Changer : There are three types of tap changer which are used in transformers depending on their service viz. (a) Off Circuit Tap Changer, (b) Of-load Tap changer, (c) On-load Tap Changer (OLTC). In Off-circuit tap changer transformer is disconnected from the circuit from both the sides during process of tap changing of-load tap changer transformer may remain energised on no-load and tap changing is done on secondary side making the load off. In OLTC tap changing operation is carried out when the transformer is delivering the load. Medium voltage classes distribution transformers and Traction transformers use either off-circuit or Off-load tap changer depending on circumstances. Below 132 KV system, tap changes are used in low voltage side but in 132 KV and above Tap changer are used in high voltage side considering economy. OLTC is of two types viz. Reactance Type (C.T.R) and Resistance Ttype (Bidirectional) explained later. In C.T.R. type power flow is limited to 70% in reverse direction but in later 100% power flow can be maintained in both direction. 14. Preservation of Oil inside Transformers : (i) Significance of I.R. Values : Quality deterioration of oil inside a transformer in service is due to high temperature, oxidation with air and having high effinity of the oil to absorb moisture during the process of breathing with the consequent effect of poor I.R. values leading to failure of transformers. Maintaining required I.R. values of transformers is similar to maintain percentage of Blood sugar (80% to 120%) in human body to avoid possibility of prematured normal death. A man without having required percentage of blood sugar will not die but will function lime a normal health but lot of medicine will be required for his recovery from any complicated diseases and / or ultimate death. So also a transformer having poor I.R. values, will supply power as usual but having the risk of getting burnt during a sudden shock due to abnormal faults which is quite unpredictable and unforeseen. The financial constraints and earliest opportunity of availing shut down etc. compel us to take the risk of keeping the transformer in service and ultimately allow it to burn. (ii) Conservators : In earlier stages when oil of 'Paraffinic base' was used the problem of oil contamination and quick reduction of I.R. value was not so acute and use of conservator having

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Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. volume nearly 1/13 of the main tank oil volume was sufficient to restrict the contamination of hot oil with surrounding in the process of breathing and was more or less sufficient and satisfactory, besides accommodation of expanded oil due to heat. Due to use of 'Asphaltic' oil, it was felt necessary to retard the quick deterioration of oil by avoiding direct contact of atmospheric air with the oil. To improve the performance Nitrogen sealing system of conservators have been developed when an inert atmosphere of Nitrogen is created over the oil inside conservators. Moisture is also excluded because of avoidance of beating directly from atmosphere. The Nitrogen gas supplied from a cylinder is slowly consumed when the temperature excursion is too wide. But under normal variation of oil temperature excursion is too wide. But under normal variation of oil temperature there will be no consumption of Nitrogen gas but during life period of 25 years leaking of gas can not be avoided and creates a problem for replacement or refilling of Nitrogen gas at site. In further development of Diaphragm type conservators, a rubber diaphragm is employed to create a partition between oil and outside air. (iii) Thermo Syphon System : In thermo syphon system, a part of oil is circulated through an adorbent sieve of Alumina or specially made Silicagel (In Russian Transformers) for automatic reconditioning of oil. The oil circulation is achieved by means of Themo Syphon Action. (iv) Use of Bidirectional OLTC : During tap changing operation, a part of the winding between two successive tapes is short circuited and the short circuit current is limited to safe value by a centre tapped reactor in a C.T.R. type OLTC housed in the main tank earlier. The current maxima lags behind the voltage maxima by a quarter of a cycle causing high possibility of arching between fixed and moving contacts specially during transition period. Due to such heavy arcing, the life of contacts become limited, oil is deteriorated / contaminated quickly leading to failure of OLTC or transformer as a whole. So CTR type OLTC has been replaced by Bidirectional OLTC developed by Dr. Jansen in West Germany where short circuit current is limited by constantly rated resistors for all temperature and current ranges. Current maxima and voltage maxima accruing at the same instant reduces the arcing possibility to a great extent and oil deterioration becomes retarded, Moreover OLTC and its Diverter switch is hour houred below the tank and the oil of this tank is kept entirely separated from that of the main tank thus main tank oil is preserved from contamination / deterioration by the arcing action of OLTC. The conservator is divided into two compartments, bigger one is connected with the main tank through pipe, Buchholtz Relay and Breather and smaller one is connected with OLTC tank by oil Surge Relay and a separate Breather. Replacement of only OLTC tank oil becomes less costly and easier and time savings. (v) Atmoseal System : The most recent development for preservation of oil inside a transformer without atmospheric contact at all is the 'Atmoseal System' where an air bag made of hot oil resistant Nitrile rubber called 'Pronal Air Bag' is mounted inside the conservator with its opening connected to dehydrating Breather through pipe. The bag inflates or defaults as the oil in the conservator expands or contracts due to temperature variation to and from the main tank thus prevents any atmospheric contamination maxing with the oil at all. The system requires little maintenance and the oil is preserved to its original standards or a long time because of no direct contact with air. Preservation of oil outside Transformer : If the oil received in drums is not likely to be used immediately the drums should be stored in a covered space where temperature variation is minimum, If it is necessary to store the drums outside, adequate protection must be provided. Drums should not be stored standing on end but to be stored horizontally with bung at 45o downwards. 15. Bucholtz Relay : It is a gas actuated Relay and is connected in the oil pipe work between transformer tank and conservator. The shut of valve is connected between the conservator and the Buchholtz Relay. The relay is mounted in the pipe work with arow on the housing of the Relay pointing towards the conservator at an angle of 3o to 7o or 10o to the horizontal plane. Any gas formed in the main tank oil will tilt the float to cloase the Alarm Circuit first and then Trip circuit

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Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. to trip the transformer. This is a slow acting relay having minimum operating time of 0.1 second and average time of 0.2 second. Such a slow acting relay is unsatisfactory no doubt but is excellent to bring the notice of incipient or internal fault of transformer. Once there is operation of the relay. the accumulated gas shall be collected at the stop-lock and shall be analysed to diagnose the fault. From the rate of increase of gas an estimate can be made of the severity and continuance of the fault. First it shall be tested whether the gas is inflammable or not. (a) If so, a definite diagnosis can be made from the colour of the gas as follows : Colour Cause

White Destroyed paper

Yellow Damaged wood

Black or Gray Dissociated oil

(b) Oil Surge Relay : In bidirectional OLTC, Tap changer and its diverter tank is housed in a separate chamber completely separated from main tank oil. though immersed in the main tank. Conservator is divided into two parts. Bigger part is connected with main tank and Bucoholtz Relay with a Breather and the smaller part is connected with oil surge relay and a breather. Any fault is the tap changer and formation of gas, oil will be forced to enter the relay to operate. (c) Magnetic Oil Gauge (M.O.C.) : This is a dial reading gauge mounted directly on the conservator to give continuous oil level indication. It is normally mounted on the conservator end-cover (detachable) at the inclination 15o to the vertical so that it will be readable from ground. This is supplied with low oil level alarm contacts. This oil gauge is electrically connected to the terminal box and then to Marshalling Box. The dial of the indicator is calibrated to give level of the oil as a function of the conservator capacity. A mercury which is provided so that when oil level falls below a specific level an alarm is sounded. The instrument is a float type and the movement of the float is transmitted to the pointer by means of a magnet hence the name M.O.G. (d) Temperature Indicators : Oil temperature and winding temperature indicators (O.T.I. & W.T.I.) provide local indication of top oil and winding hot spot temperature respectively, are fitted in the junction box or Marshalling box. The thermo meter bulb is connected by capillary tubing to the local indicator. The bulbs are enclosed in oil filled pockets which are either welded or screwed on the transformer cover in the hottest oil region. In O.T.I., the expansion of liquid in the bulb is transmitted through capillary tube to indicating instrument for indication of top oil temperature. W.T.I. may be either with built in heating elements or with separate heater bulb. In case of former the pocket or the bellow has a heating coil around it which is fed by a C.T. (secondary) provided on one of the transformer line terminals of H.V., L.V., T.V. windings, so that any change in the load is reflected in the heating of the pocket / below of W.T.I. The C.T. secondary leads are connected to the instruments in terminal / marshalling box. In case of later a separate pocket is provided on transformer cover for housing the heater bulb (with capillary) and two terminal W.T.I., C.t. secondary leads are connected to the terminal inside the tank and connections from pocket terminals to heater bulb are made internally in the pocket. This pocket is air filled. Instruments in both the cases are housed in terminal / marshalling box. It is to be ensured that the transformer oil is filled in the various thermo-meter pockets on cover before commissioning of transformer. The dial type thermometer is also provided with mercury switches for an Alarm and Trip circuit operation in the event of executive temperature raise and W.T.I. also controls operation of cooling fans, oil pump motors at certain present temperatures. A potentio meter device or a digital method is also provided for remote temperature indication. The signalling contacts of O.T.I. are generally set to operate at the following temperatures or at a slightly lower values depending on condition of the transformer.

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Protection System

O.T.I. W.T.I.

Cooling System

Alarm On

Trip Off

Fan On

Off

Pump On Off

85oC 100oC

95oC 100oC

85oC

60oC

90oC

65oC

(e) Fault Current : Fault current at different system voltages are furnished below :Line to line Nominal system voltage in KV Steady state Fault Current KA (R.M.S.)

18.

19.

