Electrical Data

CHAPTER 21

DATA ON ELECTRICAL SYSTEM 1. Introduction 2. Data on Electrical Circuit Study 3. Data on Protection Scheme 4. Data on Electrical System Equipment 5. Transmission Line Data 6. Transmission Line Conductor Data 7. Data on Electrical Clearances 8. Electrical Earthing System Data 9. Data on Distribution System ( Up to 33 KV System ) 10. Data on Sub- Station 11. Electrical Standards 12. Data on Power Telecommunication 13. Meaning s of Indications for Different Distance Protection Relays 14. Diagnostic System/ Maintenance Scheduled Of Electrical Equipment 1.

Introduction:-

Data on the Electrical System are the most useful tool for the Electrical engineers to know the limit of their working arena. According to the limitation of Data, proper planning, estimation and confirmation regarding the equipments can be achieved. Basically the practice Engineer are very cautious regarding the value of threshold on the Electrical Parameters, upon the field works on the Equipments on which they work to obtain the efficiency of the assigned project. Many a times they get confused to land upon a decisive conclusion; due to the non-availability of ready reckon electrical data. This chapter has covered all the possible zones of electrical field topics with some reference data in concise manner. The reference tips on the maintenance schedule, testing methods, installation practice and commissioning patterns can help the Electrical Engineers to acquaint themselves and develop a healthy environment by refining their practice towards the field works.

2.

DATA ON ELECTRICAL CIRCUIT STUDY

2.1 STANDARD CONNECTING WIRE LETTERS A

PURPOSE

LETTERS M

CT Secondary

PURPOSE Motor Control Circuit

Circuit special B

Bus Bar Protection

C

Protection AC

N

Transformer Tap Changer

Circuit (CT )

S

Control Circuit

D

Metering Circuit

Marking of Sec.

E

PT Secondary

CT Polarity

F

Fan Control Circuit

H

LT AC Supply

J

DC Main Circuit

K

Control (Trip, Close

U

wires X

Used for spare wires

etc L

Used for spare

Alarm, Indication, Annunciation Circuit

2.1

DEVICE IDENTIFICATION CODE CODE NO. 1 2 3 4 9 12 13 14 20 21 22

FUCTION /DEFINITION

Master Element Time Delay Starting or Closing Relay Checking or Inter locking Relay Master Contactor Reversing Device Over Speed Device Synchronous- Speed Device Under Speed Device Electric Operated Device Distance Protection Relay Equalizer Circuit Breaker

CODE NO. 23 25 26 27 29 30 34 37 40 43 47 49 50/50N 51/51N 52 52a/52b 53 54 55 57 59 60 61 63 64 65 67/67N 68 69 72 74 76 78 79 80 81 83 85 86 87 88 89 90 91 92 94 95 96

FUCTION /DEFINITION Temp. Control Device Synchronism Check Device Apparatus Thermal Device Under voltage Relay Isolator Contactors Annunciation Relays Motor Operated Sequence Switch. Under Power Relay Field Failure Relay Manual Transfer Selector Switch Phase Sequence Voltage Relay Thermal Relays (Machine/ Transformer) Instant O/C Relay/ Instant E/F Relay AC Time Delay O/C Relay/ E/F Relay AC Circuit Breaker CB Aux. Switch – N/O, CB Aux. Switch – N/C Exciter of DC Generator Relay High Speed DC Circuit Breaker Power Factor Relay Short Circuiting Or Ground Device Over Voltage Relay Voltage Relay Current balance Relay Liquid- Gas pressure level Relay (Buch.) REF Protective Relay Governor AC Directional O/C Relay / E/F Relay Blocking Relay Permissive Control Device DC Circuit Breaker Alarm Relay Dc O/C Relay Phase Angle Measure/ OUT of Step Protn. AC Reclosing Relay DC Fail Supervision Relay Frequency Relay Automatic Sel. Control / Transfer Relay Carrier or Pilot wire Receive Relay Master Relay (Locking –out Relay) Differential Protective Relay Aux. Motor or Motor Generator Line Switch (Isolator) Regulating Device Voltage Directional Relay Power Dir. Relay Tripping or Trip free Relay Trip Circuit Supervision Relay Tripping Relay

2.2

SYMBOLS USED SL. No

Symbols

1.

Meanings

Over Current

2

V

Over Voltage

3

V

Under Voltage

4

Z

Distance Relay

5

X

Balanced or Diff. Current

6

Over Frequency

7

Under Frequency T

8

Over Temp.

9

Balanced Phase X

10

Pilot Wire PW

11

Dirr. O/C Z

12

Dir. Distance CC

13

Carrier Pilot O/c Ground with Instant Element

14 I

15

B

X

16

B X

Bus Current Diff. Bus Ground Diff.

2.4.

SYMBOL AND DESIGNATIONS BASED ON THE (INTERNATIONAL ELECTRO TECHNICAL COMMISSION STANDARD) IEC 617 - SERIES AND IEEE C37.2 – 1991 2.4.1 GENERAL BLOCKS Symbols

Meanings

*

Protection relay

Coil with flag indication (ON)

Protection relay with enable input

Coil with no flag

* EN

* EN

Protection relay with blocking input

I

Coil with flag indication (OFF) Direction E/F current relay with one input (current) and after (voltage), and one for block

Symbols

3I>

Meanings

3phase O/C relay with settable delay

Under impedance relay

EN

Z< Relay with mechanical contracts (Auto reset

2.4.1 PARAMETERS, SYMBOLS AND FUNCTIONS Symbols I

Meanings Reverse current

Symbols I

Meanings Drop out delay

Id

Differential current

Inverse time lag characteristics

Inf

Step

I2 , In

Current of nth Harmonic Positive sequence current - Xe sequence current

I0 , Ip

Zero sequence current

O

I

Residual current

I

O

I1 , Ip

Irsd

LO

Lockout

TCS

Trip circuit supervision Transition from OFF to ON position (e.g.: Auto reclose Tripping

Id IN-N

Current to frame

IN Iub

Current between neutral and two poly phase system Current on neutral Unbalance current

U

Thermal effect by current Voltage

X/Y

Translation of signal

>

Operation above a set value

< > <

Operation below a set value Operation outside set limits (e.g. voltage regulation) Make contract (Self reset) (Normally open) Break contact (Self reset) (Normally close)

P

Active power

Change over contract (Break before make)

P

Power at phase angle

Time delay (drop off)

Q

Reactive power

Time delay (pick up)

Temperature

Normally open contract (Hand reset)

Fault, Flash over.

Normally close contact (Hand reset)

Thermal effect

Positional contact (Bold marked position in considered)

Delay

Push button (Normally open)

P.T, V.T Push button (Normally close )

Isolator

Fuse

Breaker

C.T.

CVT

Wave trap

Note: For study of drawing, the index, legends etc. are to be referred always

2.5 CODE OF PRACTICE BY M/S ABB LTD. 2.5.1 TERMINAL BLOCKS EXTERNAL CIRCUIT TB PURPOSE X01 CT Circuit X02 PT Circuit X03 DC Supply X04 Control Circuit X05 AC Supply X07 Annunciation, AlarmCircuit

INTERNAL CIRCUIT TB PURPOSE X11 CT Circuit X12 PT Circuit X13 DC Supply X14 Control Circuit X15 AC Supply X17 Annunciation, AlarmCircuit

2.5.2 EQUIPMENT/ DEVICE TERMINAL IDENTIFICATION FOR M/S ABB LTD 2.5.2.1 Modular identification: - It is designated by co-ordinate system of U and C/TE U Height of module C/TE Horizontal distance between mounting holes (width of module) Note: Modular's upper left corner U and C/TE co-ordinate is taken. 01

17

25

37

1 2 3 101

325

137

2.5.2.2 Modular Terminal Identification E.g.101: 26 137: 321 325: 222

101, 137, 325 - are modular number 26, 321, 222 - Terminal number

Note: For detail refer combiflex identification. IN ABB MANUAL

3.

DATA ON PROTECTION SCHEME 3.1 CLASSIFICATIONS • Apparatus Protection (Generator, Motor, Transformer, breaker etc.. ) • Bus Protection • Line Protection 3.2 GENERATOR PROTECTION 3.2.1 Class A Protection

INITIATION OF RELAYS

32 G

INTERMEDIATE AUX. RELAY

ACTION OF CIRCUIT BREAKER Trip Gen. CB

&

87G 87GT 87UAT 64G1 64G2 59G 99GT 64REF 51UAT 50UAT 64R II STAGE Rotor Over Voltage Excite Transf. O/C Buch. PRDS GT1,UAT1

Class A Trip Relay 86G

Trip Field. CB Trip Turbine Trip UAT BkrA Trip UAT BkrB Initiate 6.6 KV CB Initiate LBB Arm- Reheater Protection Block Closing of Gen. CB Block Field CB

3.2.2 Class B Protection INITIATION OF RELAYS INTERMEDIATE AUX. RELAY

ACTION OF CIRCUIT BREAKER

46G 40G 21GB (II STAGE )

81

TRIP TURBINE

GCB (OPEN) STATER CONDN. HIGH WATER FLOW LOW

Class B Trip Relay 86T

AUTO & MANUAL PULSE FAIL

TRIP UAT CB Initiate 6.6 KV CB

THYRISTOR COOLING FAN SUPPLY FAIL FCB CLOSE

TRANS. OIL TEMP. &

ARM.REHEATER PROTECTION

WINDING

3. 2.3 Class C Protection INITIATION OF RELAYS 81U/F B/B PROTECTION 21GB IST. STAGE 46G IST STAGE SING. GT 98G (POLE SLIP)

INTERMEDIATE AUX. RELAY

ACTION OF CIRCUIT BREAKER TRIP GEN. CB H.P/L.P BYPASS FAST OPN.

