480V Bus Duct Sizing for Arar Dated 01.03.2005

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TCE FORM 032 R1

SAUDI ELECTRICITY COMPANY

EASTERN OPERATING AREA

Dammam, Saudi Arabia

GENERATION EXPANSION OF ARAR POWER PLANT

(CONTRACT NO :30421007/00)

DESIGN BASIS

FOR

480V BUS DUCT

SIZING

DOCUMENT NO. : 30421007-3CL-00009-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

01.03-2005 MP SR

P0A

24-08-2004 DG SR

REV NO . DATE PREPARED BY CHECKED BY CLEARED BY APPROVED BY

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CONTENTS

CLAUSE No. DESCRIPTION PAGE No.

1.0 INTRODUCTION 2

2.0 OBJECT 3

3.0 REFERENCES 4

4.0 ASSUMPTIONS / CONSIDERATIONS 5

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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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2.0 OBJECT:

2.1 The object of this report is to determine the ratings of 480V Bus Duct from secondary of 4.16kV/480V Station Auxiliary Transformer to 480V Station Switchgear to be installed at Arar Central Power Station, Saudi Arabia.

2.2 The following parameters are established through this report:

 Continuous Current rating.

 Short circuit withstand and peak withstand current ratings of the Bus Duct.

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3.0 REFERENCES:

3.1 Cl.No.3.03 .8 (a), Page 39 of 336 of PTS-1022 which states that “Two (2) nos. 480V, 3 ph, 4 wire, 3500A, Non Segregated Phase Bus Duct runs connecting LV Auxiliary Transformers #201 & T-202 to the new 480V Station Switchgear”.

3.2 Cl.No.2.0, page 1 of 4 of Data Schedule for “Metal Enclosed Bus Duct 480V” vide which the Short time current withstand capability is defined as 50kA for 1 sec.

3.3 Cl.No.2.0, page 1 of 4 of Data Schedule for “Metal Enclosed Bus Duct 480V” vide which the Continuous current rating at site conditions is specified as 3500A.

3.4 Cl.No.3.0, Page 2 of 4 of Data Schedule for “Metal Enclosed Bus Duct: 480V” of SEC-EOA’s specification vide which the material of bus duct enclosure is specified as Steel.

3.5 Cl.No.3.0, Page 2 of 4 of Data Schedule for “Metal Enclosed Bus Duct: 480V” 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 10th_{Dec 2003, A.53 vide}

which SEC-EOA has informed that Aluminium enclosure also is acceptable for Bus Duct.

3.7 Document No.30421007-3CL-00001-P0E: Unit Auxiliary & Station Auxiliary Transformer sizing report.

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4.0 ASSUMPTIONS/CONSIDERATIONS:

The following assumptions are made for purpose of 480V Bus Duct sizing calculations.

4.1 The 4.16kV/480V Station Auxiliary Transformer rating is considered as 3000kVA as per Document No.30421007-3CL-00001-P0E: Unit Auxiliary & station auxiliary Transformer Sizing report.

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5.0 SIZING CALCULATION :

5.1 Continuous Current rating of 480V Bus Duct: a) 4.16kV/480V Station Auxiliary Transformer

rating = 3000kVA. b) Rated secondary current of 4.16kV/480V

Station Auxiliary Transformer = 3609 Amps. c) Hence, the continuous current rating of

Bus Duct selected at 50 Deg C

& site conditions = 4000 Amps. 5.2 Other parameters of the 480V Non Segregated Phase Bus Duct are

tabulated below:

Sl.No. Parameter Unit 480V Bus

Duct

Reference

1 Type of Bus Duct

Non Segregated,

3 phase, 4 wire Bus Duct

As per Cl No.3.1 above

2 Nominal Voltage rating kV 0.480

As per Cl.No.2.0 of SEC-EOA’s data schedule for 480V Bus Duct 3 Continuous Current

rating at 50 Deg C Amps 4000

As per Cl No.5.1 above 4 Conductor material Copper As per Cl No.3.5_above 5 Enclosure material Aluminium As per Cl.No.3.6

above 6 Short circuit withstand

(Symmetrical) current for 1 sec kA (r.m.s) 65 (45.7kA as per Cl.No.4.12 of System study report for Arar) As per Cl.No3.8 above and as per System Study report for

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Sl.No. Parameter Unit 480V Bus_Duct Reference

7 Peak withstand current ₍_peakkA ₎

137 (113.6kA as per Cl.No.4.12 of System study report for Arar) As per System Study report for