(i) (a)

11

33

132

220

400

13.1

25

30

40

50/60

So Transformers should be protected against such shock and should be tripped by the circuit Breakers within 3 cycles or now a days 2-21/2 cycles. Oil Testing : In power Transformers decision for reconditing has to be taken if the I.R. value is poor, IP-valve is not satisfactory as well as rigorous oil testing results are not also satisfactory. But in large number off 11/.415 KV transformers all such testing will not be practicable, economical, and a continuous time taking process. So the following simple test may be conducted to ascertain the healthy condition of the transformer besides IR value measurement. Crackle Test for 11/0.415 KV transformer : In 11/0/415 KV distribution transformers all such detailed processes may not be economic. So a simple test called "Crackle Test" may be done as a quality checking of transformer oil vis-a-vis insulation resistance. Oil sample from the transformer may be collected in a pot. A metal rod 1/2" (12.7mm) dia heated to a dull redness is dipped into the sample of oil and when stirring, there will be no crackle sound. One end of piece of a stool tube of about 1.2" dia shall be closed and closed and is heated at dull redness. The heated and of the tube shall all be plunged into the oil sample taken in a container with the ear closed to the open of the tube. If a sharp crackle sound is heared, it indicates moisture in the oil. Above tests are very simple to carry out and if presence of moisture is indicated in the test, oil of the transformer shall be replaced, otherwise the same will be burnt. Distribution Wing should follow this test to reduce the failure of such transformers which is alarming in numbers. Causes of failure of transformers : Prematured death of transformer within its life period of 25 years shall be considered as a crime to the society. The reasons of failure of transformers may be due to (i) Internal Factors (ii) External Factors, which are discussed below in short :Internal Factors : High Temperature : Internal factors responsible for the failure of transformers are due to bad and improper design. Con siderable amount of power fed to the primary circuit of a transformer is lost as core loss or iron loss and cu-loss or load loss, the former maintains the magnetic circuit and this latter is converted into thermal power or heat and needs to be effectively dessipated otherwise there will be high temperature rise and should be limited within 75 to 80oC. The losses are undesirable no doubt but unavoidable, as such shall be dealt properly for economic and effective design of transformers, In the design and operation of a transformer, two losses are considered separately but they should be considered jointly in respect of thermal power generated hence rise of temperature. So many transformers are failing due to high temperature.

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Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. (b) Design for over Load capacity : Cost of trans fomor can be adjusted appreciably with that allocation of two losses viz. Core and Cu-losses and ratio of Cu-loss to Core loss, by choice of core material, percentage reartance, Core section and section of copper conductors. moreover, loss ratio influences the over load capacity of a-transformer. It is very important design parameter specially for distribution transformer where over loading is practically unavoidable. power transformer shall be designed as per specified over load schedule but distribution transformer shall be designed to withstand 110% continuous loading with better core materials having better energy saving potential. (c) Dry Transformers and Amorphous Metal Core Transformers : Dry Transformers : In order to avoid oil hazards and routine monitoring of large number of distribution transformers installed over wide ranges of remote places dry type distribution transformer have been developed but the design is still in its limitior within medium voltage class of 11KV and having limited output rating of 1000KVA or slightly more. As the rating of transformer increases with the increase of voltage classes, problem of heat dissipation has yet to be solved in this design. Moreover, minor repairing is not possible at site. Amorphos Metal Core Transformer : Amorphos Metal Core transformer for distribution purpose is increasing at rapid rate in USA due to excellent energy saving potential. Core loss is about 30-50% that of best C.R.G.O. core and cu-loss is also reduced, hence temperature rise is very much reduced. But manufacturing cost is 25-30% that of best C.R.G.O. core and cu-loss is also reduced, hence temperature rise is very much reduced. But manufacturing cost is 25-30% higher than C.R.G.O. steel core transformer. (ii) External Factors : External factors responsible for the failure of transformers include (a) Over Loading (b) Inadequate protection (c) Improper maintenance (d) Social problems. (a) Over Loading : While giving a new connection, it is essential that the loads of existing consumers on the transformer and the diversity factor are taken into consideration. The power tariff for Tube-wells is generally based on a flat rate per H.P. of motor capacity. Many a time, the actual motor capacity is higher then the name plate affixed to the motor. In transformers supplying mixed loads such as lightning loads all the 3-phase are to be balanced. In addition, the problem of illegal use of electrically by 'Hooking' is now a social problem. (b) Inadequate protection : This is probably the single largest reason responsible for failure of transformers. In actual practice the protection devices provided are either inadequate or totally absent. Generally fuses are used in H.T. and L.T. side of the transformer instead of circuit-breakers. Moreover, the fuses are seldom or proper rating, thus providing no current protection to the transformers. Similarly impulse voltage protection by installation of L.As. in the system is not adequate. The introduction of static devices and more recently micro processor have made the protection system more full proof. (c) Improper Maintenance : It is commonly accepted that once the distribution transformer has been installed no maintenance is downs. The loccasion of the transformer is remote area further adds to the problem. Due to this oil quality determinators regularly. The oxidation and consequent sludge for oil affect the life of the transformer as proper care is hardly taken. (d) Social Problems : Besides, there are other social problems which result in failure of transformers, such as theft of transformer oil and metal parts, short circuit of overhead L. T. distribution networks that aggravate during rain and storm.

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Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. 20. Minimising Failure Rate : The new technology introduced so far have their respective limiteions, so with our available processors we must develop, mens how to improve the conventional design so that failure rate of distribution transformers can be minimised. Some SEBs have adopted one technique with success of reducing the failure rate from 10% to 2% which is explained below in nut shell. Distribution transformers purchased from different manufacturers shall be demarcated separately by different colour codes. Failure are of each manufacturer during a definite period of time (say last 4 years) shall be determined. Unit resultant cost of failure and repair shall be added directly to purchase cost while evaluating the tender bids which will reward the most reliable suppliers and give initiative form improvement. In general, it may be said that use of better CRGO steel as core materials, lower temperature rise of top oil over ambient, over fluxing upto 12.5% flux density in the range of 1.55 Wb/m2 suitable increasing the no. of steps of core with increase of KVA rating, properly specified HV/LV winding materials can improve the design of such transformers and minimise the failure rate to a great extent. In case of Power Transformer, manufacturing shall be strictly as per specification with proper importance to Loss-Capitalisation and testing before accepting the transformer. Regarding maintenance, "Yellow Card" prescribed by W.B.S.E.B. shall be maintained where history of the transformer shall recorded and Site Engineer should carefully note the gradual change of different characteristics of the transformer and should take corrective measures as quickly as possible. Increasing tendency of T emperature rise shall be considered as warning towards danger. 21. Insulation Level : (i) The dielectric strength of winding insulation and that of the bushing shall conform to the value given in IS-2026/1962 (as amended upto date) or IEC-Publication for rated system voltage 11, 33, 25, 132, 220, 400KV, the respective winding of the transformer shall have following insulation levels on the basis of 1.2/50 cicrosecond impulse voltage test.

System voltage (KV)

Impulse Test Voltage (KV Peak)

11 33 25 132 220 400

75 170 250 550/650 950/1050 1300/1425

High voltage winding of the transformer shall have graded insulation. The insulation class of the neutral and of the H.V.Winding shall be graded to short time power frequency withstand voltage of 38 KV (r.m.s.) The L.V. neutrals shall be graded as per voltage class of the neutral but not less than respective line voltages in case of 11 KV or lower voltages. (ii) The cost of a transformer increases with the insulation level. Other things being equal, substantial decrease in the cost of transformers can be brought about by reducing the insulation level permitted by the progress with technique of surge divertors, Depending on the system earthing conditions i.e. for solidly earthed system, cost can be reduced (more for higher voltages) by grading of insulation at the neutral end.

WBSEBEA - 72

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. 22. Power Frequency withstand Voltage : (i) Power frequency withstand voltage in K.V. (r.m.s.) for different system voltages may be specified as follows : System Voltage (KV)

Power frequency withstand voltage (K.V. R].M.S.)

220 132 66 33 11

395 230 140 70 28

(ii) The necessity and importance of fixing impulse level and power frequency withstand voltage for different voltage classes of transformer windings is very important for the reasons that over voltages encountered in electrical networks may be divided according to their origin, into two main classes : (a) External over voltage due to lighting and associated phenomenon. (b) Internal over voltages, due to sudden alteration in the internal circuits of the network itself. (iii) (a) in order to withstand external over voltage of high frequencies, the transformer windings shall be manufactured as per specified insulation levels and to be ascertained through testing. As higher insulation levels higher costs, minimum safe insulation levels are to be determined from system studies and to be specified in the specification to comply with. (b) Internal over voltage may be divided into two principal classes viz (1) Dynamic over voltages at system frequency due to unsymetrical faults, sudden loss of loads of turboalternator or a transformer connected to the end of a transmission line etc. (2) Transient over voltages at medium frequency due to rupturing of capacitive currents by restoring circuit breakers, or due to dead earthing of one of two phases. The transients of these nature may be 1.1 to 3.5 times the normal system voltages and usual range may be taken approximately as 1.7 to 2.2 In order to withstand such over voltages of power frequency and medium frequency transformer windings shall conform to the power frequency withstand voltages specified above different voltage classes and to be verified through testing. 23. Short Circuit Level : (i) Short Circuit level of different system voltages shall be as follows :

400 KV 220 KV 132 KV 33 MV 25 KV (Single Phase) 11 KV

-

25,000 MVA or 20,000 MVA 15,000 MVA or 10,000 MVA 10,000 MVA or 5,000 MVA 1,000 MVA or 750 MVA 750 MVA

-

250 MVA.

WBSEBEA - 73

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. (ii) Dont's 1. Do Not energise without through investigation of the transformer, whenever any Alarm or Protection is operated. 2.

Do not re-energise the transformer unless Buchhloz's gas is analysed.

3.

Do not re-energise the transformer without conducting all pre-commission checks. The results must be comparable with results at works.

4.

Do not handle the off circuit tap switch, when the transformer is energised.

5.

Do not energise the transformer unless the off-circuit tap switch is in locked position.

6.

Do not leave off - circuit tap switch handle unlocked.

7.

Do not over load the transformer other than specified limits as per ISS - 6600.

8.

Do not leave the tertiary terminals unprotected out side the tank, connect them to tertiary lightening arrestors protection scheme, when connected to load.

9.

Do not allow WTI/OTI temperature to exceed 75oC during dry out of transformer and filter machine temperature beyond 80oC. As we are now using Aspheltic or Naptha Base Oil, it is better to maintain transformer oil temperature at 60oC and filter machine temperature at 70oC to avoid burning of oil.

10.

Do not parallel the transformer which do not fulfil the condition for paralleling.'