Class C Trip Relay 86 GB INITIATE LBB

3.2.4

Proposed Protection Equipments for different types of Generators

Generator Size Protection

I 0–4 MVA

II 4 –15 MVA

III 15 – 50 MVA

IV 50 – 200 MVA

Rotor Overload X X X X Rotor E/F 4 X 4 X 4 X Inter turn Fault X X X Differential Generator X X X Diff. Block Transformer 3 X 3 X 3 X Under frequency X X X X Over Voltage X X X X Stator E/F X X X Loss of Excitation X Pole- Slip (Out of Step) 1 X 5 X 5 X 5 Reverse Power X X 2 X Under Impendence X 7 X 7 X Unbalance (I2 Current) X 6 X 6 Over Current (Definite Time) Stator Over Load 6 X 6 Over Current / X Under Voltage X X Dead Machine X X Breaker Failure Note: - 1- Only necessary for Steam and Diesel Drives 2. Only necessary for Thyristor excitation from Generator terminals 3. Only necessary for Pump operation. 4. Only necessary for when several Bars of the same phase in the same slot 5. Not necessary for PELTON turbines 6. O/ C should not be used with self supported static excitation system 7. When unbalance load is expected 8. X- Required

V Large Turbo Alternator X X X X X 4 X X X X X X X

X

X X

3.2.4

THERMAL PLANT UNIT PROTECTIONS

SL. BOILER PROTECTION NO 1 Loss of unit critical DC Power 2 Less than fire ball Loss of AC at any elevation in service 3 Very low drum water level for more than 5 Secs 4 Very high drum water level for more than 10 Secs 5 Failure of both FD fans

TURBINE PROTECTION Protection System Power Failure Low Condenser vacuum (2 Channels)

GENERATOR PROTECTION Generator Differential Protection Overall Differential protection

Thrust bearing Oil pressure high (2 Channels) High Shaft vibrations

UAT’ s diff. Protection

6

Failure of both ID fans

7

Unit air flow as low as 30 %

Main steam Temp. Very low High exhaust steam Temp.

8 9

Furnace pressure very low High furnace pressure

10 11

Loss of Fuel (3 out of 4 nozzle valves open) Unit flame failure trip

12

Loss of Re-heater protection

13

Loss of 220 V DC

14 15 16 17

18 19

Electrical over speed

Over frequency Protection Digital Electro hydraulic control power failure Failure of CWPS All valves mainly main stop valve, reheat stop valves, interrupt control valves closure Under Frequency Protection Reverse power protection Mechanical Over speed protection Low auto stop Oil pressure Reheat protection ATRS emergency turbine trip

Over fluxing protection Loss of Excitation protection Negative phase sequence protection Backup Impendence protection Over voltage protection Under Frequency Protection Over Load protection Pole stop Protection

Generator Under voltage associated with loss of excitation protection 95 % back charging stator E/F protection 95 % stator E/F protection 100 % stator E/F protection Excitation field protection Dead machine relaying under independent GCB closure Protection of VT fuse Protection for GT restricted E/F Protection

3.3 MOTOR PROTECTION 1 O/L Protection 2 S.C. Protections 3 E/F Protections 4 Start Protections 5 Prolonged starts 6 Stalling protections

During starting During running

7 Loss of load 8 Under voltage protection 3.4 TRANSFORMER PROTECTION 3.4.1 Requirement of relays CAPACIT BACK UP GAS Y OF OPERA TRANSFO TED RMER RELAY

UP TO 5 MVA 5 to 12.5 MVA ABOVE 12.5 MVA AUTO TRANS.

3 O/ C

2 O/ C

E/F

-

R

R R Dir. R Dir. Inst.

TEM DIF P F PRO REL TEC AY TION O P O W S R T TI R V I

RE F RE LA Y

NEUT. DISPL RELA Y

NEUT. O/C

OVE R FLU X

RELA Y

R

B U C H R O - R

R

O

O

-

O

-

-

R

R

R O R

R

R

O

O

R

O

-

R Dir. R Dir. Inst.

R

R R R

R

R

R

O

O

R

R

R R R R

R

R

-

O

R

-

R - REQUIRED, O – OPTIONAL (--) NOT REQUIRED

3.4.2

CIRCUIT FOR DIFF. PROTECTION (TRANSFORMER ) Sec. CT Transformer Transformer Sec. CT Remark Diff. Winding Winding Diff. Connection Connection Connection Connection Dy1 Y1d Y d1 D1y 1. D1 Yd11 Dy11 Connection corresponds ( IR - IB) Dy11 Y11d Y d11 D11y 2. D11 Yd1 Dy1 Connection corresponds ( I R - Iy ) PRIMARY SIDE P2 TERMINAL OF CT CONVENTIONALLY TOWARDS TRANSFORMER

3.4.3

BUCHHOLTZ RELAY

3.4.3.1 Data: 1) Works on principal of BUOYANCY of liquid. 2) Position on pipe bent tank and conservator 3) Angle of inclination of pipe with horizontal 5 to 10 4) Length of straight run pipe section (I) Transformer to relay = 5D (min) (II) Relay to conservator = 3D ( min ) D : Dia of pipe 5) Vertical position of relay from tank = 8 cm ( min ) 6) Gas volume for Alarm operation

Trans. Size Upto 1 MVA 1 to 10 MVA 10MVA and above

7) Operating time 0.2 Sec

Pipe dia 2.5 cm 5 cm 7.5 cm

Setting range

Normal setting

100 - 120cc 185 - 250cc 220 - 280cc

110cc 220cc 250cc

8)

Diagnosis of Troubles from color of gas collected Colour Identification Colorless Air

Colour Grey

White /Milky

Black

Yellow

3.4.4

PRV

Gas of decomposed paper and cloth insulation Gas of decomposed wood insulation

Identification Gas of overheated oil due to burn of iron Gas of decomposed oil due to elect. Arc.

(PRESSURE RELEASE VALVE)

3.4.4.1 Data: 1 required / Universal for nitrogen cushioned transformer and optional for conservator type transformer 3.4.4.2 3.4.4.3 3.4.5

Data: 2 Alarm -0.32 kg/cm²/sec, Trip - 0.6 kg/cm²/sec Data: 3 Work on the principle of activation bellow due to pressure

3.4.5.1

OTI (OIL TEMP. INDICATOR)

3.4.5.2

DATA: 1 Work on the principle of volumetric change in bellow and corresponding conversion on scale due to temperature. DATA: 2 Temp. Rise above ambient ( TABLE) Type of winding

OA, OW OA / FA OA / FA / FOA FOA FOW 3.4.6

Top oil find temp rise on F.L condition 50ºC 50ºC 45ºC

Winding temp rise on F.L. condition 55ºC 55ºC 50ºC

WTI (WINDING TEMP. INDICATOR)

3.4.6 .1

DATA: 1 Bellow (Bourdon tube) and shunt network, being connected to WCT (Winding Ct), simulates the temp. Gradient, (proportionate with load current) and provides reading on the scale.

3.4.6.2 3.4.6.3

DATA: 2 Max. Heater coil current DATA: 3 Standard bellow heater

2 Amps = (2.5 ± 0.1)

at 30ºC

3.4.6.4 DATA :-4 TEMPERATURE Vrs CURRENT SIGNAL CHARACTRISTICS FOR RTD ( REMOTE THERMAL; DEVICE ) BS 1904 & DIN IEC 751 TEMP IN O C

RESISTANCE

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150

100.00 103.90 107.79 111.67 115.54 119.40 123.24 127.07 130.89 134.70 138.50 142.29 146.06 149.82 153.58 157.31

OUT PUT SIGNAL 0-5mA L0 Nom. Hi 0 0.050 0.283 0.333 0.383 0.617 0.667 0.717 0.950 1.000 1.050 1.283 1.333 1.383 1.617 1.667 1.717 1.950 2.000 2.050 2.283 2.333 2.383 2.617 2.667 2.717 2.950 3.000 3.050 3.283 3.333 3.383 3.617 3.667 3.717 3.950 4.000 4.050 4.283 4.333 4.383 4.617 4.667 4.717 4.950 5.000 5.050

OUT PUT SIGNAL 0-20mA L0 Nom. Hi 0 0.200 1.333 1.333 1.533 2.467 2.667 2.867 3.800 4.000 4.200 5.333 5.333 5.533 6.467 6.667 6.867 7.800 8.000 8.200 9.333 9.333 9.533 10.467 10.667 10.867 11.800 12.000 12.200 13.333 13.333 13.533 14.467 14.667 14.867 15.800 16.000 16.200 17.333 17.333 17.533 18.467 18.667 18.867 19.800 20.000 20.200

OUT PUT SIGNAL 4-20mA L0 Nom. Hi 3.800 4.000 4.200 4.867 5.067 5.267 5.933 6.133 6.333 7.000 7.200 7.400 8.067 8.267 8.467 9.133 9.333 9.533 10.200 10.400 10.600 11.267 11.467 11.667 12.333 12.533 12.333 13.400 13.600 13.800 14.467 14.667 14.867 15.573 15.733 15.933 16.600 16.800 17.000 17.667 17.867 18.067 18.733 18.933 19.133 19.800 20.000 20.200

3.5. BREAKER PROTECTION 1 Pole discrepancy Relay (PDR) 2. Local Breaker Back up relay (LBB) 3. 5.1

TIME CHART OF PDR: -

Breaker Close Operation

Pole Discrepancy

Normal Breaker Close Time

t

PDR Operation Time

Tripping Contact

Margin

T

t Mismatch allowable closing time between poles T It should be less than timing of unbalances current relay and zone 2 time of D.P. relay.

