13.8kV Bus Duct Sizing for Arar Dated 23.03.2005

TCE CONSULTING ENGINEERS LIMITED 30421007-3CL-00008-

13.8kV BUS DUCT SIZING REPORT

SHEET OF i i OF 4

SAUDI ELECTRICITY COMPANY EASTERN OPERATING AREA Dammam, Saudi Arabia GENERATION EXPANSION OF ARAR POWER PLANT (CONTRACT NO :30421007/00) DESIGN BASIS FOR 13.8kV BUS DUCT SIZING DOCUMENT NO. : 30421007-3CL-00008-P0B MARCH 2005

ENGINEERING CONSULTANT TCE CONSULTING ENGINEERS LIMITED 73/1, ST. MARK’S ROAD BANGALORE 560 001 INDIA

CONTRACTOR: AL-TOUKHI COMPANY FOR INDUSTRY & TRADING P.O. BOX 497, RIYADH 11411, KINGDOM OF SAUDI ARABIA

TEL. 00966-1-4633660 : FAX. 00966–1-4631150

P0B 23-03-2005

MP

SR

P0A 24-08-2004

DG

SR

REV NO . DATE

PREPARED BY

CHECKED BY

FILENAME : 277758549.doc

CLEARED BY

APPROVED BY TCE FORM 032 R1

TCE CONSULTING ENGINEERS LIMITED 30421007-3CL-00008-

13.8kV BUS DUCT SIZING REPORT

WRITEUP SHEET: 1 OF 8 OF 4

CONTENTS

CLAUSE No.

DESCRIPTION

PAGE No.

1.0

INTRODUCTION

2

2.0

OBJECT

3

3.0

REFERENCES

4

4.0

ASSUMPTIONS / CONSIDERATIONS

6

5.0

SIZING CALCULATION

7

6.0

ANNEXURES ANNEXURE-I - GE DRAWING NO-385A3302, SHEET 4. ANNEXURE-II - GE ELECTRICAL DATA, GENERATOR-DWG NO-385A3308, SHEET 13. ANNEXURE-III - GE ELECTRICAL DATA, GENERATOR-DWG NO-385A3308, SHEET 1 to 15.

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1.0

INTRODUCTION:

1.1

Al-Toukhi company for Industry & Trading has been awarded turnkey contract for Open Cycle Gas Turbine based CPS extension project at Arar of Saudi Electric Company-Eastern Operation Area (SEC-EOA), Saudi Arabia.

1.2

The project consists of design, engineering, procurement, installation, testing and commissioning of two (2) Nos. 60.16MW @ 50C, PG7121 (EA) model Gas Turbine Generator unit of GE make along with associated Generator Transformer and other balance of plant electro-mechanical equipment.

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13.8kV BUS DUCT SIZING REPORT

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2.0

OBJECT:

2.1

The object of this report is to determine the ratings of 13.8kV Bus Duct between Generator Terminals & Generator Circuit breaker panel and from Generator Circuit breaker panel to 13.8kV side of Generator Transformer to be installed at Arar Central Power Station, Saudi Arabia.

2.2

The following parameters are established through this report for 13.8kV Bus Duct: 

Continuous Current rating.



Symmetrical and Asymmetrical current ratings of the Bus Duct.



BIL and Power Frequency withstand values.



Type of Conductor and Enclosure.

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13.8kV BUS DUCT SIZING REPORT

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3.0

REFERENCES:

3.1

Cl.No.3.03 (16), Page 40 of 336 of PTS-1022 which states that “Lot – 13.8kV, 2500A, 3 phase Segregated Phase Bus Duct with required Tap Off connections between Generator and Generator Circuit Breaker Panel and from Generator Circuit Breaker Panel to Generator Transformer”.

3.2

Cl.No.4.03.B, Page 90 of 336 of PTS-1022 which states that “The short circuit rating of 13.8kV Generator Switchgear, Generator Bus Duct and 13.8kV Cables for Unit Auxiliary Transformer shall be 40kA for 3 seconds”

3.3

Cl.No.6.03.G, page 188 of 336 of PTS-1022 which states that “The HV and LV terminals shall be suitable for XLPE cable connection and brought out to an air insulated cable end box. At HV side, the cable end box shall be with Phase Segregated terminal arrangement”

3.4

Data Schedule for “Metal Enclosed Bus Duct: 4.16kV, 13.8kV or 34.5kV”, Cl.No.4.3, Page 12 of 15 of SEC-EOA’s specification vide which the material of bus duct enclosure is specified as Steel.

3.5

Data Schedule for “Metal Enclosed Bus Duct: 4.16kV, 13.8kV or 34.5kV”, Cl.No.4.4, Page 13 of 15 of SEC-EOA’s specification vide which the material of bus duct conductor is specified as Copper.

3.6

SEC-EOA’s Clarification Set No.04 dated 10 th Dec 2003, A.53 vide which SEC-EOA has informed that Aluminium enclosure also is acceptable for Bus Duct.