11.

Do not use low capacity lifting jack on transformer for jacking.

12.

Do not move the transformer with bushings mounted.

13.

Do not change the settings of WTI and OTI alarms and trip frequently. The settings should be done as per site conditions.

14.

Do not leave red pointer behind the black pointer in WTI and OTI.

15.

Do not meddle with the protection circuits.

16.

Do not leave any connection loose.

17.

Do not allow conservator oil level to fall below 1/4 level.

18.

Do not allow the level to fall in the bushings. It must immediately be topped up.

19.

Do not leave the marshalling box door open, they must be locked.

20.

Do not switch off heater in the marshalling box except in summer.

21.

Do not allow dirt and deposits on the bushings. They should be periodically cleaned.

22.

Do not allow un-authorised entry near the transformer.

23.

Do not leave leader un-locked when the transformer is 'ON', in service, in case it is provided.

24.

Do not change the sequence of valve opening for taking stand-by pump and motor into circuit.

25.

Do not switch on water pump unless the oil pump is switched on.

26.

Do not allow water pressure more than the oil pressure in differential pressure gauge.

27.

Do not mix the oil unless conforms fully to ISS-335.

28.

Do not allow inferior oil to continue in transformer. The oil should be immediately processed and to be used only when it conforms to ISS-355.

29.

Do not continue with pink silicajel, it should immediately be changed or regenerated.

30.

Do not leave secondary terminals open of an un-loaded C.T.

31.

Do not commission the transformer in case iI.R. values are not satisfactory.

32.

Do not continue to run the transformer with relief vent diaphragm broken or crack.

33.

Do not store transformer for long after reaching site. It must be created and commission at the earliest.

34.

Do not keep the transformer gas filled at site for long period.

WBSEBEA - 74

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TRANSFORMER TESTING While discussing test on tranformer it is needless to say these tests are normaly done for the power transformer. As the distribution transformers are manufactured in a lot and very low in costs in comparison to the power transformer all these tests are normally not performed on distribution transformer. Detail transformer tests are done mainly at factory and at site during its first installation and commissioning. (i) Factory Tests : (A) Routine tests (a) Winding resistance (b) Vector group analysis (c) Open circuit / No load current and loss (d) Load current and loss (e) Insulation resistance between HV-E, LV-E & HV-LV (f) Dielactric tests of insulation, bushings etc (g) Tests of protecting equipments (h) Tap changer (i) Test of cooling circuit. (B) Tyre tests (a) Temperature rise test (b) Lighting impulse test (c) Switching Impulse test (d) Partial discharge test. (C) Special test (a) Zero sequence impedence test (b) Short circuit test (c) Measurement of hermonic of no load current (d) Measurement of noise. (e) Cooling power loss test (f) Main tank vaccum test (g) Oil leakage test. At site before testing of the transformer and its commissioning following things are checked. (i) Oil level in bushing, main conservation tank and diverter tank. (ii)Condition of explosion vent, silicagel breather (iii)Neutral and body earthling of the transformer.(iv) Leakage of oil from any part of the transformer (v)Operation of tap changer (vi) Trapped air release (viii) Setting of relays (viii) Matching of vector group (ix) Visual Test. Test performed at site : (i) Polarity test (ii) Ratio test (iii) Winding resistance and various tap position. (iv) Vector group analysis. (v) Insulation resistance. (vi)Tests of oil (vii)Tests of protective equipments like bucholz, PRD, OSR, winding and oil tamp indicator. (viii)Auto, manual and remote, local operation of tap changer and cooling arrangement (ix)Tests of relays and protechtion scheme (x) Tests of indication of annunciation scheme. One format of testing report which is normally used at WBSEB is enclosed. Technical & proceedural details of same important transformer testing are detailed below.

TABLE - II

Hours of ageing 100 164 200 300 400 500 600 700 800 900 1000

Neutralisation Value, mg KOH/g Total sludge, % by weight Reclaimed Recleimed oil with reclaimed Reclaimed oil with oil 0.5% DBPC Oil 3.3% DBPC 0.20 0.225 0.24 0.28 0.30 0.33 0.36 0.39 0.42 0.45 0.48

0.035 0.04 0.045 0.050 0.070 0.090 0.11 0.33 0.39 0.41 0.45

WBSEBEA - 75

0.04 0.06 0.07 0.10 0.12 0.15 0.18 0.22 0.26 0.29 0.32

0.004 0.005 0.005 0.006 0.007 0.008 0.015 0.012 0.013 0.15 0.16

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. (1) Measurement of Polarity, Ratio and Vactor group. Ratio test is conducted to ensure correctness of turns ratio between different wining on each tapping. Tolerance allowed for ratio is + 0.5% of the declared ratio or + 10% of the percentage impedance voltage whichever is smaller. This is done by Transformer Thrns Ratio Meter (TTR). Basic principle of working of a TTR meter is to compare the voltage obtained in the secondary of a transformer under test to that of a standard transformer whose ratio is known the fig. in Annex-III shows the basic connection. The primaries of the transformer under test and the standard transformer are energised from a low voltage source. The secondaries are connected in opposition and a null detector is inserted in between the secondaries. When the ratio of the two transformers are identical no curent flows through the null detector. The ratio of the standard transformer is recoreded as the ratio of the transfomer under test. This is of course an elementary circuit, in the actual meters the comparison is done in the different manner which varies with manufacturer of bridge. For a three phase transformer it is usual to carry out a vector relationship test in which one of the high voltage and low voltage line terminals are joined together for start-star and star-delta transformers and three phase 400 V supply is connected across high voltage line terminals. Voltage between terminals IUI, IVI, IWT & 3UI, 3VI, 3WI like IUI-3VI, IVI-3VI, IVI-3WI, IWI3WI, IWI-3VI) II-3VI. Vector relationship for any other group and be checked in a similar manner. Though the ratio and vector group tests have been carried out at factory and obtained at site, the test is still done as a confirmatery test. This also indicates whether tap switches are properly connected and no damage has been done during transportation. This also help to build up a data with a particular bridge (measuring instrument) so that the result can be compared in future by taking reading by the same brodge. 2. Measurement of winding resistance : The reading of C.C. winding resistance at all taps of each winding is taken with help of either a wheastone bridge or by Kelvin's double bridge. While taking measurement care is taken that inductive effect of winding is eleminated. As resistances value is dependent on temperature, it is imperative that temperature of winding must be stable during measurement and the temperature must also be recorded. When wheatstone bridge is employed the lead resistance is measured and subtracted to compute the winding resistance. When the winding resistance is low it is better to use kelvin's double bridge as these are more accurate. After measuring the winding resistance the values obtained are compared with those obtained during factory test. The comformity of result prove proper connection of tap switch, bushing terminals etc. This also provide a buse data for future reference. Normally at the manufacturer's work resistance, values for a tapped winding are measured only in three tap but at site it is measured at all taps to check connection of tapping. It would be better if a clause is incorporated in P.O. so that resistance at all taps is also measured to get our idea during site testing. 3. Low Voltage Magnetising curent measurement : This low voltage test is conducted by supplying 3 phase 400 volt supply across each winding (primary, secondary, tertiary where (applicable) and keeping other windings open circuited. It is important that the earth connection to neutral is removed during measurement otherwise misguiding results would be obtained. Reading on meter low range (normal few milliamps). Act. ampere is taken and receorded along with supply voltage. Normall one reading on principal tap is taken for a tapped winding transformer. Identical results of factory and site confirm intactness of core & winding after transportation. This test also supplies valueable base data, which is required if a transformer goes defective, for comparison. Faults involving turns of winding can easily be mentioned with the help of the simple test. Also it has been observed that at the time of testing a transformer during abnormality, the current measured in each phase of winding by applying single phase low voltage give much more unbalanced currents in defective phase than the simultenous measurement of current by applying 3 phase voltages. The comparison of data in healthy condition and faulty condition help in locating and

WBSEBEA - 76

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. pinpointing the trouble spts. As such this measurement is taken then carrying out core balance (or magnetic balance) test which is described below. Sometime the factory test result indicate measurement) only. It is preferred that magnetising current at low voltage is also measured during factory test so that comparison of data after measurement at site is possible. 4. MAGNETIC BALANCE TEST : This test is not covered in I.S. but it gives valuable information regarding healthyness of core and winding of a transformer. It is done by applying single phase voltage between phase and nutral of a start connected winding and measuring voltages induced in other two phases of some winding. This single phase current drawn by the winding also recorded asmentioned earlier. The following points may be noted : (i) Transformer nutral should be disconnected from ground. (ii) No winding terminal should be grounded otherwise results would be erratic. (iii) Zero voltage or very negligible voltage induced in any of the other two phases should be investgiated. (iv) The test is conducted on principal tap. (v) When the transformer core is a five limbed one, sometime the results are confusing as the single phase flux finds another path through the auxiliary limb. The results are recorded in tabular form shown below : Tap Voltage Recorded r-y y-b b-r pos R-N Y-N B-N or r-n y-n b-n ...............( )............................................................................................................................ ...................................................( ) ........................................................................................... ......................................................................( ) ...................................................................... The dashed figure shows the winding to which voltage is applied. The single phase current is recorded inside the bracket. It may pointed out that at the time of recording the current, voltmeter should not be left connected to any winding at the current draw of the voltmeter will affect the single phase magnetising current. Normally this test is not done at work as it is not mentioned in the I.S. and also we were not doing it (it is not mentioned in test report format). But it has been observed that in base datasnaps in defecting troubles in winding and core, if a transformer be defective. It is also preferred that while placing order this test clause is included in the purchase order so that the test is conducted at factory also. There is still some controversy regarding the result and aim of this test. It has been seen that with mitred core, the result in often affected by temperature, as the joints expands or contracts the flux linkage pattern changes. Still then wide variation of inducced voltage indicated by magnetic balance test on a defective transformer clearly shows trouble spots in conjunction with other test result. As such this test hasnow been included as a routing for site testing. 5. MEASUREMENT OF I.R. VALUES. The I.S. specification says insulation of resistance of each winding, in turn, to all other windings, core and frame or tank connected together and to earth shall be measured and recorded. The oil/air temperature shall be measured and recorded immediately prior to the test. It is also castomary to take reading of each winding to earth (with other floating) and between windings. In with a 1000 V/ 2500V/5000V megger and the result is compared with those obtained during factory test. The following points should be noted : (i) The transformer tank must be connected to earth. (ii) The lead wire of the megger should run independly and should not touch any other object. The lead should have no joints. (iii) The readings of infinity should be checked with lead connected and rotating the hndle of the instruments.