3. 5.2. TIME CHART OF LBB RELAY: (Fault Occurrence ) Normal Clearing Time (1 )

( 2)

(3)

Margin

Set time for Time Meas. Unit

(4)

(5)

Margin

Breaker Fail Relay Starts Total Clearing time of LBB Relay Maxim. Fault clearing time before system Instability

(1) (2) (3) (4) (5) 3.6.

BUS PROTECTION 1 2

3.7.

Protection Relay operation Time (Ex. DP Relay) Breaker Interruption Time Resetting Time Current Measuring Unit Trip Relay Time Back up Breaker Interruption Time

High impedance circulating current protection. Biased Differential circulating current protection.

LINE PROTECTION 1 2

Main Protection (Distance Protection) B/U Protection (O/C, E/F Protn.)

3.7.1 MAIN PROTECTION (DISTANCE PROTECTION) 3.7.1.1 STANDARD 3 ZONE PROTECTION 1st Method Zone 1 80% of protected line. * Zone 2 100% of protected line + 50% of shorted adjacent * * Zone 3 100% of protected line +100% of longest adjacent line. * Maximum zone 2 reach should be within the minimum effective Zone 1 reach of adjacent line. ** Maximum effective Zone 3 reach should cover the second section of line.

2nd. Method For available of the following data zone selection standard should be as follows a3 = 0.85 ( a + k b2) a2 = 0.85 ( a + k b1) a1 = 0.85 a

b1

a

b2

A NOTE

B

C

3. 7.1.2

Z1 :- a1 = 0.85 a ( Zone 1 ), Z2 :- a2 = 0.85 ( a + k b1 ) Z3 :- A3 = 0.85 ( a + k b2) = Zone 3 k = ( IA + IB ) / IA , Where IA = Service current on Station A IB = Service current on Station B TIME STANDARD Accepted fault clearance timing of EHV line. System Time 400 kV 80 ms

220 kV 132 kV

100 ms 150 ms

Selection of DP Relay Time

Zone Zone 1

Zone 2 Zone 3 Reverse Zone

Time Instant Relay operation time ( 30 to 40 mS ) 0.2 to 0.5 S 0.4 to 1 S 1 to 2 S

3.7.1.3 MINIMUM DE- ENERGISATION TIME ( FOR 3 PHASE DISCONNECTION ON TRANSMISSIOM LINE) Line KV

66 110 132

Minimum DeEnergisation Time in Sec. 0.1 0.15 0.17

Line KV

Minimum DeEnergisation Time in Sec.

220 275 400

0.28 0.3 0.5

3.7.1.4 FAULT, VOLTAGE AND CURRENT INVOLVEMENT IN TRANSMISSION LINE

Phase - Earth Fault Phase - Phase Fault Voltage Current Fault Voltage Current Fault Va Ia + 3KIo a-g Vab Ia - Ib a-b Vb Ib + 3KIo b-g Vbc Ib - Ic b-c Vc Ic + 3KIo c-g Vca Ic - Ia c-a Where K = Zero seq. compensation - factor = (Z0 – Z1) /3Z1 Zo - Zero Seq. impendance Z1 - +ve - Seq. impendance Io = Zero Seq. current 3. 7.1.5 ARC - RESISTANCE FORMULA (A.R. VAN C. WARRING TON) 1st Method: Ra = 28707 (L + ut) / I 1.4 L = Length of arc (Length of Insulator String) in mtr. U = Wind velocity in Km/hr I = Actual fault current in Amp. 2nd Method: Ra = (440 x Arc length in feet) Fault current 3. 7.1.6

DATA ON ARC ON THE TRANSMISSION LINE

Arc Resistance of Line

Line Voltage in KV 33 132 220 400

Length Ra (Arc In Mtr Resistance) Ohm 1.22 3.66 6.7 8.3

2.5 8.6 12.8 18

Sec. Voltage due to Arc for 220 KV Line, Arc Distance 1.12mtr and PTR 2000 Fault Sec. Voltage Current in mV in KAmp. 40 221 20 292 10 386 5 509 2 735 1 970

3. 7.1.7

TYPE OF D.P. RELAY I Impedance ii Reactance iii Mho or Admittance iv Ohm v Offset mho vi Modified impedance vii Elliptical viii Quadrilateral ix parallelogram

3. 7.1.8

D.P RELAY SETTING CALCULATION Data – Assumed line parameter data

3.7.1.8.1

Line Voltage

132kv Panther 220kv Zebra 400kv Twin Moose

R ohm/ ph/km 0.151 0.078 0.031

X ohm/ ph/km 0.401 0.402 0.327

Yc µ mho/ph/km 1.43 1.44 1.73

Formulae for parameter calculation

3.7.1.8.2 1

2

3

#R1 = l /a ohm/ph/km # R1 -+ve Sequence Resistance (Usually given in conductor data) X1 = 2 f x 2 x 10 –4 ln (Dm / Ds) ohm /ph/km X1 = +ve seq. reactance Dm = Mutual Geometric Mean Distance = (Dmab x Dmbc x Dmca) 1/ 3 Dmab = Mutual GMD between 'A' and 'B' conductor of the Line Dmbc = conductor between 'B' and 'C' Dmca = Between 'C' and 'A' conductors Ds = Self GMD Note: - For Double circuit loop reactance = 2 X 1 Ro = Zero sequence resistance = ( R1+ 0.00477f /1.609) ohm/ph/km

4. Xo = Zero seq. reactance Ohm/ph/km = (0. 01397 f /1.609) x log 10 De / (GMR conductor x GMD 2 sep) 1 / 3 ohm/ph/km De = Equivalent depth return in mtr = 658 x ( / f) = Earth Resistivity in ohm-mtr GMR conductor = Self radius = 0.7788 r GMD sep = (Dab x Dbcx Dca) 1/ 3 Dab= Distance Between A & B Conductor , Dbc = Between B & C, Dca=Between C & A 5.Rom = Zero seq mutual resistance Rom = 0.00477f ohm/ph/km 1.609 6. Xom = Zero seq. mutual reactance = ( 0. 01397 f /1.609 ) x log 10 (De / GMD eq ) ohm /ph/km (GMD)eq = ninth root of products of all nine possible distance between two circuit 3.7.1.8.3

Minimum Load Impedance (Z L )

Z L =(U² / MVA) Where U = Line to Line voltage, MVA = Maximum permitted load = (Umin. / 3 I max.) 3.7.1.8.4 Conversion to secondary value Z Sec = Z pri x C.T.R P.T.R Base = P.U x KV² impedance value 100 3.7.1.8.5 Zero seq. compensation factor (KN) i. KN = (Zo – Z1) / 3Z1, When mutual zero seq. impedance is not considered. = (Xo – X1 ) / 3X1 , ii. K 0 angle = Tan-¹ (Xo - X1) / (Ro - R1) --Tan-¹ (X1) / R1 iii. KNP = (Xo +Xom - X1 ) / 3X1 ,

When parallel system in normal operation

iv. KNG = (Xo² - X²om - XoX1 ) / 3XoX1 For parallel system is out of service and grounded at both ends.

3.7.1.9 POSSIBLE LENGTH OF LINE AND OPTIMUM POWER TO BE TRANSMITTED. Possible optimum power transmission Line voltage Line loading KW KV KM 11 24x10³ 33 200x10³ 66 600x10³ 110 11x10 6 132 20x10 6 166 35x10 6 230 90x10 6

3.7.1.10

Possible length in KM Length Line Minimum Max. 40 120 50 140 50 160 80 180 100 300

SUITABILITY OF RELAY PERFORMANCE

3.7.1.10.1 1st Method: Minimum voltage at relay: S.I.R: - System Impedance Ratio = Source Impedance Relay setting impedance C.I.R: -Characteristics Impedance Ratio = Maximum value of system impedance ratio =E-V V E - P.T. Secondary voltage V - Minimum voltage at relay Zs =(KV² ) / (MVA) Fault/source = Source impedance IF = KV for 3Ø fault current 3 (Zs +ZL) ZL = Line Impedance Vrelay = E/ (1+Zs / ZL)

3.7.1.10.2

2nd Method: -

ii. Ph - Ph fault Vrelay = ( 3 ZL x I F) / PTR OR VT Ratio ii.

Ph - Earth fault Vrelay = (IF x Zre) / VT ratio Zre - Earth loop impedance = ZL1 (1 + (K-1)/3) Where K = ZLo / ZL1, ZLo = Zero sequence impedance, ZL1 = +re sequence impedance

3.7.1.11

SELECTION OF POWER SWING BLOCK

1

(Block Z1 = OFF), (Block Z2 Z3 = ON)

2 During PS 3.7.2

( Z/

t)

Slow

O/C AND E/F PROTECTION 1 Non-Dir B/U Protection , 2 Directional B/U Protection

3.7.2.1

TYPE

(a) Definite Time relay (b) Inverse Definite Minimum Time Lag Relay (IDMTL) (i) Normal Inverse (NI) (ii) Very Inverse (VI) (iii) Extremely Inverse (EI) (iv) Long time Inverse (LTI) 3. 7.2.2 OPERATING CHARACTERISTICS (IDMTL RELAY) (IEC 255-4 BS 142, 3.2) t = K x Tm ( I / Is) C -- 1

Where t =Operating time in Second I = Fault current in Amp. Is = start current = 1. 1 IB in Amp Tm = Time Multiplier

Value of 'K' and 'C' Type NI VI EI LTI

K 0.14 13.5 80 120

C 0.02 1.0 2.0 1.0

3. 7.2.3 ERRORS OF IDMTL RELAY (AS PER BS 142 LIMITS)