3.7

SEC-EOA’s Clarification Set No.05 dated 28 th Dec 2003, A.119 vide which SEC-EOA has informed that the gas turbine output enhancement by intake air cooling will be limited to match the maximum generator rating at 50 Deg C.

3.8

Key One Line Diagram – KA-667481 – Rev-P0E

3.9

GE-Electrical Data, Generator-DWG No: 385A3308. Sheet-1 to15 & DWG No-385A3302, Sheet-4.

3.10

Item No.20, Page 6 of 16 of “ List of deviations from SEC-EOA Scope of work and Technical specifications acceptable to SECEOA” vide which deviation was taken that Non Segregated phase ISSUE P0B

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13.8kV BUS DUCT SIZING REPORT

WRITEUP SHEET: 5 OF 8 OF 4

bus duct from GT to Circuit breaker would be provided and Segregated busduct would be provided from Circuit breaker to Transformers.

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4.0

13.8kV BUS DUCT SIZING REPORT

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ASSUMPTIONS/CONSIDERATIONS: The following assumptions are made for purpose of 13.8kV Bus Duct sizing calculations.

4.1

13.8kV side of Unit Auxiliary Transformer is specified to be connected with 13.8kV Cables as indicated under Cl.No.3.2 & Cl.No.3.3 above. In line with “Key One Line Diagram” Drawing No:KA-667481-Rev-P0E, the tap off point from Generator Circuit Breaker, towards unit auxiliary transformer is provided through cables and hence no bus duct tap off link is provided in the 13.8kV bus duct between the Generator Transformer and Generator circuit Breaker.

4.2

Voltage Transformers, Surge Arrestors and Surge Capacitors are proposed to be located as part of 13.8kV Generator Switchgear / GLAC. Hence, no separate tap offs are considered from 13.8kV Bus Duct towards Voltage Transformers, Surge Arrestors and Surge Capacitors.

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13.8kV BUS DUCT SIZING REPORT

5.0

SIZING CALCULATION :

5.1

Continuous Current rating of Main Bus Duct:

WRITEUP

a) GT Unit Output at 50 Deg C under site conditions

=

60.160MW.

1. Generator continuous rated output at 50 Deg C under site conditions

=

65.2 MW.

(The Ambient Temperature 50 Deg C corresponds to a cooling water temperature of 56 Deg C as per GE Drawing No: 385A3302, Sheet no-4. As per the curve given by GE vide drawing no: 385A3308, Sheet-13, at 56 Deg C liquid Temperature, the generator out put is 65.2MW) (TIT may please obtain the confirmation from GE that the Generator output is 65.2MW at 50 Deg C Ambient temperature before submission of this report to SEC since we have assumed that Cooling water temperature is same as Generator liquid temperature) c) Generator rated current at 50 Deg C under site conditions at 13.8kV 0.8 power factor

=

3409.81 Amps.

The Continuous current rating of 13.8kV Bus Duct should not be less than the Generator rated current at 50 Deg C since SEC-EOA has clarified that the gas turbine output enhancement by intake air cooling will be limited to match the maximum generator rating at 50 Deg C. Further, as per Cl.No.4.2.1 of 24SMSS-1 Rev.2, the next standard continuous current rating of Bus Duct is 4000A. d) Hence, the Continuous current rating of Bus Duct at 50 Deg C =

4000 Amps.

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5.2

2

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13.8kV BUS DUCT SIZING REPORT

Other parameters of the 13.8kV Bus Duct are tabulated below:

Sl.No. Parameter 1

WRITEUP

Unit

Type of Bus Duct from Generator Terminals to Generator Circuit breaker panel Type of Bus Duct from Generator Circuit breaker panel to 13.8kV side of Generator Transformer

3

Nominal Voltage rating

4

Continuous Current rating at 50 Deg C

13.8kV Main Bus Duct Non Segregated Phase Bus Duct Segregated Phase Bus Duct

Reference As per Cl.No.3.10 above As per Cl No.3.1 above

KV

13.8

Amps

4000

As per Cl.No.4.2 of 24SMSS-1 Rev .2 As per Cl No.5.1 above

5

Conductor material

Copper

As per Cl No.3.5 above

6

Enclosure material

Aluminium

As per Cl.No.3.6 above.

7

Basic Insulation level

8

Power Frequency withstand voltage

9

Short circuit withstand (Symmetrical) current for 3 sec

10 10

Peak withstand current

11

Short circuit withstand (Asymmetrical) current

kV

kV

kA (r.m.s) kA

95

36

40 108.10

(peak) kA

60.1

As per Cl.No.4.2 of 24SMSS-1 Rev .2 As per Cl.No.4.2 of 24SMSS-1 Rev .2 (Min 38.70kA as per Cl No.4.9 of System Study report for Arar) As per Cl No.4.9 of System Study report for Arar As per Cl No.4.9 of System Study report for Arar ISSUE P0B