WBSEBEA - 77

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. (iv) It is better to take the reading after 1 min. and hence motor driven megger is preferable. (v) The external surface of the bushings should be cleaned with cotton cloth prior to taking reading. There is no limit prescribed in I.S. in regard to insulation resistance and the value obtained during factory test is the guiding factor. The reading obtained for transformer vary with size and voltage and with temperature and humidity. Insulation resistance when correlated with temperature and referred back to previous test. Large or progressive vairation of insulation resistance from initial value indicate detoriation of the insulation and presence of moisture either in the winding insulation or the oil or both. It should be noted, however, that insulation resistance test is not of itself a guarantee against possible failure in service and knowledge of the conditions and history of transformer are necessary before placing reliance on any given single set of readings. Still this test is of prime importance for building base data as noted earlier and variation from earlier record require investigation and corrective action. 6. Testing of transformer oil : Transformer oil testing is gaining importance day by day as experience has indicated with oil being a vital insulating medium, its condition need to be valuated in strict manner. Previously we used to measure the BDV value (Dielectric strangth) of oil only. Though BDV is the basic parameter and indicate presence of contaminating agents like moisture, fibrous materials etc. Other properties like resistivity, dielectric dissipation factor (Tan delta). Master containter facial tension must be measured prior to commissioning of a transformer. In fact water content of the oil should be measured periodically during drying out of the transformer at site by filtration of oil and the process of filtration should be stopped only when the water content value is within the limit prescribed in IS 1866. This specification has included one list recently which is applicable for transformer before its energisation at site (Annex-V). The BDV of oil should be tested at site itself and the test facility for specific resistance, Tan Delta, acidity, interfacial tension are available at CTL. The instrumen of measuring water content is being procured by CTI and till the facility is available, should be done with help of outside agencies. Monitoring the condition of oil is gaining much importance due to the fact that paraffinic base insulating oil available indegently shown a faster rate of deteroration of electrical properties than of naphthenic base oils which were available for our use till early 70's. It is noticed that due to poor condition of oil, I.R. values of transformer goes down and may affect the life of the transformer leading to its failure. Compliance if test result to I.S. 1866 prior to charging and subsequency test result of the sample taken from the same transformer indicate necessity of taking correctiveness of that one should take in regard to this vital insulating medium. 7. SHORT CIRCUIT AND CHECKING STABILITY OF DIFFERENTIAL PRELOCATION. This test is conducted at site by applying three phase 400V supply to LV side before LV CTS' and short circuiting the H.V. phases after H.V. CT's. This is in effect creating a condition of through fault for a differential protection. Current in each phases flowing through the primary washing of the transformer and also the secondary currents in all circuits including the spill current through operation coil of differential relay are measured. The spill current through the operating oil should be negligible compared to current flowing through the bias coils of the differential relay. This proves that connection of C.T. circuits are healthy and as per standard. This test is normally done at principal tap. Differential protection of a transformer compares the current flowing in the primary and secondary windings of the transformer. In application of differential protection the following points need careful consideration :(a) Magnitude of currents : The currents on the two sides of a transformer differ in megnitude - they are in inverse ratio to the voltages on two sides, C.T's are scle 'c' so that the currents match in the secondaries to the extent possible and I.C.T's are employee to handle the mismatch still left

WBSEBEA - 78

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. as well as to pass rated current (IA/3A) through bias winding of the relay when the transformer is on 100% load. (b) Phase : In polyphase transormers the transformer winding connection results in a phase difference if currents in primary and secondary windings viz. for a star / delta transformer there will be either + 30o phase difference between primary and secondary current depending on the vactor group of the transformer. This is taken care of by connection of the C.T. secondaries and / or the I.C.T's (When employed) so that relay does not operate for load flow/external fault. (c) Transformer neutral connection : The CT secondary or / and ICT secondary connections are also influenced by Power Transformer Neutral connection to ground. As it means that a path is established for zero sequence current to flow in primary in case of an external fault (with no corresponding current outside the transformer secondary which may be delta connected), the zero so that differential relay does not operate for an external fault. This is done by connecting the secondary of the C T/. I.C.T. in de for star connected primary winding. A typical connection diagram for star / delta transformer is shown Annex - VI. As the scheme is quite eleborate and so many connections are involved in a particular fashion, the total scheme is checked during the stability checking of differential relay at site. 8. CHECKING OF STABILITY OF RESTRICTED EARTH FAULT RELAY. Restricted earth fault relay on start eonnected winding is checked by injecting 1 phase voltage to the neutral C.T. with three phase of H.V. winding shorted together and earthed after H.V. CT as shown below.

Of course in the above arrangement, the current driven through the transformer is not much but still a clear picture so as to correctness of connection of secondaries of the relay is obtained. For testing with higher values of current the transformer winding is by phase by a temporary jumper parnal a current injection set employed as shown below.

For a healthy connection the spill current through RF relay should be negligible compared to main or secondary currents. If restricted earth f ault is applied for winding connected in delta the stability of the relay is

WBSEBEA - 79

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. checked during short circuit test. 9. Checking of operation of circuit breaker (with isolator open) When all testing as well as miscalleneous checking have been completed tripping of circuit breaker is checked for operation of each protection. 10. COMMISSIONING : After completion of all aforsaid testing and checking, the transformer is energised at no load from H.V. also and kept energise for a period of 24-43 hrs. Temperature of oil and winding are monitored hourly so see the rise under no load condition. The humming of the transformer is noted for any abnormality. If no abnormality is observed transformer is sh ut down to cleck whether any gas has accumulated in the chamber of the Buchhelas' relay. Some trapped air may come out due to vibration and accumulate in the relay. After release of air, the transformer is reenergised and loaded gradually. (A) Other related testing on transformer oil Beside the regular tests of transformer oil i.e. (i) BDV test (ii) Resistivity test (iii) Acidity (iv) Moisture content (PPM) and (v) ( ) test some tests are done in a regular basis for condition monitoring of high voltage and cost power transformers. (i) DGA - Disolve gas Analysis (2) Furan Anglysis These tests are performed on the transfer oil but not to determine the quality of the DGA is a power fool tool to detect incipient fault in transformer & reactors. Furan analysis is done to assertain the condition of insulation and its nature degradation if any. DGA (A) Gasses found dissolved in transformer oil. (a) H2, CA4, C2H6 , C2H4 C2H2, CO2, CO, O2, N2 (B) Gasses are generated due to following reasons. (i) Arcing in oil - Huge amount of H2 & C2H2 (ii) Overheating of oil - CH4, C2H6 , C2H4 are formed in increasing order of sensitivity. C2H2 is favoured in very temperature. (iii) Partial discharge in oil - Iarge amount H2 and CH4 (iv) Cellulose overhealing - large quantities of CO & CO2. (C) Following are temps of the gas generation (i) CH4 > 120oC (ii) C2H6 > 120oC (iii) C2H4 > 150oC (iv) C2H2 > 700oC There are several methods of gas extraction & several methods for its analysis. Mainly an oil sample is first collected in sealed container and by heating and pumping different gas all the gasses are separated by single cycle, multicycle, head space or stripping procedure. The equipment for collecting and seperation of gas is mainly used is famally known as gas-cromatograph (GC). Methods of analysis are key gas, Ratio method and Trend analysis. Rate of rise & Acceptable lebel of dissolved gasses as per TEC 60699 Gas

Level

Rate of rise (ml/day)

Hydrogen CH4 C2H6 C2H4 C2H6 CO CO2

60-150 40-110 50-90 60-280 3-50 540-900 5100-13000

+R for toggling between Numeric & arrows keys mode.

6. MRI gives "Bad or Missing Command Interpreter" while resetting MRI.

1. User has removed COMMAND.COM line from CONFIG. SYS or given wrong PATH. 2. COMMAND.COM is corrupted or deleted.

1. Load Command.COM with exact path from : _promot. Ex. C:\DOS/COMMAND.COM. After getting DOS prompt change the contents CONFIG.SYS file as per default setting. 2. Take COMMAND.COM from other working MRI to PC and transfer the same into nonworkable MRI if FWCONFIG utility is supplied to the user otherwise send back to SML. 1. Press key marked "O" with "shift" key.

WBSEBEA - 237

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. TROUBLE SHOOTING OF ANALOGIC TYPE MRI Problem Symptoms Possible Reasons MRI seems in a Hang Mode [While using MRI S/W, user finds that MRI does not respond to any keyboard command and Display remains blank.] [MRI does not give Display but user feels that keyboard is working.]

Initial Operation before sending the MRI to SML

1. Key marked " " is pressed with "Shift" key.

1. Press key marked "O" with "shift" key.

2. MRI shows error to close the files.

1. Battery become low

1. Put MRI on charger after RESET of the MRI.

3. MRI is not reading Meter while read option is chosen (COMMSFAIL)

1. Meter may not be powered up 2. Cable breakage. 3. Cable is not properly connected. 4. Damaged Optical Head.

1. Check Meter is POWERE UP. 2. Check OPTO whether window of METER is clean or not. 3. Connect cables properly. 4. Try to communicate with other Meter to isolate whether problem lies with MRI/Cable/ with the Meter. 5. Change the cable for cable checking. 6. Make sure that the connect is inserted properly. Precautions : 1. Do not fold the cable with sharp bend near Meter connector. It will lead to breakage.