Operating current (Multiple of plug setting) 2 5 10 20

Any PS and 1.0 time setting % Sec ± 24.15 ± 15.98 ± 15.08 ± 15.00

± 2.42

± 16.65

± 1.67

± 0.69

± 8.48

± 0.36

± 0.45

± 7.58

± 0.23

± 0.33

± 7.5

± 0.17

3. 7.2.4 O/C + E/F RELAY HIGH SET SETTING 3. 7.2.4.1 Max. 3Ø Short circuit current (i) (At beginning of line) I max = U / 3 Zs, (ii) (AT end) I max = U / 3 (Zs+ZL) (iii) (Source impedance) = Zs = KV² / MV A 3. 7.2.4.2 Minimum setting of relay Imin = 1.3 Imax Safety factor 1.2 Irelay = 1.2 Imin 3. 7.2.4.3 O/C Highest Relay setting = (Irelay) / CTR 3. 7.2.4.4 E/F High set =O/C High set 3

100% Plug setting and 1.0 time setting % Sec

3. 7.2.5

DIRECTIONAL B/U RELAY (O/C) Relationship between MTA (Maximum Torque Angle) and relay connection of O/C relay

Relay connecti on angle 30º 60º Type 1 60º Type 2 90º 90º

MTA

Connection Bph Cph Current Voltage Current Voltage coil coil coil coil Ib Vba Ic Vcb Ibc Vba Ica Vcb

Aph Current Voltage coil coil Ia Vac Iab Vac

0º 0º 0º

Ia

- Vc

Ib

- Va

Ic

- Vb

30º Lead 45º Lead

Ia Ia

Vbc Vbc

Ib Ib

Vca Vca

Ic Ic

Vab Vab

3.7.2.6 DIRECTIONAL B/U RELAY (E/F)

Relay characteristic angle 12.5º (lag) 14º (lag) 45º (lag) 60º (lag)

Connection Current coil Voltage coil Residual Current I0 = IA + IB + IC

Residual Voltage = Open Delta Secondary Voltage

3.7.2.7 CONTACTS, TERMINALS FOR OTHER RELAYS OF GEC ALSTOM MAKE

Sl No

Model

Standard

1

MVAA23

Two unit/Case

2

MCAG34

THREE/Case

3

MCAG14

Single unit/Case

CONTACTS Alar Trip m 2315-17 25 1-3 9-11 2-4 1-3

2-4

1-3

Current Terminal

23-24, 25-26,2728 # 27-28

Voltage Termin al 13-14 27-28

Aux. DC 220-250V

# 24-26-28 SHOTRTE D

4

MCGG22

5

MCGG62

6

MBCH12

7

MVAP22

8

MCVG62

25-23-21

9

MWTU11

27-28

10

MCND04

11 12 13

MYTU04 MVTU12 MCSU

Single unit/Case THREE/Case

Single Unit/Case

6-7 8-10 3637 3335 9-11

1-2 15-16 29-30 41-42

1-3 2-4

7-9 1820 7-9 4-16 4-6

27-28

13-14

21-22 23-24, 2526 #

13- 14 # 22-24-26 SHORTED

23-25-27 23-2527 Short 37&42, 41&46, 38&45 25-2321 13-14

6-8

13-14 27-28

1-3

27-28

13-14

3. 7.2.8 CONTACTS, TERMINALS FOR B/U RELAYS OF DIFF. MANUFACTURERS Make

Type

ER

IDMT NONDIR TJM10, 2TJM10, TJM20, TJM11, 2TJM10, TJM21

ER

IDMT DIR. TJM12, 2TJM12, TJM22

Standard

Single unit/Case Multi unit/Case 3O/C Multi unit/Case 2O/C, E/F Single unit/Case O/C Single unit/Case E/F

Alar Trip Current m Terminal Nor Inst mal ant 1,2 3,4 11,1 9,10 2 1,2 3,4 11,1 (5,6-R), (7,82 Y), (9,10-B) 1,2 3,4 11,1 (5,6-R), (7,82 E/F), (9,10-B)

Volt age

Aux. DC

-

5,6

-

-

1,2

3,4

11,1 2

9,10

5,6

-

1,2

3,4

11,1 2

9,10

5,6

-

3,4

-

9,10

-

IDMT NONDIR E/F TYPE TJM60

Single unit/Case E/F

1,2

ER

ER

IDMTL PROGRAMME Multi DCD, MIT unit/Case

1,2

3,4

3,4

-

IDMT NONDIR CDG11, 12,13,14 IDMT NONDIR CDG31, 32,33,34 CDG61, 62

Single unit/Case

1,2

3,4

3,6

(5,6-R), ( 7,8-Y),(9,10B), (11,12-E/F) 9,10

Multi unit/Case 3O/C Multi unit/Case 2O/C, E/F Single unit/Case

1,2

3,4

-

3,12 OR20

1,2

3,4

(5,6-R),( 7,8Y), (9,10-B) (5,6-R), (7,8E/F), (9,10-B)

-

1,2

3,4

9,10

7,8

3, 12 OR20 3,6 OR 20

1,2

3,4

3,17

(5,6-R), (7,8E/F), (9,10-B)

-

19,20 30V DC

1,2

-

3,4

9,10

-

-

11,1 2

13,1 4

-

-

20,19

9,10

-

-

1,2

5,6

11,1 2 7,8

(1,2-R),( 3,4 Y), (5,6-B), (7,8E/F) 7,8

-

1,2

-

3,4

9,10

1,2

-

7,8

-

1,4

EE ALSTOM

EE ALSTOM

EE ALSTOM

EE ALSTOM EE ALSTOM JVS

JYOTI ABB UE

IDMT DIR CDD 21, 23, 24,26 CDD 31,33,34,36 DEF. TIME Multi DELAY element/C CTU32 ase INSTANT Single CAG11, unit/Case 12,13,14, 17, 19 IDMT NONMulti DIR element/C JRC053 ase IDMT NONDIR IDMT NONDIR ICM21P IDMT NONDIR R-1156

Single unit/Case Single unit/Case Single unit/Case

-

3,8

ER

4C21

B 10

r 9

9

9

7

6

13

3

6

13

17,18 3,4

6 1 4

7 18

8 10

3 4 11 15

5 7

1+1 4+4 11+11 During Test both HT & LT Terminals to be shorted (Ex. 1+1) 12 13 14 12 16 8

1,2

3,4

7

17

27

10 20

30

8 or 9 Short (8 +9)

Single unit / Case Multi unit / Case Single unit / Case

1,2

3,4

10

10

5

5

1,2

3,4

1 0 5

18

13

10 20

9, 11

1,3

2 5

25

25

-do-

9,11

1,3

2 5

25

25

RADSB DTH31

-do-do-

15, 16 1,2

DTH32

-do-

DDT

3,4

Module 2 (RL1, RL2) General Command

DDT MBCH 12 (2 Winding MBCH 13 (3 Winding

y

b

R0

Y0

Aux. Volt DC

Trip

Alarm

Y 10

1,2

EE ALS TOM

EE ALS TOM

CURRENT TERMINALS LT Side Operating Point (BIAS)

HT Side (COMMON) R 1 0 3

Single unit / Case Multi unit / Case

DUO-BIAS M

ABB

Standard

Type

Make

3.7.2.9 CONTACTS, TERMINALS FOR DIFFERATIONAL RELAYS.

7

B0 7

28 or 29 Short (28 +29)

7

18 or 19 Short (18 + 19) 7

11

6

16

14

23 23

23

27 27 Short (24 +26 +28)

27

23 23 or or 21 21

23 or 21

27

27

5

27

7

220 V DC

1,2 5- 110 V 6- 220 V 19- 30V 20 - --ve 11- 30 V 13- 110 V 15–220 V 12 - - ve 3- + ve 8 --- ve 3- + ve 8 --- ve 13- + ve 14 -- ve 220 V 13- + ve 14 --- ve 220 V

4. DAT A ON ELECTRICAL SYSTEM EQUIPMENTS 4.1 BREAKERS Sl.no 1 2

Particulars

TECHNICAL PARTICULARS 33KV 132KV 220KV

System voltage (kv) System frequency (H2) Quenching medium

Vacuum, Oil

Operating medium

Spring

3

4 5

36 50

145 50 Oil, Air blast SF6 Spring Hydraulic Air pressure

400KV

245 50

420 50

Oil, Air blast SF6 (puffer)

SF6 (Puffer) Air blast

Spring Hydraulic Air pressure

Air Pressure

Insulation standard

(a) Lightning Impulse voltage (KVp) (1.2/50µ) (b) Power frequency withstand voltage (kv) 1min/50Hz) ( c) Minimum disruptive voltage (kV) 6 Normal current (A) Short time current withstand 7 capacity (KA)(3 sec) Fault Rating (i) Making capacity (KA) (ii) Breaking capacity (KA) 8 (iii) Breaking current out of ph (KA) (iv) Rated time charging current (A) (v) Over voltage factor for switching 9 Operating Sequence (a) Normal (b) Auto Reclose TRV (Transient Recovery Voltage) First phase to clear 10 factor Breaker operating time (i) Maxm break time (Open) ms (ii) Maxm Close time (ms) 11 (iii) Maxm Close -Open time (ms) (iv) Maxm time open interval between 1st and last phase (ms) (v) Maxm time close interval between poles.