4. While Transferring / Receiving data-to / from computer. BCS lives COMMS FAIL.

1. Cable breakage (MRI-PC) 2. Cable is not properly connected. 3. Using Windows shell to execute SEMS_PAK. 4. Communication Setting at BCS side is not proper. 5. Loaded Memory resident program at BCS side Ex. Clock. Side kick.

5. In TERMINAL mode of MRI software, keys are not working as per notation. Example : 1. I have problem typing V1, V2 2. I have problem using delete. 3. Key to delete wrong character.

1. For capital letters use caps lock key (F key) at key board. 2. For deleting the character use shift and backsp.

WBSEBEA - 238

1. No memory resident programme should run on PC such as Side Kick, Clock etc. 2. Connect cables properly. 3. Keep the set-up Same & change the cable for cable checking. 4. Keep the set-up same a check communication with other PC. 5. Do not use DOS shell executing SEMS PAK. Precautions : 1. Do not fold the cable with sharp bend near meter connector.

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. Problem Symptoms

Possible Reasons

Initial Operation before sending the MRI to SML

6. Takes lot of time to come to DOS command line after selecting Quit uption of the main menu.

1. Updating diagnostic information. 2. Battery low does not allow it to proceed further after showing the halting signal.

1. Normal penavior. 2. Charge MRI and reset it.

7. MRI takes lot of time to declare COMMS-FAIL.

MRI is configured for MF summator while reading meter.

1. Configure MRI for Meter, Who reading meters.

8. Dump data is declared unsuccessful after transferring some data.

Multi-tasking operations have been performed on computer

1. Repeat without doing any the other then what is suggest by the BCS software.

Don't do : 1. Do not press Power/resume key, when MRI operation is going on. 2. Do not work with MRI, when low battery message has come on display. 3. Do not press any key at keyboard of MRI, when operations are going on. 4. Do not reset the Unit. RESET the MRI only when the battery low warning comes and says you to reset the MRI. 5. Do not go to the Setup Menu (2nd key with the key marked 'S') and do not change any parameters there. Do. 1. When Battery low message comes on MRI display, put MRI on charging and reset the unit. Operate only when it is charged. 2. Before using the MRI keep MRI on charger for 3rd hrs. to charge it fully. 3. When MRI is used in laboratory, then connect charger if possible. 4. We recommend MRI to be kept in POWEr OFF if the MRI is not used for very long time. 5. Press POWER/RESUME switch for 1-2 second to make to MRI in ON condition whenever the screen blanks which shown the SUSPEND mode of the MRI.

WBSEBEA - 239

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DISPLAY ITEMS FOR ABB ORDER NO. A ICMEC002201 WBSEB ORDER NO. P & SP - 11/2000 PC-11/240 P5 Sequence

ID

01 02 03 04 05 06 07

888 002 003 004 SYS 006 007

Normal Normal Normal Normal Normal Normal Normal

Complete LCD Test Present Date Present Time Total kWh Delivered System Power Factor Rate C Max kVA Q1 Demand Reset count

01 02 03 04 05 06 07 08 09

888 002 003 004 SYS 006 007 008 Pxx Pdr Pxx Pdr SYS PhA Phb PhC PhA Phb PhC SYS Ltd. 020

Alternate Alternate Alternate Alternate Alternate Alternate Alternate Alternate Alternate Alternate Alternate Alternate Alternate Alternate Alternate Alternate Alternate Alternate Alternate Alternate Alternate Alternate

Complete LCD Test Present Date Present Time Total kWh Delivered System Power Factor Rate C Max kVA Q1 Demand Reset Count Rate C Max kW Delivered PB Total kWh Delivered* PB Total kWh Delivered PB Rate C Max kVA Q1* PB Rate C Max kVA Q1 System VAs A Phase Voltage B Phase Voltage C Phase Voltage A Phase Current B Phase Current C Phase Current Average Power Factor kwh-del Last Event Date Occurrence/Restoration Outage Log

10 11 12 13 14 15 16 17 18 19 20

Normal / Alternate

Tems

PB stands for Previous Billing. * Displays the previous three months reading. where xx indicates the month. Like 01 For January, 02 for Feb & so on. It will appear in "lastes first" order Also Pdr indicates the reading at the time of Manual Demand Reset (if any)

WBSEBEA - 240

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. Display Identifiers Tis is used to identify the displayed quantity. Except for the energy and power identifiers, these identifiers can be turned on or off using the AlphaPlus software Unoike the numeric identifier, you cannto chagne the display identifier for a displayed quantity. All display identifiers are predefined as follows : ABCD

-

COUNT CUM KWARh

-

MAX PREV

-

RATE RESETS SEAS

-

TOTAL

-

Indicates the rate period A, B, C or D of the displayed data (TOU only) : note that the active rate period blinks when displayed. Indicates a continuous demand reading; with CUM Indicates a cumulative demand value; used with KWARh Selectively, displayed portions of this identifier allows the meter to indicate power or energy as follows : kW, kWh, kVA, kVAh, kVAR, kVARh (the "V" is created by displaying half of the : W") Indicates a maximum demand value; used with kWARh Indicates the previous billing period, or previous season information when used with SEAS Indicates the rate period (TOU only) : used with ABCD Indicates the number of demand resets Indicates the previous season information (TOU only) Used with PREV to form PREV SEAS Indicates a total energy value; used with kWARh

These display identifiers may be combined together in various ways to indicate a particular displayed quantity. For example RATE A kWh = kWh for rate period A (TOU only) : CONT CUM KW = the continuous cumulative kW demand ; MAX KW-the maxinim kW demand.

WBSEBEA - 241

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VARIOUS MODE OF CONNECTION OF ACCUCHEK METER

ACCUCHEK

R

1S

Y

1L 2S

B

N

2L 3S

IR

IY

IB

VR VY VB

N

3L

MUT

R

TO LOAD SIDE

Y B N CLAMP ON CT 3Ø,400 V, 50Hz, AC SUPPLY

ACCUCHEK LT + CHECKING LT CT OPERATED METER USING CLAMP-ON CT (Checking system accuracy including external CTs)

ACCUCHEK

N

P 1S

I

V

N

1L

MUT

TO

PHASE

LOAD SIDE

NUETRAL

CLAMP ON CT SINGLE PHASE 230 V, 50Hz, AC SUPPLY

ACCUCHEK LT +CHECKING SINGLE -PHASE CT OPERATED METER USING CLAMP-ON CT (Checking system accuracy including external CT)

WBSEBEA - 242

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1 Ø 230 V, 50 Hz AC Supply

CLAMP ON CT

PHASE

To Load Side

NUETRAL

MUT

VR 1S 1L

B

ACCUCHEK

N

ACCUCHEK LT* Checking Single Phase Direct Connected Meter Using Clamp-On CT

P

N

1S 1L

P

N

1S 1L MUT

ACCUCHEK

PHASE

To Load Side

NUETRAL

1 Ø 230 V, 50 Hz AC Supply

ACCUCHEK LT* Checking Single Phase LT CT Meter Using 1A/5A Current Range

WBSEBEA - 243

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R

Y

1S 1L

B

2S 2L

N

R

3S 3L

1S 1L

Y

B

2S 2L

N

3S 3L ACCUCHEK

MUT

R To

Y

Load

B

Side

N 3Ø, 400V, 50 Hz, AC Supply ACCUCHEK LT* Checking LT CT Operated Meter Using 1A/5A Current Range

3Ø, 400V, 50 Hz, AC Supply

Clamp-On CT

R To

Y

Load

B

Side

N

1R 1S

1L

2S

2L

3S

3L

N

MUT

1Y

1B

ACCUCHEK

ACCUCHEK LT* Checking Direct Connected Meter Using Clamp-On CT

WBSEBEA - 244

VR

VY

VB

N

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DATA FOR VARIOUS MATERIALS Sl.

Description of work

No.

Stone

Sand

(cum)

(cum)

1.

Plain cement concrete (1:2:4)m3

0.92

0.46

2.

Plain cement concrete (1:3:6)/m3

0.92

0.46

3.

Plain cement concrete (1:4:8)/m3

0.92

0.46

4.

Reinforced cement concrete (1:11/2 : 3)m3

0.92

0.46

5.

Rinforced cement concrete (1:2:4)/m3

0.92

0.46

3

6.

Rough stone dry packing / m

1.10

-

7.

+ R.R. Masonry in C.M. (1:5)/m3

1.10

0.34

8.

R.R.Masonry in C.M. (1:6)/m3

1.10

0.34

9.

Brick work in C.M. (1:4)/m3

Bricks 512

0.20

10.

Brick work inC.M. (1:5)/m3

Bricks 512

0.20

11.

Brick work in C.M. (1:6)/m3

Bricks 512

0.20

12. 13.

Hollow brick masonry in C.M. (1:5)/m3 Plastering in C.M. (1:3) 12 mm thick/10m2

Bricks 52

0.12 0.15

14.

Plastering in C.M. (1:3) 20 mm thick/10m2

Sand = 0.21

Cement=100.80

15.

Flush pointing R.R. in C.M. (1:3)/10m2

Sand = 0.09

Cement =43.20

16.

White washing (One Coat)/10m2

Lime=0.05 Cum

17.

White washing (Two Coats) 10m2

Lime=0.07 Cum

18.

White washing (Three coat) 10m2

Lime=0.091 Cum

19.

White cement (One coat) 10m2

White Cement=

2.00 Kg

20.

White cement (Two coats) 10m2

White Cement=

3.50 Kg

—

2

21.

Snowcem paint (one coat)/10m

Snowcem=

2.00 Kg

22.

Snowcem paint (Two coat)/10m2

Snowcem=

3.50 Kg

23.

Plastic Emulison paint (One coat) OW/10m2

Paint =

0.40 Ltrs.

24.

Plastic Emulsion paint (Two coats) / OW/10m2

Paint =

0.70 Ltrs

25.

Synthetic Enamel Paint-NWW (Two Coats)/10m2

Paint=

1.20 Ltrs.

26.

Synthetic Enamel Paint - OWW (One coat) 10m2

Paint=

0.70 Ltrs.

27.

Synthetic Enamel Paint-OIW (Two Coats)/10m2

Paint =

0.50 Ltrs.

28.

2

Synthetic Enamel Paint - OIW (Two Coats) / 10m

Paint =

1.10 Ltrs.

29.

Synthetic Enamel Paint - OIW (Two Coats) / 10m2

Paint =

0.90 Ltrs.

30. Red Oxide Paint - (One Coat) / 10m2 Paint = $ 30% of the skilled labour provided in the data may be taken as 1st class and remaining 70% as second class. + R.R. Random Rubble; *23x11x7 cm Traditional size burnt clay brick; *40x20x20 cm size cement concrete hollow bric NWW-New Wood Work; OWW-Old Wood Work; OIW - Old iron Work; NIW - New Iron Work, OW - Old Wall/Woo

WBSEBEA - 245

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PLANNING OF

While planning the Building its functional utility, cost, habits, taste, requireme

Size of rooms 1. Drawing room (Living) 2. Bed room 3. Kichen room 4. Dining Hall 5. Bath and WC 6. WC 7. Bath room

Rooms 1. 2. 3. 4.

Living room Kitchen room Bath room WC

Following are the minimum Requirements : Standard type Ordinary Type 4.2x4.8 M to 5.4x7.2 M (14'x16' to 18'x24') 4.2x4.8 M (14'x16') 3.0x3.0 M (10'x10') 4.2x4.8 M to 4.8 to 6.0 M (14'x16' to 16'x20') 1.8x2.5 M (6'x8') -

4.2 x 4.8M (14' x 16') 3.0x3.5 M (10'x12') 2.5x3.0 M (8'x10') Combined drawing and dining room 1.8x1.8 M (6'x6') 1.2x1.2M (4'x4') 1.2x1.8 M (4'x6')

Minimum floor area of Rooms and heights : Floor Area Height 10 Sq. Mtr. (100 Sq. Ft) 6 Sq. Mtr. (60 Sq. Ft.) 2. Sq. Mtr. (20 sq. Ft.) 1.6 Sq. Mtr. (15 Sq. Ft.)

3.3 Mtr. (11') 3.0 Mtr. (10') 2.7 Mtr. (9') 2.7 Mtr. (9')

Minimum height of plinth : 0.60 M (2') Minimum depth of foundation-0.9 M (3') Thickness of Wall : 20 to 35 cms (8' to 10') Minimum aggregate area of opening of habitable rooms and kitchen excluding doors, shall not be less than :' 1) 1/10th of Floor area - for wet hot climate. (2) 1/6th of Floor area - for dry hot climate (3) 1/ 8th of Floor area - for climate which is neither dry hot nor wet hot. Size & Weight of Expanded Metal (XPM) Sheets Size of Mesh Dimensions of Strands Weight Size of Sheet Swm Lwm Width Thickness per sq. m normally mm mm mm mm kg stocked 100 250 6.25 3.15 3.082 75 200 6.5 3.15 4.282 2.5X3.75 25 75 3.25 2.24 4.564 25 75 3.25 1.60 3.262 12.5 50 3.25 1.60 6.525 2.5X2.75 12.5 50 2.5 1.6 5.019 Swm - short way of Mesh Lwm - Long way of Mesh For 10 Users. } Excluding thickness of wan L=1.8m B=0.6m H-1.35 m } Exclucing thickness of botton Stab. 0./15 m to be provided for Fexboard. WBSEBEA - 246

Bottom width (inch)

3.5 4.312 3.937

PARTICULA USERS For 50 User L=3.45 m E B=0.7 m H=1.876 = E to be provid

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BUILDING

ents needs to be paid due attention for, considering funds at disposal

Diameter width mm 5.0 5.5 6.0 7.0 8.0 9.0 10 11 12 14 16 18 20

hickness in mm 5 6 8 10 12 14

Weight of square and round 3ars : 0.7843 Kg/cm2 per metre of 1 cft. of seal 490 lbs. Weight per metre Diameter Weight per metre Square Bar kg Round Bar kg or width mm Square Bar kg Round Bar kg 0.20 0.15 22 3.80 2.98 0.24 0.19 25 4.91 3.85 0.28 0.22 28 6.15 4.83 0.38 0.20 32 8.04 6.31 0.50 0.39 36 10.17 7.99 0.64 0.50 40 12.56 9.86 0.78 0.62 45 15.90 12.49 0.95 0.75 50 19.62 15.41 1.13 0.89 56 21.62 19.34 1.54 1.21 63 31.16 24.47 2.01 1.58 71 39.57 31.08 2.54 2.00 80 50.24 39.46 3.14 2.47 Weight in kg per sq. m. 39.25 47.10 62.80 78.50 94.20 109.90

Weights of MS plates (plain) Thickness Weight in kg. in mm per sq. m. 16 18 20 22 25

Particulars of Rails ght Distance Section Moment Total il in from top Moduli of inertia debth /yd) of rail to about about (inch.) NA (inch.) X-X X-X 2 (inch ) (inch4)

125.60 141.30 157.00 172.70 196.25

Weights of Indian Standard Equal Angles Size ISA Weight in Size ISA Wt. in kg/m kg/mm

65x65x5 4.9 100x100x6 9.2 65x65x6 5.8 100x100x8 12.1 65x65x8 7.7 SS 1.75 3.74 6.55 3.5 50x50x6 4.5 BSS 2.25 5.77 12.98 4.25 50x50x5 3.8 BSS 1.97 5.13 10.10 3.937 75x75x6 6.8 LAR OF SEPTIC TANK FOR DIFFERENT 75x75x8 8.9 80x80x6 7.3 rs For 100 Users Excluding thickness of watt. L=4.35 m Excluding thickness of watt. } Excluding thickness of bottom Slab 0.15 m B=0.85 m H=2.25m - Excluding thickness of bottom Slab 0.15 m to ded as Fxeboard. WBSEBEA - 247 be provided as Fxeboard.

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. SALIENT FEATURES OF REGULATIONS FRAMED BY WEST BENGAL STATE ELEETRICILY REGULAR COMMISSIONS TILL JAN' 2005 AS PES EA-2003 APPLICATION FOR SUPPLY Application by any person, firm or company for New Service/New Load of Existing Service/Additional Load/Shifting or alteration or Strengthening of Service/Street Lighting/Pump House (Temporary and Permanent connection) must be made to the West Bengal State Electricity Board in prescribed format in duplicate as mentioned hereunder. The prescribed format for application for Supply-Cum-Agreement is obtainable free of cost from: Voltage of supply

Office

Low & Medium Voltage Supply (Installed capacity upto 50 H.P)

Group Electric Supply Office.

High Voltage Supply (Contract demand between 50KVA & 500 KVA)

Distribution Circle Office

High/Extra HighVoltage Supply. (Contract demand above 500 KVA)

Central Commercial Department Bidyut Bhavan.

At the time of application the prospective consumer has to make provisional payment in advnce against charges payable for the supply as shown below. Consequent upon making detailed calculation, necessary adjustment will be made through refund / realisation in the first energy bill. (i) (ii) (iii) (iv)

For Single phase L.T. Supply Rs. 2,000/- (Rupees two thousand only) For two phase L. T. Supply. Rs. 3,000/- (Rupees three thousand only) For three phase L.T. Supply. Rs. 4,000/- (Rupees four thousand only) For H.T. Supply upto a contract Rs. 50,000/- (Rupees fifty thousand only) demand of 125 KVA (v) For H.T. Supply above a contract Rs. 2,00,000/- (Rupees two lakh only) demand of 125 KVA The prospective consumer has also to make payment in advance against security deposit as below. After the final calculation of the requisite security deposit, the advance will be adjusted through the first energy bill. (i) 0 - 500 W @ Rs. 300/- only (ii) 500 -1 KW @ 500/- only (iii) For every additional KW or part thereof. @ Rs. 500/- only All industrial consumers shall have to produce the consent of the West Bengal Pollution Control Board before effecting power supply by the Board. ENFORCEMENT MECHANISM :If the Board fails to meet the specified guaranteed standards against various service areas laid down in these R egulations, the Board shall be liable to pay compensation to the consumer (s) for default against each item as specified below : Item (a) Failure to release new electric connection with due time (b) All other specific complaints specified under paragraphs 17.1, 18, 19 and 20

Year of Regulation's operation 1st year 2nd year 3rd year and thereafter

Amount of compensation Rs.25/- for each additional day Rs.125/- for each additional day Rs.500/- for each additional day

1st year (Urban & Rural) 2nd year (Urban & Rural) 3rd year and thereafter (Urban & Rural)

Rs.25/- for each addl. slab of time Rs.125/- for each addl. slab of time Rs.500/- for each addl. slab of time