170

650

1050

1425

70

275

460

520

28 1250

105 1250/1600

176 2000

320 2000/3150

25

40

40

40

70 25

100 40

100 40

100 40

6.5

10

10

10

50

50

125

400

3.0

3.0

3.0

3.0

O-10s-CO-3min-CO O-0.3s-CO-3min-CO

1.5

1.5

1.3

1.3

60 100

50 150

50 150

40 120

-

80

80

60

5

3.3

3.3

3.3

5

2

1

1

4.2 CIRCUIT BREAKER 4.2.1 132 KV SF6 GAS CIRCUIT BEAKER Particulars

Rating / Value Make Rated Lightening 650 KVp impulse with Stand voltage Type Rated short 31.5 KA Circuit Breaking Current Rated Voltage 145 KV Rated Operating 15.5 pressure KG/cm2 g Rated Frequency 50 HZ First pole to 1.5 Clear factor Rated Normal 3150 A Rated Duration 31.5 KA Current of short Circuit 3 Sec current Rated Closing 220 V DC Rated Line 50 A Voltage Charging Breaking Current Rated SF6 Gas pressure Rated Opening 220V DC Rated Voltage 415 VAC Voltage and frequency 50 HZ for Aux. Circuit GAS 6.0 bar at 20 Rated operating 0-0.3SPRESSURE SF6 0 c Sequence CO3Min-CO Total weight 2000 KG Gas weight 9 KG with Gas Sl. No. 11583C STD. IEC 56 Month / Year of MARCH./ Manufacturing 99 4..2.2

Rating / Value Crompton Greaves Ltd. Nasik 120-SFM-32 A

Particulars

220 KV SF6 GAS CIRCUIT BEAKER Particulars Rating / Particulars Value Make ABB Rated Lightening Limited impulse with Stand voltage Type ELF SL 4- Rated short 1 Circuit Breaking Current Rated Voltage 245 KV Rated Air

Rating / Value 1050 KVp 40 KA

21..5

pressure

4. 2.3

Rated Frequency

50 HZ

First pole to Clear factor Rated Duration of short Circuit current Rated Line Charging Breaking Current Rated SF6 pressure Rated Voltage and frequency for Aux. Circuit

Rated Normal Current

2000 A

Rated Closing Voltage

220 V DC

Rated Opening Voltage

220V DC

GAS PRESSURE SF6

7.0 bar at 20 0 c

Rated operating Sequence

Total weight with Gas Month / Year of Mang

3800 KG

Sl. No.

KG/cm2 g 1.3 40 KA 3 Sec 125 A

1-PH (230V & 3 PH 415 VAC 50 HZ 0-0.3SCO3Min-CO 307786

MARCH./ 99

33 KV VACUUK CIRCUIT BREKER Particulars Make

Rating / Value BHEL

Type

PVN 36

Rated Voltage

36 KV

Rated Frequency 50 HZ Rated Normal Current

1250 A

Shunt Trip coil

220 V DC

Spring REL. Coil Rated operating Sequence Sl. No.

220 V DC 0.3 Min. CO 9087652

Particulars impulse with Stand voltage Short Time Current Rated Air pressure Making Capacity Sym. Breaking Capacity with Dur. P.F With stand V Spec. Month / Year of Manufacturing TOTAL WEIGHT

Rating / Value 170 KVp 25 KA

62.5 KAp 25 KA for 3 Sec 70 KV IS 2156/ IEC 56 April/1991 1000 KG

4.2.

CURRENT TRANSFORMER 4.2.1. SPECIFICATIONS

RATIO OF THE CT

NUMBER OF CORES

RATED BURDEN AND FACTORS

CLASS OF ACCURACY

Items

CT Rating

No Of Cores

Core

Burden ( VA)

Factors

Core

Acc. Class

33 KV

3 Cores (Metering, Protection , Diff.) 5 Cores Metering Protection , Differenti al Bus Prot., Dist. Prot.

Meterin g

2.5,5, 7.5,10, 15,30

ISF (5, 10, 20)

METE RING

0.1, 0.2 0.5, 1, 3, 5

PROTE C TION

(5P, 10P 15P) *

Ratio

Primary Current

Secondary Current

33 KV In door Single Ratio

33 KV Out Door Multi Ratio

Suitably (10,15,20,30 50,75) Multiple or Fraction

1A or 5 A

66 KV

Protecti on

ALF (5,10,15,20, 30) Voltage 2.5,5, Across CT 7.5,10, = 15,30 (Burden X ALF)/ Rated Current Rated Short time Current Ist = 150 Ip for 1 Sec.

SELE TIVE PROTE CTION

PS * *

NOTES OF THE TABLE (4.2.1 ) ON THE NEXT PAGE. * Accuracy class is usually followed by ALF (5P10, 5P15, etc.) ** For accuracy Min. Knee Point Voltage (VK) and permissible Mag. Current (I mag) to be considered NOTE 1: -VK = K Is (Rct + Rb), K= Parameter depends upon System fault level and characteristics of the Relay Is = Sec. Reflected current Rct = CT Sec. Resistance at 75 0 C Rb = Resistance of Sec. Circuit with Lead NOTE 2: - Imag = P mA at V K / FM, Imag = Max Allowable Mag. Current (mA) P mA = Permissible Magnetizing Current ( m A ) Factor to be chosen 2 or 4, depending upon the application.

4.2.2

VOLTAGE CLASS AND INSULATION LEVEL

Nominal Highest Lightning Nominal Highest Power Lightning Power System System Frequency Impulse System System Frequency Impulse Voltage Voltage Withstand Withstand Voltage Voltage Withstand Withstand Voltage Voltage KV Voltage Voltage KV KV KV (RMS RMS RMS KV RMS KV (RMS) KV RMS KV PEAK PEAK List List 220 245 360 850 1 2 Upto 0.6 0.66 3 395 950 3.3 3.6 10 20 40 460 1050 6.6 7.2 20 40 60 400 420 950 * 1175 11 12 28 60 75 1050 * 1300 33 36 70 145 170 1050* 1425 66 72.5 140 325 325 525 524 1050* 1425 110 123 185 450 1175* 1550 230 550 * Switching Impulse Withstand Voltage in KV (PEAK) 132 145 230 550 275 650 4.2.3

ERRORS IN CT

4.2.3.1

METERING CORE Acc. Class

0.1 0.2 0.5 1.0 0.2s 0.5s

± % Current Ratio Error at % Of Rated Current

± Phase Angle displacement Error in Minutes at % of Rated Current 1% 5% 20% 100% 120% 1% 5% 20% 100% 120% 0.4 0.2 0.1 0.1 15 8 5 5 0.75 0.35 0.2 0.2 30 15 10 10 1.5 0.75 0.5 0.5 90 45 30 30 3.0 1.0 1.0 0.75 0.35 0.2 0.2 0.2 30 15 10 10 10 1.5 0.75 0.5 0.5 0.5 90 45 30 30 30

4.2.3.2 PROTECTION CORE Acc. Class

5P 10P 15P

Current Error at Rated Primary Current (%) ±1 ±3 ±5

Phase displacement at Rated Primary Current (Minutes) ± 60 -

Composite Error at Rated Acc. Primary Current (%) 5 10 15

4.2.4 RELAY DETAIL FOR SELECTION OF INSTRUMENT TRANSFORMERS 4.2.4.1 TRANSFORMERS DIFFERENTIALS 4.2.4.1.1. 1

ALSTOM MAKE Relay type:DTH 31/32

V k >40*I (R CT +2R L );Example: V k >40(1)(3+4) >280V 2.

Relay type: MBCH 12/13

V k >24 In (R CT +2R L ) Where V k =Knee Point Voltage In=Relay rated current, R L =Total Lead Resistance Ie=30(R CT +2R L +Rre) In , >30(4+4+3)1, >330V Note: Over current factor of 30 recommended Excitation Current -Not applicable* 2.

Relay type:SPAD346C (Stabilised diff. Relay)

V K >4xI max x (R in +R L )/n, Where, n =Transformation ratio of CT>(R CT +R L +0.5/sq.of Isn) Rin =Sec. Resistance of CT 2R L =Control cable (‘To &fro ’)resistance Imax =Id/In>>set on relay (Range available 5 to 30, default set is 10)

15In

3.

Relay type:RET316 (Stabilised diff. Relay)

n ’ ==n (Pr +Pe) / (Pb +Pe), Where, n =ALF n ’ ==Effective over current factor, is a function of fault current I k ,freq and time constant of network, and read from graph in RET manual Pb =connected burden at rated current, Pe =CT losses of sec windings Pr =rated CT burden, DC time constant assumed is 300msec *Not Applicable :-Relay provided with ‘ Magnetizing Inrush Restraint ’ based on Second Har monic Content of the inrush current and hence ‘Imag ’ calculation is not applicable... 4. 2.4.1.3. 1.

EASUN REROLLE Relay type:4C21 (Static)(Low impedance)

CT Class :PS, V K >2I f (R CT +R L +Rict (P))+(ICT V K x ICT ratio) Example: V K >2 x 10.9375 (2+3+1)+(14.43/ 0.875) x 0.577 >140.75 Volts R CT -Main CT resistance, Rict (P)-ICT primary winding resistance R L -Lead resistance, I f -Max. thro fault current 2.

Relay type: Duobias M(Numeric), (Differential and Restricted Earth Fault)

V K >4xI(A+C), Where : I =Either max 3-phase through fault current referred to secondary (as limited by transformer impedance)or high-set setting, whichever is greater. A =Sec. winding resistance of each star connected CT C =CT secondary loop resistance for internal faults. CT Class recommended-PS,X to BS 3938,TPS to IEC-444. 2.4.2 GENERATOR DIFFERENTIAL PROTECTION 4. 2.4.2.1. 1.

ALSTOM Relay type:CAG34 (High Impedance Scheme)

V K >2I f (R CT +2R L ) Example :V K >2x10(3+4) >140V Where ,I f =sec. equivalent of Fault Current Ie =Is-Ir =(0.15-0.10) /2 =25 m A at V K /2 2.

Relay type: LGPG, MiCOM 340 (Numerical)

For voltage dependent, over current , field failure and negative phase, sequence protection V K >20In (R CT +2R L ) l For stator earth fault protection V K >Is (R CT +2R L +RR) 2.For generator differential protection: Low impedance diff. V K >50In (R CT +2R L ) High impedance diff V K >2 Vs where Vs =1.5I f (R CT +2R L ), Rs =Vs/Is

3.Relay type:YTGM15,YCG15AA,ZTO11(Generator Backup) V K >2If (R CT +2R L +M+CM), Where CM=connected burden 4. 2.4.2.2. 1.

ABB Relay type: RADHA /RADHD (High impedance )

V K >2I K (R CT +R L ), >2x25(4+3), >350V, R L in case of generator is longer i.e.2R L =6 Ohms I K will be higher considering Xd ”(0.2 pu)and CT sec.of 5A Excitation current -Not applicable * Excitation current is kept low for increasing the primary sensitivity *Not Applicable :-Relay provided with ‘ Magnetizing Inrush Restraint ’ based on Second Har monic Content of the inrush current and hence ‘Imag ’ calculation is not applicable... 4. 2.4.2.3. 1.

EASUN REYROLLE Relay type:4B3 (EM)/DAD 3 (Static)/Argus-1 (Numeric)(High Impedance Scheme)

V K >2I f (R CT +2R L ), Example: V K >2x10(3+4) >140 Volts CT Class :PS, I f -Max. thro fault current, R CT -Main CT resistance R L -Lead resistance between CT to relay. 2. Relay type: GAMMA (Numeric) (High Impedance) For Two off 3 phase Inputs (Line end and Neutral end)and for Neutral Earthed CTs. In case of low impedance bias diff functionsa)V K >50xIn(R CT +2R L +RR) where max. through fault current=10xIn with max X/R=120. b)V K >30xIn(R CT +2R L +RR) where max. through fault current=10xIn with max. X/R =60 In=Rated Current Sec. X/R=X/R ratio for max. through fault condition. R CT =Sec. resistance of CT, R L =Lead resistance between CT and Relay RR=Resistance of any other protection functions sharing the CT 4.2.4.3 BUS DIFFERENTIAL PROTECTION 4.2.4.3.1. 1.

ABB Relay type: RADHA/RADHD (High impedance scheme)

V K >2I K (R CT +R L ) , >2x40 (4+4) , >640 V 2. Relay type: RADSS (Medium impedance scheme) Depending on diff. ratios , For 1A CT, Vk shall be 500V.

Excitation Current -Not applicable* *Not Applicable :-Relay provided with ‘ Magnetizing Inrush Restraint ’ based on Second Har monic Content of the inrush current and hence ‘Imag ’ calculation is not applicable... 4. 2.4.3.2. 1.

ALSTOM Relay type:CAG34 (High Impedance scheme)

V K >2I f (R CT +2R L ), Example: V K >2X10(3+4), >140V 2.

Relay type: DIFB –DIFBCL

V K >K x In(RTCP+R F +Rd/n 2 ), Where: K=(1.2/40)x(I CC /I N ) I N =Main CT primary rated current, I CC =Max short-circuit current delivered to bus bar via the input Where MCT is installed. RTCP=Rest. of secondary of MCT, R F =Rest. of link loop between MCT and auxiliary CT, n=Ratio of auxiliary CT , Rd/n 2 =Value of differential resistance transposed to ACT primary 3.

Relay type: MCTI 34 (Numerical)

V K >1.6V S , V S =1.25xI f (R CT +2R L ) Where: R CT =CT resistance, RL=Max lead resistance from CT to common point, I f =Max internal secondary fault current. 4.2.4.3.3. 1.

EASUN REROLLE Relay type:B3 (EM)/DAD3 (Static)

CT Class: PS , V K >2I f (R CT +R L ) Example: V K >2X10(3+4) >140V I f -Max. thro fault current R CT -Main CT resistance R L -Lead resistance between CT to relay

4. 2.4.4

DISTANCE PROTECTION

4. 2.4.4.1.

EASUN REYROLLE

1.

Relay type: THR (Static)

CT Class :PS, V K >Ix(R L +R 2 +X/Rx(R 3 +R 2 )) Example: V K >10(3.8+7+4(1.2+7)) >436V Where: R L -Burden of relay (3.8 Ohm max.) R 2 -Resistance of leads plus resistance of CT sec. X/R-Ratio of reactance to resistance of the system for fault at the end of zone 1 , R 3 -constant depending on impedance setting of zone 1. (1.2 Ohm max.) I-Sec. fault current for fault at end of zone 1 Note: X/R =4 for 132 kV system in above. =7 for 220 kV =11 for 400 kV 2 Relay type: Ohmega (Numeric) V K should be equal or greater than the higher of following two expressions. a)V K >K x(I P /N(1+X P /R P ))x(0.03+R CT +R L ) For phase-phase faults b)V K >K x(Ie /N(1+Xe/Re))x(0.06+R CT +R L ) For phase-earth faults I P -Phase fault current calculated for X P /R P ratio at the end of zone 1 Ie -earth fault current calculated for Xe /Re ratio at the end of zone 1 N -CT ratio., X P /R P -power system reactance to resistance ratio for the total plant including the feeder line parameters calculated for phase fault at the end of zone 1 Xe /Re -similar ratio to above but calculated for an earth fault at the end of zone 1 R CT -CT resistance, R L -lead burden CT to Relay K -Factor chosen to ensure adequate operating speed which is >1.0 4. 2.4.4.2

ALSTOM

1. Relay type: Micromho, Quadrmaho V K >I f (X/R)(M+R CT +nR L ) Example: V K >10(4)(10.2+3+4) >40(17.2) >688V Ie (Ik x Isn/ Ipn )x a x (R CT +R L +0.5/(Isn/Ipn)2 ) Where a =factor for the DC time constant (approx 10 for about 100msec) Excitation Current NxK1xIn(R CT +XR L ) Magnetizing current50xIn(2.2/In2+R CT +R L )-for star connected CTs. b. V K >50xIn/v3(9.7/In2+R CT +R L )-for delta connected CTs.

2.

Relay type: MiCOM P540 (Numerical)

V K >K *In (R CT +2R L ) Where: K is a constant depending on I f =The maximum value of through fault current for stability and is determined as follows: For relays set at Is1 =20%,Is2 =2 In,k1 =30%,k2 =150%: K =40 +(0.07 x (I f x X/R))and K =65 This is valid for (I f x X/R)150

ETHYLENE (C2H4) ACETYLENE (C2H2)

GERMANY

VDE – 0370

INDIA

IS 335

SWEDEN ITALY SWITZERL AND UK USSR IEC

SEN-14 A.E.1.7 S.E.V.124

>700

4.7.25 TYPICAL VALUE OF CAPACITANCE & TAN Voltage Rating 400/220 KV

220/132 KV

132/33 KV

132/11 KV

66/11 KV

33/11 KV

NATIONAL SPECIFICATIONS

BS 148 GOST-981 IEC: 296

OF TRANSFORMERS

Configuration Capacitance in nF Tan HV – LV 4 -5 0.002 HV - Tank 13 - 15 0.007 LV - Tank 23 - 24 0.004 HV – LV 5 -7 0.003 HV - Tank 10 - 12 0.005 LV - Tank 19 - 22 0.004 HV – LV 5 -7 0.003 HV - Tank 10 - 12 0.005 LV - Tank 19 - 22 0.004 HV – LV 5 -7 0.003 HV - Tank 10 - 12 0.005 LV - Tank 19 - 22 0.004 HV – LV 5 -6 0.003 HV - Tank 2.9 - 3.5 0.006 LV - Tank 6 - 10 0.005 HV – LV 8 - 10 0.015 HV - Tank 11 - 13 0.015 LV - Tank 15 - 17 0.015

- 0.005 - 0.009 - 0.008 - 0.006 - 0.010 - 0.010 - 0.006 - 0.010 - 0.010 - 0.006 - 0.010 - 0.010 - 0.006 - 0.008 - 0.008 - 0.018 - 0.020 - 0.020

4.7.26. DURATION OF OVER LOADING OF OIL – IMMERSED TRANSFORMER

Duration of Overload in Oil Temp. At the beginning of the Overload minutes in deg. Cent. For cooling method ONAN OFAN OFAF 10 20 30 40 50% ONAF OFW % % % % 50 55 49 160 80 60 30 15 75 68 60 120 60 30 15 8 90 78 68 60 30 15 8 4 Note _: - Type of Insulation: - A Class for above Table

Previous Continuous Loading as % Rated Load

4.7.27. PERMISSIBLE OVER LOADING CAPACITY TRANSFORMER Cooling air Temp. Deg.Cent.

All day LONG PERIOD MEDIUM PERIOD SHORT PERIOOD Heavy Load 16 Hrs Remaining Remaining 8 Hrs Remaining 3 Hrs Continuous Heavy 8 Hrs Light Heavy 16 Hrs Heavy Hrs Light Load) Load Load Load Light Load Load Load 0 120 125 105 130 105 150 105 5 115 120 100 125 100 145 100 10 110 115 94 120 94 140 94 15 105 110 88 115 88 135 88 20 100 105 82 110 82 130 82 25 94 100 76 105 76 125 76 30 88 94 70 100 70 120 70 35 82 88 64 94 64 115 64 40 76 82 57 88 57 110 57 45 70 76 49 82 49 105 49 50 64 70 40 76 40 100 40 Note: - Type of Cooling: - ON (Oil Natural) Type of insulation A Class. Max. Oil Temp. : - 80 Deg. Cents. Max. Winding Temp. : - 95 Deg. Cents. 4. 7.28 Daily Peak Loads per unit of Name plate rating to give Normal Life Expectancy (COOLING – SELF COOLED OR WATER COOLED ( OA OR OW ) $ Peak Load Time In Hrs 1/2 1 2 4 8 24