WBSEBEA - 248

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WBSEBEA - 249

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. DISCONNECTION FOR DISTRESS OR DAMAGE TO THE ELECTRICAL PLANTS, ELECTRIC LINES OR METER (a) The Board may disconnect the supply of electricity if the consumer uses any appliance or equipment or uses the energy in such a manner as may endanger the Board's service lines, supply mains, meters and other plants / equipment and works of the Board. However a notice in writing of not less than 24 hours shall be given to the consumers before such disconnection along with the reasons / cause of such disconnection. (b) The supply may be disconnected normally if the cause for the same is not removed within the notice period. (c) In emergent circumstance the Board may disconnect even within the notice period or without notice, if continuation of supply is likely to endanger supply mains, service lines and other plants or equipment or the work of the Board or endanger the life. In such a case the employee of the Board who is taking the decision to disconnect shall submit a report within 24 hours of disconnection to a officer not below the rank of Executive Engineer in case of L.T. supply and Superintending Engineer in case of HT supply. (d) The decision to issue the notice of disconnection shall be taken at appropriate level which shall not normally be less than an Assistant Engineer. DISCONNECTION ON REQUEST (a) The Board shall disconnect the supply of energy to a consumer within two (02) working days of making such request by the consumer. It shall be the duty of the consumer to clear all the outstanding payments payable by him to the licensee except the last bill for supply till the date of disconnection before making request for such disconnection. However, this should not hold for disconnection of supply by the Board and for any non payment the consumer may continue to be treated as consumer in default for the purpose of Regulation prescribed under clause 29 regarding 'Disconnection of Supply'. REDRESSAL OF CONSUMERS' GRIEVANCES In accordance with the West Bengal Electricity R egulatory Commission (guidelines for Establishment of Forum for redressal of Grievances of Consumers and Ombudsman) Regulation, 2003, a 3-Tier forum for redressal of consumers' grievances has been constituted by the Board. Tier -1 The Tier-1 of the forum for redressal of Grivevances h as been constituted at the office of each Circle Manager at Distribution Circle headed by the Divisional Engineer/Superintending Engineer (Electrical) attached with the Distribution Circle Office and designated as Circle Grievance Redressal Officer (CGRO). The consumer should approach Tier-1 initially within 2 months of the last of the period for which the grievance relates and his written grievance will be registered, acknowledged and a grievance no will be given. The grievance will be attended promptly, normally within 7 days from the date of receipt and in case it involves consultation with the other officers or needs a technical scrutiny then a provisional reply will be sent informing the consumer that his/her complaint is being looked into. Complaints of this type will be finally disposed off usually within 21 (twenty one) days from the date of receipt of the complaint from the consumer. Normally the Grievance Redressal Officer should deal with complaints without insisting upon the personal presence of the complainant. However, if the complainant desires to be heard in person and the Grievance Redressal Officer is of the opinion that it is necessary to give the complainant a hearing or if the Grievance Redressal Officer is not able to fully understand the grievance he may either talk to the complainant on the telephone to understand his problem and in required case he may ask consumer to come to the office. The decision of the Grievance Redressal Officer should be duly intimated to the consumer. In case the request of the consumer is not accepted, then the detail reasons will be given. During disposal of grievances the provisions of the Electricity Act, 2003, Rules and Regulations made thereunder shall be kept in view and fuly followed.

WBSEBEA - 250

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. Nothing contained in this guideline shall affect the rights and privileges of the consumer under any other law for the time being in force. In case the consumer has filed and application/case in any Consumer Forum or Court, the same has to be mentioned with all relevant details in the application. Tier-2 In case the consumer is not satisfied with the outcome of his complaint at tier-1 he may approach to tier-2 with all the r elated correspondence of Tier-1. Procedure is similar to that of Tier-1. The Tier-2 of the forum for redressal of Grievances has been constituted at the Distribution Zonal Office headed by one Superintending Engineer (Electrical) and designated as Zonal Grievance Redressal Officer (ZGRO). Tier-3 If the consumer is not satisfied with redressal at Tier-2 he may approach to Tier-3 with all related correspondence with Tier-1 and Tier-2 and the reply of the complaint shall be given within 7 days of the receipt of the grievance. The Tier-3 of the forum for redressal of Grievances has been consituted at the Corporate Head quarter at Vidyut Bhawan headed by the Chief Engineer (Corporate) and designated as Principal Grievance Redressal Officer (PGRO). Ombudsman Any consumer aggrieved by an order made by the Forum for redressal of Grievances of the consumers after Tier-3 may prefer an appeal in writing in the prescribed form as attached at the end of this charter within 15 days of the receipt of such order to the 'Ombudsman' appointed by the Hon'ble West Bengal Electricity Regulatory Commission. PLANNED INTERRUPTIONS. When there is a planned interruption of supply lasting more than 6 hours at a stretch, the Board shall notify the consumers at least 24 hours before the supply is cut off through announcements in radio / T.V., advertisement in leading dailies, beating of drums etc. and restore the supply within the time to be anounced. If the planned interruption is for more than 12 hours at a stretch, temporary arrangement will be made to provide power after 12 horus.

1. SERC Regulation No.

Subject

Notification Date

10/WBERC

Guidelines for Establishment of forum for Redressal of Grivences of consumer and Ombudsman

Remarks

23/09/2003

11/WBERC

Miscellaneous provision

12.11.2003

Clause of security depsosit

12/WBERC

Conduct of Business

12.11.2003

Tariff petition related format

13/WBERC

Electricity Supply Code

05.02.2004

15/WBERC

Phasing of open Acess in distribution/sale of Electrticity Standereds of performance of licensees relationg to consumer services Licensing & Conditions of Licences Tariff

16/WBERC

17/WBERC 18/WBERC

09.06.2004

09.06.2004 09.06.2004 09.06.2004

WBSEBEA - 251

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Sub section (1) of section 127 of EA 2003 the officers of WBSEB function as appellate authority (1) for L & MV consumers (2) For decentralised Bulk Consumers (3) For Centralised Bulk Consumers

Circle Manager CE (Dist) C.E. (Commercial)

3.

Sub section (1) of section 152 of EA 2003 the officers of WBSEB authorised for compounding of offence (1) for L & MV consumers Zonal Manager (2) For decentralised Bulk Consumers C.E. (Dist) (3) For Centralised Bulk Consumers C.E. (Commercial)

4.

Section 152 of EA, 2003 the Station Manger, D.E. & S.E. of WBSEB au thorised as Assessing Officer

VSAT TECHNOLOGY Very Small Aperture Terminal (VSAT) based Wide Area Network (WAN) is used for Voice & Data communication. The Network in WBSEB uses INSAT-3C satellite and operates in Extended - C band with uplink frequency band of 6921.5 - 6926 MHz and downlink frequency band of 4696.5 - 4701 MHz. The Network operates in Star / Mesh configuration for Data / V oice communication. The TDM/ TDMA data & voice connectivity works in star confirguration. In star confirguration the connectivity between two remote VSATs is always routed through Central HUB. The inbound (VSAT to HUB) information rate is 64 Kbps (which may be increased in future). The Outbound (HUB to VSAT) information rate is 512 Kbps. Mesh voice & data connectivity is provided using SCPC carriers in DAMA. In a mesh topology, the Central HUB establishes the link between two remote VSATs and after that the VSATs communicate directly with each other without any intervention of the Central HUB. Network Management System at HUB station performs the network monitoring, control and management operations from a system operator console. Management functions at the HUB station include provision of multipoint connections between HUB station and several VSATs such that monitoring and control of the VSATs can be effected continuously. The Network uses following multiple access protocols as per traffic requirements at different sites :A. TDM/TDMA : TDM/TDMA data network is engineered in star configuration with HUB facility at one central location and VSAT facility at other remote locations. The HUB provides both point to point or point to multipoint connectivity. VSATs communicates with HUB directly. However VSAT to VSAT communication is possible only via the HUB. The (TDMA) link from remote to HUB is called Inroute and the (TDM) link from HUB to remote is called Outroute. Central HUB transmits single outroute carrier, containing data pakets, to all remote sites in Time Division Multiplexed form. Data packets in outroute stream carry addresses of specific remotes to which they are aimed. The remote VSAT electronics receives the TDM stream and picks up data packets addressed to it. Remotes transmit to HUB through shared inroute channel in Time Division Multiple Access (TDMA) format. The inroute is divided into a number of time slots. Different sites transmit at different times to avoid collision.

WBSEBEA - 252

Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. B. DAMA NETWORK : Demand Assigned Multiple Access (DAMA), SCPC works on Frequency Division basis where each earth station is allocated a unique frequency pair to communicate with other station. This allocation is done on demand after user requests for a connection. The network uses a pool of satellite channels, which are available for use by any station in the network. On demand a pair of available channels are assigned so that a call can be established. Once the call is completed, the channels are returned to the pool for an assignment to another call. HYBRID NETWORK : Hybird Network is a combination of DAMA and TDM/TDMA network. VSAT ELECTRONICS : The VSAT Electronics consists of Antenna, Solid State Power Amplifier (SSPA), Low Noise Amplifer (LNA), Up Converter, Down Converter, Indoor data & voice units and IF combiner / splitter electronics. Antenna size, SSPA rating and LNA depend upon the number & type of voice & data circuit that a VSAT shall support. The Indoor unit and the Outdoor unit are interconnected with IFL cable which is capable of carrying both signal and DC power required for the operation of Outdoor electronics. HUB ELECTRONICS : The HUB electronics consists of RF electronics and base band equipment. RF electronics consists of TWTA, Up Converter, Down Converter and LNA. The base band & IF electronics consists of Modulator, Demodulator, Coder, Decoder, HUB protocol processor, DAMA and TDM/TDMA NMS. The HUB protocol processor supports variety of protocols and data rates and interfaces to NMS. The protocol procssor converts the user protocol to space protocol for transmission over the satellite link. The packet switching exchange at the HUB does switching of data packets from one VSAT to other VSAT. The HUB base band equipment procesds inbounds signal received from various VSATs and generates TDMA outbound signal for transmission over satellite link. The outbound data is coded using FEC 1/2, modulated to IF frequency and fed to RF electronics. In the receive direction the inbound is demodulated, decoded and the resulting data passed to HUB processor. The RF electronics provides iterface between HUB base band equipment and satellite. The Up Converter converts the IF signals to satellite frequency and fed to TWT amplifier for amplifying to required level. In the receive direction, the RF signals received from satellite are amplified by LNA and Down Converted to IF frequency by Down Converter and fed to the IF and base band unit for further processing. The DAMA controller at the HUB provides allocation of pair of frequencies from the available pool to the originating and destination VSATs. DAMA controller supports inbound common signaling channel and outbound common signaling channel. NETWORK MNAGEMENT SYSTEM (NMS) : Network Management System performs the task of network operations and management. NMS provides the following facility : 3 Monitoring network status. 3 Configuration of all network components including VSATs. 3 Downloading of operational software to network components from Central HUB. 3 Recording detailed statitics of traffic, both network traffic and renmote traffic. 3 Recording details of network operations like events, billing and statistical data. 3 Fault diagnosis and display of alarms. 3 Generation of reports regarding configuration, faults, alarms, events and statistics.

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OVERVIEW OF THE TECHNICAL SPECIFICATIONS CENTRAL HUB : Antenna Size

:

9M

Antenna Transmit Gain

:

54.4 db.

Antenna Receive G/T

:

31.7 dB/deg K

Frequency Range

:

Transmit 6.7-7.025 GHz. Received 4.5 - 4.8 Ghz.

TWTA Power Out Put

:

400 W.

FEC Coding

:

Rate 1/2 Conolutional Coding and Sequential Decoding.

Modulation

:

BPSK / QPSK.

HUB Based Interface :

:

LAN Port _ IEE 802.3, UTP Port. Telephone/EPABX-FXS, FXO, 4 Wire E & M.

Inbound Data Rate

:

64 Kbps, and be upgraded to 128 Kbps.

Outbound Data Rate

:

512 Kbps.

Data Broadcast

:

IP over LAN.

Access Mechanism

:

Slotted Aloha, Pure Aloha, Transaction Reservation.

TDM/TDMA VSAT Antenna Size

:

1.8M

Antenna Transmit Gain

:

40.3 db.

Antenna Receive G/T

:

15 dB/deg K

Frequency Range

:

Transmit 6.7-7.025 GHz Received 4.5 - 4.8 GHz

SSPA Power Out Put

:

5W

FEC Coding

:

Rate 1/2 Convolutional Coding and Sequential Decoding

Modulation

:

BPSK/QPSK.

IDU Interface

:

Serial Port - V.35 64 Kbps, RS-232 19.2 Kbps,

:

LAN Port-IEE 802.3, UTP Port.

:

Telephone/EPABX-FXS, FXO, 4 Wire E & M.

Protocols supported

:

TCP-IP, X.25, SLIP.

Access Mechanism

:

Slotted Aloha, Pure Aloha, Transaction Reservation.

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HYBRID VSAT Antenna Size

:

3.8 M

Antenna Transmit Gain

:

46.9db,

Antenna Receive G/T

:

23.6 dB/deg K

Frequency Range

:

Transmit 6.7-7.025 GHz Receive 4.,5-4.8 GHZ

SSPA Power Out Put

:

5W.

FEC Coding

:

Rate 1/2 Convolutional Coding and Sequential Decoding.

Modulation

:

BPSK/QPSK.

IDU Interface

:

Serial Port-V.35 64 Kbps, RS-232 19.2 Kbps,

:

LAN Port - IEE 802.3, UTP Port

:

Telephone / EPABX-FXS, FXO, 4 Wire E&M

Protocols supproted

:

TCP-IP, X.25, SLIP, Clear Channel.

Access Mechanism

:

Slotted Aloha, Pure Aloha, Transaction Reservatio.

GLOSSARY : BPSK

:

Binary Phase Shift Keying.

DAMA

:

Demand Assigned Multiple Access.

FEC

:

Forward Error Correction.

G/T

:

Gain/Temperature.

IF

:

Intermediate Frequency.

IFL

:

Inter Facility Link.

LAN

:

Local Area Network.

LNA

:

Low Noise Amplifier

NMS

:

Network Management Software.

QPSK

:

Quardrature Phase Shift Keying.

RF

:

Radio Frequency/.

SCPC

:

Single Carrier Per channel.

SSPA

:

Solid State Power Amplifier.

TDM

:

Time Division Multiplexing.

TDMA

:

Time Division Multiple Access.

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"E-SURAKSHA-A PRACTICAL APPROACH IN NETWORK SECURITY" To get a clear idea on computer security, three main concept : threat, vulnerability and attack, is to be discussed. * Threat - A threat to computer system security is a possible act which can effect the system itself or the information stored within the system. * Vulnerability - In a computer system, it is a weak point which makes such a threat possible. * Attack - It is an action performed by an attacker with the aim of finding and exploiting some of the vulnerabilities. Three basic types of security threats are there. 1. Threat of Exposure - This arises due to the fact that inforamtion is revealed to a person who should not know it. 2. Threat of Integrity - This includes any intentional change (modification or even deletion) of data stored in a computer system of transferred from one system to another. 3. Denial of Service - This threat is present every time access to some resources of computer system is blocked due to certain actions. In real life, the block or obstruction can be permanent. System Administrator should know the possible methods used by the Hackers / Crackers to break into the systems and best practices in order to defend against attacks. A System Administrator should also know about the following examples of system vulnerabilities to rectify himself accordingly. # Lack of Firewall and inadequate firewall policies. # Inadequate network management. # Not using the latest version of operating system one can lead to exploitation of security weakness. # Not keeping up to date with various online security. organizations, such as CERT will lead to a known weakness not being corrected in a timely manner. # Unencrypted Communications. # Lack of Physical security over data communication closets or hubs. # No antivirus Software, lack of r egulr update of Antivirus Softw are and inadequate education of staff on virus. # Uncontrolled downloading and use of software off the internet. # Lack of policy on reopending of email attachments and using floppy disks before scanning by Antivirus Software. # Lack of Intrusion detection software. # Lack of update of operating system security patches. # Unrestricted use of modems of dial into the network and lack of inventory of dial up lines leading to inability to dial up access. # Lack of time restriction on user access and lack of dial back authentication. # Lack of policy restricting the provision of information by staff over the phone. # Lack of policy requiring all enquiries for information to be withheld until the identity of the requestor can be verified. Vigilance is best maintained by tracking security issues closely. Monitoring of vendor security information and independent security websistes and mailing lists are required. Some important websites, which should be visited regularly by a good network administrator are as follow : * www.securityfocus.com - For Security Focus. * eve.mitre.org(By MITRE Corporation)-For getting list of common vulnerabilities and Exposure list. * www.cert.org/(By CERT) * www.ciac.org/ciac(By CLAC)

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Please purchase PDFcamp Printer on http://www.verypdf.com/ to remove this watermark. Cryptology It is the art and science of "secret writing" - provides ideal methods to solve these problems of data security in net. Cryptology is divided into two branches - cryptography and cryptanalysis. Cryptography is the science, which embraces all the methods and devices whereby an intelligible, wirten message may be converted into unintelligible or secret form. Cryptography, to most people, is concerned with keeping communications private. The most important automated tool for network and computer security is encryption. Encryption is the transformation of data into some ureadable form. Its purpose is to ensure privacy by keeping the information hidden from anyone for whom it is not intended, even those who can see the encrypted data during transmission of the data in the net. Decryption is the reverse of encryption, it is the transformation of encrypted data back into some intelligible form to authenticated acceptor. Cryptanalysis , on the other hand, is the sc ience, which embrances all the principles, methods and means employed in the analysis of secret messages (cryptograms). The explosive growth in computer systems and their interconnections has inceased the dependence of both organizations and individuals on the information stored and communicated using these systems and these computer hosts are accessible in a variety of ways, including gateways, routers, dial-up connections, and internet service providers. Individuals and organizations worldwide dcan reach any point on the network without regard to national or geographic boundaries or time of day. However, along with the convenience and easy access to information come new risks. A mong them are the risks that valuable information will be lost stolen, currupted or misused and that the computer systems will be corrupted. This led to keen awareness of the need to protect data and resources from disclosure and to guarantee the authenticity of data and messages and to protect systems from network based attacks. The area of cryptography has matured leading to the development of practical, readily available standards, protocols and applications. A security protocol is a communication protocol that encrypts and decrypts a message for online transmissio. Security protocols generally also provide authentication. Some of the readily available protocols to enforce net work security are PG, Kerberos, SSL/TLS, SHTTP, IP Sec. S/MIME etc. Different types of cryptographic algorithms like RSA, Digital signature, Digital certificate etc are used for security. FIREWALLS A firewall is a barrier between two networks (or even two hosts) which have different security requirements. A firewall is normally placed between the corporate network and internet. It is always better to install two firewalls for improved protection. If one of the firewall becomes dysfunctional, the other will ensure protection until the first firewall is recovered. Security monitoring is a continuous process. There should be a regular search for different possibilities of vulnerabilities and vulnerabilities should be immediately patched to avoid any attack. Sat isfaction about system security should never come into the mind of the system administrator. In WBSEB one Wide Area Network (WAN) is already running using SATCOM network. In this network all DCC or WBSEB are connected. Valuable L & MV, BULK billing data and PIS data of different employee of the Board are there is DCC. So, security of these data may be given as the highest priority. Moreover, this is a age of customer satisfaction. To give the customer satisfaction, bill collection facility from all of our collection centers is to be provided to customrs from any corner of West Bengal. At the same time, Website is to be available to consumers for billing data and payment collection. So, we have to be very security conscious, specially when our data will be in net. Proper security policy may be designed before placing the data in website to avoid any inconsistency. A special security team may be formed to monitor these activities.

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References 1. Lectures note of Er. Aloke Roychowdhury (WBSEB) 2. Lectures note of Er. B. Sengupta (WBSEB) 3. Lectures note of J. R. Nanda, K. R. Krishnaswamy, R. K. Kumar, R. Pannur Selvam of Central PowerResearch Institute, Bangalore 4. Lectures note of Er. Uma Chakraborty (WBSEB) 5. Lectures note of Er. P. K Pradhan (WBSEB) 6. Jvs relay manual - Publication No. JR302-1 7. English Electric Relay Manual 8. Power News flash of Reamker - February - 2004 9. Lectures note of Er. J. C. Mondal (WBSEB) 10. Lectures note ofEr. D. P. Chakraborty (WESEB) 11. Exide Battery Manual 12. Manual of Power Supply Under taking (TSSA, WBSEB) 13. WBSEBEA Journal '96 14. ABB Alpha Motor user's manual 15. MRI operating man ual, Verson - 2.02 (secrme) 16. MRI (Smile) operating manual, Version, 1.00 (secme) 17. Accuatek user manual 18. Lectures note of Er. A. K. Mitra (WBSEB) 19. Lectures note of Note of Er. Dipankar Basu & Er. Kumkum Majumder (WBSEB) 20. Note of Er. Shyamal Das (WBSEB) 21. Note of Er. Sudip Ghowh ) (WBSEB) 22. Note of Er. Biswajit Chatterjee (WBSEB)

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