Cooling – Self Cooled or Water cooled ( OA or OW ) $ Continuous equivalent Load in %tage of rated KVA preceding the peak Load 50 percent 70 percent Ambient in degree C Ambient in degree C 0 2.00 2.00 1.76 1.54 1.41 1.33

10 2.00 1.88 1.64 1.43 1.30 1.22

20 2.00 1.73 1.51 1.33 1.19 1.11

30 1.89 1.58 1.37 1.19 1.08 1.00

40 1.70 1.41 1.22 1.06 0.96 0.89

50 1.52 1.23 1.00 0.94 0.84 0.78

0 2.00 1.95 1.72 1.52 1.40 1.33

10 2.00 1.80 1.59 1.41 1.30 1.22

20 1.95 1.65 1.46 1.29 1.19 1.11

30 1.78 1.49 1.32 1.17 1.07 1.00

40 1.60 1.32 1.16 1.04 0.95 0.89

50 1.41 1.14 0.99 0.89 0.83 0.78

90 percent Ambient in degree C 0 2.00 1.86 1.66 1.50 1.39 1.33

10 1.99 1.70 1.53 1.39 1.29 1.22

20 1.81 1.55 1.39 1.26 1.18 1.11

30 1.64 1.39 1.24 1.13 1.06 1.00

40 1.46 1.20 1.08 1.00 0.94 0.89

50 1.24 0.99 0.90 0.84 0.82 0.78

$ Subtract 5 0 C from each of the ambient column heading for water cooled transformer. Minimum water temp. must be above 0 0 C Example :- Assume a load cycle which resolves to a constant value of 50 % followed by a 100 % peak load for 2 Hrs. using the above table if the ambient Temp. is 30 0 C , a self cooled (OA ) , a water cooled ( OW ) transformer will carry 1.32 times name plate rating for 2 Hrs following an equivalent continuous load up to 70 % of name plate rating , if the equivalent 2 Hrs peak load from the load cycle is 10 MVA . The constant equivalent load before the peak is 5 MVA which is 66.6 % of the name plate rating of the transformer . Therefore a 7.5 MVA transformer is suitable for this daily load cycle. 4. 7.29 Daily Peak Loads per unit of Max . Name plate rating to give Normal Life Expectancy (COOLING – FORCED AIR COOLED RATED 133 % OR LESS OF SELF COOLED RATING OR WATER COOLED ( OA / FA ) Peak Load Time In Hrs 1/2 1 2 4 8 24

Cooling – Forced Air cooled Rated 133 % or less of Self Cooled Rating or Water cooled ( OA / FA ) Continuous equivalent Load in %tage of rated KVA preceding the peak Load 50 percent 70 percent 90 percent Ambient in degree C Ambient in degree C Ambient in degree C 0 2.00 1.90 1.64 1.46 1.37 1.31

10 2.00 1.77 1.53 1.36 1.27 1.21

20 1.97 1.64 1.42 1.26 1.17 1.11

30 1.82 1.50 1.29 1.15 1.07 1.00

40 1.66 1.35 1.16 1.03 0.96 0.89

50 1.49 1.19 1.02 0.90 0.84 0.78

0 2.00 1.84 1.61 1.45 1.37 1.31

10 2.00 1.71 1.50 1.35 1.27 1.21

20 1.89 1.57 1.38 1.24 1.17 1.11

30 1.74 1.43 1.26 1.13 1.07 1.00

40 1.58 1.28 1.12 1.01 0.96 0.89

50 1.40 1.11 0.97 0.88 0.83 0.78

0 2.00 1.77 1.58 1.44 1.36 1.31

10 1.92 1.63 1.46 1.34 1.27 1.21

20 1.77 1.49 1.34 1.23 1.17 1.11

30 1.61 1.35 1.21 1.11 1.06 1.00

40 1.43 1.19 1.08 1.00 0.95 0.89

50 1.25 1.00 0.91 0.85 0.83 0.78

Note:- The peak load in this table are calculated on the basis of all cooling in use during the period preceding the peak load. When operating with out fans, use this table for OA transformer 4. 7.30 Daily Peak Loads per unit of Max . Name plate rating to give Normal Life Expectancy (COOLING – FORCED AIR COOLED RATED 133 % OR LESS OF SELF COOLED RATING OR WATER COOLED ( OA / FA ) Peak Load Time In Hrs 1/2 1 12 4 8 24

Cooling – Forced Air cooled Rated 133 % or less of Self Cooled Rating or Water cooled ( OA / FA ) Continuous equivalent Load in %tage of rated KVA preceding the peak Load 50 percent 70 percent 90 percent Ambient in degree C Ambient in degree C Ambient in degree C 0 2.00 1.73 1.53 1.40 1.34 1.30

10 1.91 1.62 1.43 1.31 1.35 1.20

20 1.78 1.51 1.33 1.21 1.16 1.10

30 1.65 1.38 1.22 1.11 1.06 1.00

40 1.52 1.25 1.11 1.00 0.96 0.90

50 1.37 1.12 0.98 0.89 0.84 0.79

0 1.96 1.68 1.51 1.40 1.34 1.30

10 1.84 1.58 1.41 1.31 1.25 1.20

20 1.71 1.46 1.30 1.21 1.16 1.10

30 1.58 1.33 1.19 1.10 1.06 1.00

40 1.43 1.20 1.07 1.00 0.96 0.90

50 1.28 1.06 0.95 0.88 0.84 0.79

0 1.89 1.64 1.49 1.39 1.34 1.30

10 1.77 1.53 1.39 1.30 1.25 1.20

20 1.64 1.41 1.28 1.20 1.15 1.10

30 1.50 1.28 1.17 1.09 1.05 1.00

$ Subtract 5 0 C from each of the ambient column heading for water cooled transformer. Minimum water temp. must be above 0 0 C

40 1.35 1.15 1.06 0.99 0.95 0.90

50 1.19 1.01 0.93 0.87 0.84 0.79

4.7.31 PERCENT CHANGE IN KVA LOAD FOR EACH DEGREE CENTIGRADE CHANGE IN AVEARAGE AMBIENT TEMPERATURE Type of Cooling Self Cooled Water Cooled Forced Air Cooled Forced Oil Cooled

Air above 30 0 C average OR Water above 25 0 C - 1.5 % per degree - 1.5 % per degree - 1 % per degree

Air above 30 0 C average OR Water above 25 0 C 1 % per degree 1 % per degree 0.75 % per degree

- 1 % per degree

0.75% per degree

4.7.32 TOLERANCES TRANSFORMER ON COMPARISION BSS 171:1970 AND ISS 2026: 1926 Sl. Particulars BSS 171 ISS 2026 + 1/10 of Total Loss +10 % of the 1 Total Loss guaranteed Value + 1/7 of each component +10 % of the 2 Component losses, provided that the guaranteed Value Losses tolerance for the Total losses is not exceeded. 3 Voltage ratio ± 1/200 of declared ratio or Same as BSS % of the declared ratio at No Load equal to 1/10 of the actual on the % voltage at rated current Principal Tapping (Rated Voltage Ratio 4 Impedances Voltage (a) Principal Tapping Same as BSS i) Two ± 1/10 of the declared Winding Tfr impedance voltage for that tapping ± 1/10 of the declared ± 15 % ii) impedance voltage for Multi Winding Tfr specified pair of winding. ± 1/7 of the declared impedance voltage for the second specified pair of winding. ± 1/7 of the stated value b) For tapping other for each tapping within ± 5 % of Principal tapping than the declared impedance principal voltage for the second tapping specified pair of winding. + 3/10 of the declared No No tolerances 5 No Load load current Current

4. 7.33 OIL HANDLING PROCEDURE IN TRANSFORMER

4. 7.34

TYPICAL VALUE OF CAPACITANCE & TAN Voltage 400 KV 220 KV 132 KV 66 KV 36 KV

4. 7.35

Capacitance ( nF) 420 - 480 280 - 400 180 - 300 180 - 300 260 - 280

DGA for NORMAL BUSHING Oil.

OF BUSHINGS

Tan 0.002 - 0.005 0.002 - 0.005 0.002 - 0.005 0.002 - 0.004 0.002 - 0.004

As per IEC – 36 AWG3)

H2 = 100ppm, CH4 = 30 ppm, C2H2 = 2 ppm, C2H4 = 300 ppm, C2 H6 = 50 ppm, CO = 1000 ppm, CO2 = 3000 ppm

4.8

SQUIRREL CAGE INDUCTION MOTOR 4.8.1 DATA % Voltage dip = (Starting KVA X 100) / fault KVA at point of supply Size of Approx Size of PVC Starting KVA (Approx) for condition of starting motor current Aluminum D.O.L Star/delta Auto Transformer (400V, (Amp) at cable (mm2) 6 F.L current 2F.L current 1.5 F.L 1.35 F.L 50Hz) 0.8 P.F 5 H.P 8 2.5 33.25 10 H.P 15 4 62.35 20.78 15 H.P 22 10 91.44 30.48 20 H.P 29 16 120.54 40.18 30.14 25.11 30 H.P 42 25 174.58 58.19 43.65 36.37

4.8.2 CAPACITOR RATING (KVAR) FOR MOTORS Motor rating (KW) Capacitor rating (KVAR)

< 4 4 5.5 7.5 11 15 18.5 22 1

2 2.5 3

5

6

8

30 Approx 35% of 10 motor rating

4.8.3 CAPACITOR REQUIRED FOR DESIRED P.f Existing P.F 0.20 0.40 0.50 0.6 0.7 0.8 0.85 0.9 0.95

8.4.1

Capacitor in KVAR with 1 KW Active power, for below P.F 0.75 0.8 0.85 0.9 0.95 1.0 4.02 4.15 4.28 4.42 4.57 4.90 1.41 1.54 1.67 1.81 1.96 2.29 0.85 0.98 1.11 1.25 1.4 1.73 0.45 0.58 0.71 0.85 1.00 1.33 0.14 0.27 0.40 0.54 0.69 1.02 0.13 0.27 0.42 0.75 0.11 0.26 0.59 0.16 0.48 0.35

CAPACITOR REQUIRED FOR INDUCTION MOTORS IN KVAR (Orissa Gazette notification No. 23191-Com- VI – 3186 (Vol- II) Dt. 19.01.1988 MOTOR HP 3 5 7 10 15 20 25 30 40 50 60 75 100 125 150

750 RPM 1 2 3 4 6 8 9 10 14 16 20 24 30 39 45

1000 RPM 1 2 3 4 5 7 8 9 12 16 20 23 30 38 45

1500 RPM 1 2 3 4 5 6 7 8 11 13 16 19 24 31 36

3000 RPM 1 2 3 4 4 5 6 7 10 11 14 16 20 26 30

4.9.

BATTERY

4.9.1DATA Sl.No. 1 2 3 4 5. 6 7 8

9

DATA/PARTICULARS RECOMMENDED END VOLTAGE SP. GRAVITY (FULLY CHARGED) SP. GRAVITY (FULLY DISCHARGED) ALLOWABLE DIFF. IN MAX & MIN SP. GRAVITY NORMAL OPERATING VOLTAGE FULLY CHARGED VOLTAGE Equivalent SP. GRAVITY AT 27 0 C RATE OF CHARGING 1. FINISHING RATE AT 10 HRS 2. NORMAL RATE 3. EQUALISING CHARGE AT 10 HRS FLOAT CHARGE 1. FLOAT CHARGE CURRENT 2. TICKLE CHARGE CURRENT

VALUES 1.85/CELL 1200 AT 27 0 C 1190 AT 27 0 C 30 POINTS /CELL 2.15/CELL 2.4 –2.5 /CELL HYDROMETER READING AT t 0 C + 0.0007 ( t – 27 ) (% AH Rating of Battery) in Amp 4

10 2 (AH

2) /2400 + Sub Station Load

50 TO 100 mA / 100 AH Battery Capacity 2.15 to 2.17 V / Cell

3. SET Voltage

4.9.2

IMPORTANT NOTE

1. BATTERY SHOULD BE NORMALLY KEPT ON FLOAT CHARGE 2. EQULISING CHARGE 1. For FLOAT charge (2.16 to 2.2) / cell, equalizing charge to be given once in 3 months 2. For FLOAT charge (2.06 to 2.16) / cell, equalizing charge to be given once in a month for 220V Battery 3. BOOST CHARGE 1. Allow BOOST charge after Test Discharge 2. Allow BOOST charge for low sp. Gravity of major cells (below 1190) and low Voltage (Below 1.9 V 4. CONDITION CHARGE Discharge the battery to end voltage 1.85 V and again charging is called CONDITION CHARGING. It should be done once in a year.

4.9.3

MAINTENANCE SCHEDULE OF BATTERY

PERIODICITY

DAILY

WEEKLY

ITEMS TO BE CHECKED 1. Measure and record the pilot cell Voltage, Sp. Gravity & Electrolyte Temperature 2. Battery Voltage by Switching off Charger 3. Hourly reading DC Voltage, Charger out put current and Trickle Charge Current 1. Cleaning of terminals, topping up distilled water if required 2. Check pilot cell reading and adjust the trickle charge current if required

PERIODICITY

MONTHLY

YEARLY

ITEMS TO BE CHECKED 1. Sp. Gravity, Voltage of each cell and electrolyte Temp. 2. Give Equalizing Charge 3. Switch off Charger and test tripping/ closing of any one feeder from Battery Source 4. Check all connection of battery and Charger

1. Allow Condition Charging

4. 10

ENERGY METERS

4.10.1PERCENTAGE ERROR LIMITS (SINGLE PHASE METERS AND POLY PHASE METERS) 4.10.1.A. TABLE FOR ACC. CLASS (0.2,0.5,1.0,and 1.5) IEC 687: 1992 % Load P.F (Ib) (Cos ) 1.0 1 - “digital channel”

12. 3. Power Allocation to speech and VFT channel

AF Signal

Speech test tone 800 Hz Internal test tone 1000 Hz Speech with safety margin VFT channels and modems 50Bd 100Bd 200Bd 600Bd 1200Bd,V.23 1200Bd+speech 2400Bd Max. permissible load with speech plus superimposed channels Pilot tone

Signal levels

Absolute Voltage levels at the test sockets TXAF (-10dBr) dBmO Weighti dBu ng 0 1.0 -10

+3

1.41

-7

-14 -11 -8 -3 0 -3 0 +10.8

0.2 0.28 0.4 0.71 1.0 0.71 1.0 3.48

-24 -21 -18 -13 -10 -13 -10 +0.8

-6

0.5

-16

12.4 BASIC TERMS TO PLCC. TERMS Absolute power level(L) Absolute voltage level ((L u ) Relative level (Lrel )

FORMULA 10 log (Px)/1mW 20 log (Ux)/775mV

UNIT REFERENCE dBm P0 =1mW dBu U0 =775mV

Magnitude of diff. dBr Reference=0dBr w.r.t.vertual reference point(0dBr) Absolute signal Magnitude of diff. dBmo Reference=0dBr Level(L0) w.r.t.vertual reference point(0dBr) Conversion to another $ Lu= L ( dBm ) system impedance Lu 10 log ( 600 ohm / Z ohm ) $ Example = The power level at 75ohm RF O/P of a PLC equipment is given 40 dBm. Then the voltage level Lu would be = Lu= 40 ( dBm ) - 10 log ( 600 ohm / 75 ohm ) =31dBu

12. 5. Types of different Channel Channels Data PLCC 1.50-450K Hz frequency for Power sector 2.50- 150 K Hz freely available to Power Sector 3.Rest with permission of DOT ( Deptt. Of telecomm ) and WPC ( Wireless Planning Co-ordination . 4. 500 ± 5 K Hz used for International distress calling Microwave / 1. Power system net work with PCM ( pulse code modulation ) , multi VHF Radio Link channel digit circuits based on multiple of 30 channels PCM Multiplex operating at 2048 kpbs 2. The modulation method is either of Two level Frequency Shift Keying ( FSK ) or Four level 3. WPC has assigned 2.30 to 2.50 GHz and 8.3 to 8.5 GHz bands to Power Sectors for narrow band net work . Other frequency band is 7.11 to 7.125 GHz, 7.725 to 7.8 to 7.8 GHz & 10.5 to 10.68 GHz. Satellite Links SCPC technique is used with 64 kbps PCM or 32/16 kbps delta modulation or 9.6/ 16 K voice coding. Fibre Optics 1. Band with of 100 GHz per KM with repeater span of 50 Km is used with mono mode fibre 4 to 24 Cores as per CCITT Rec. G652 having 1300nm wave length with attenuation figure of 0.5 db per Km • 30 channels ( Primary Multiplex ) – 2 Mbps • 120 channels ( 2nd Order Multiplex ) – 8 Mbps • 480 channels ( 3rd order Multiplex ) – 34 Mbps • 1920 channels ( 4th order Multiplex) – 140Mbps

12.6 .Other Data related to TELECOMMUNICATION Sl No 1 2 3 4

5 6 7 8

9

10

Data

Value

Comm. Channel width 0-4 KHz Unused ( Vacant ) width 0-300 Hz ( To avoid 6th Harmonics ) Speech channel 300-2200 Hz Pilot frequency dialing 3600 ± 30 Hz purpose Centre frequency for healthy 3600 Hz ness test For VFT band 2200-3570 Hz Frequency Shift Keying (FSK) 50, 100, 200 baud as per CCITT recommendation DATA TRANSMISSION a. 1200 baud rate FSK to CCITT Rec.V23 on a basic 4wire, 4 KHz PLC b. 2400 baud phase modulated 4- wire leased telephone type circuit as CCITT Rec.V29 c. PCM 64 kbps digital data channel to CCITT Rec.C702 d. For FAX, CCITT Rec.T3 used with vestigial side band modulation ( BW 800- 2600 Hz LEASED CIRCUITS a. 2- Wire audio cables ( up to 20 Km ) b. CCITT M1 020 and M1 040 types of circuit ( Similar to PLC and Microwave System ) c. Wide Spectrum Signals on either group ( 60 to 108 KHz ) or super group ( 312 to 520 KHz ) as per CCITT Rec. M900 & M910 d. Satellite leased circuit such as SCPC, FM modulated, Analogous MIN. CLERANCES POWER a. LT Lines ( 230/400 V ) -- 1.22 m AND TELECOM LINE b. 11 KV Lines ---- 1.83 m c. 33/66 KV Lines ---- 2.44 m d. 132 KV Lines ---- 3.05 m e. 220 KV Lines ---- 4.58 m f. 400 KV Lines ---- 5.49 m 800 KV Lines ---- 7.94 m

12. 7. Channel specific data with variable centre frequencies ( MODEM)

Channel ( Bd ) Maximum Baudrate (Bits/s) Nominal Baudrate(Bits/s) ITU-T Channel Channel bandwidth / spacing Hz Lowest center frequency Hz Highest center frequency Hz Frequency shift Hz Maximum isochronous distortion: at nominal baudrate % at maximum baudrate % with receive level margin of dB Regenerator On Receive distortion % < 25 % < 50 % Channel delay times: Propagation delay ms Max RTS On to DCD On delay ms Max RTS Off to DCD Off delay ms RTS On to CTS On channel dependent delay a) ms TX channel turn-off time ms (for half-duplex operation) Maximum 2-wire attenuation: No frequency gap 120 Hz frequency gap with own channel &