electrical operating philosophy ji 191 el 08 0000 10006 rev 0

TITLE :

Electrical System Operating Philosophy

0 Issued for Design 04/03/2010 SVU VS KR MM

B Issued For Approval 06/12/2009 SVU VS KR MM ORIG. DOC SIZE:

A4 This is a Word document and must not be altered

manually Rev.

REV DESCRIPTION DATE PRPD CHKD APPD APPD DOC NO. JI-191-EL-08-0000-10006 of 64 0

Jihar stage 3 Project

HPC Contract No.: HPC/08-06

Petrofac Job No.: JI-191


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TABLE OF CONTENTS

SL.NO. DESCRIPTION PAGE NO.

1.0 INTRODUCTION 3

2.0 OBJECTIVES 3

3.0 ABBREVIATIONS USED IN THE DOCUMENT 4

4.0 REFERENCE DOCUMENTS 4

5.0 UTILIZATION VOLTAGE LEVELS (NOMINAL) 6

6.0 ELECTRICAL POWER DISTRIBUTION SYSTEM 7

6.1 GTP POWER DISTRIBUTION 7 6.2 LQ POWER DISTRIBUTION 11 6.3 SGS JIHAR POWER DISTRIBUTION 11 6.4 SGS AL-MAHAR POWER DISTRIBUTION 12 6.5 TIE-IN AT T4 AREA 12

7.0 SUBSTATION DIGITAL CONTROL SYSTEM 13

8.0 MAJOR ELECTRICAL EQUIPMENT/ITEMS AT VARIOUS LOCATIONS 14

8.1 GTP 14 8.2 LQ 15 8.3 SGS JIHAR 15 8.4 SGS AL MAHAR 15 8.5 TIE-IN AT T4 15

9.0 INDIVIDUAL EQUIPMENT DESIGN, OPERATION AND CONTROL PHILOSOPHY 16

9.1 POWER GENERATORS 16 9.2 EMERGENCY DIESEL GENERATOR SET 20 9.3 6.6KV MV SWITCHBOARD (6.6KV-SWG-01 AT GTP, JIHAR) 26 9.4 DISTRIBUTION TRANSFORMERS 29 9.5 LV SWITCHBOARDS 31 9.6 DISTRIBUTION BOARDS FOR LIGHTING, HVAC, HEAT TRACING & CATHODIC PROTECTION 40 9.7 230V AC UPS SYSTEM 42 9.8 110V DC UPS SYSTEM 50

10.0 PLANT OPERATION PROCEDURE - GTP 51

10.1 CONDITION A - PLANT ELECTRICAL SYSTEM START-UP PROCEDURE ON ISLAND MODE OF OPERATION 51 10.2 CONDITION B -PLANT ELECTRICAL SYSTEM START-UP PROCEDURE WITH THE PRESENCE OF GRID

SUPPLY 55 10.3 CONDITION C- PLANT NORMAL OPERATING CONDITION - GTP 58 10.4 CONDITION D - PLANT ABNORMAL OPERATING CONDITION -GTP 59

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1.0 INTRODUCTION

This document covers the Operating and Control Philosophy for the Electrical Power

Generation and Distribution network of the GTP Jihar, LQ, SGS Jihar and SGS Al

Mahar. This document provides a brief description of the system and their envisaged

operation philosophy.

2.0 OBJECTIVES

Hayan Petroleum Company (HPC) is a joint-stock Company owned equally between

the Syrian Petroleum Company and INA INDUSTRIJA NAFTE d.d. Naftaplin.

HPC is installing a Gas Treatment plant at Jihar with Gathering and Transport

System (Jihar Stage-3 Project) in the area located 15 km north-west of Palmyra City

in the Syrian Arab Republic.

The Jihar Stage-3 Project Scope Consists of the following facilities and installations:

Central Gas Treatment Plant ( GTP) Jihar

Satellite Gas ( Gathering) Station (SGS) Jihar

Gathering system Al Mahar (well sites and flow lines of Al Mahar wells)

Gas Collecting Point Al Mahar (GCP Al Mahar);

Gathering system Jihar (well sites and flow lines of Jihar wells) with salt

water disposal in the dry well Jihar-3;

Transport pipelines system to GTP Jihar from GCP Al Mahar (12” gas and

4” condensate) and from SGS Jihar (10” gas and 6‟ condensate);

Water feed from existing water well near the production well Jihar 2;

The objective of the Electrical system operating and control philosophy is to act as

the top level document for the operation and control of the Electrical

Equipments/systems.

This operation and control philosophy covers the following aspects:

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Description of the power system and its design parameters

Operating Philosophy, Protection, Controls, interlocks and monitoring provided

for each of the equipment

3.0 ABBREVIATIONS USED IN THE DOCUMENT

AMF - Auto-Mains Failure

AVR - Automatic Voltage Regulator

CSP – Common Synchronising Panel

DB - Distribution Board

EDG - Emergency Diesel Generator

ESD - Emergency Shutdown System

GCP - Generator Control Panel

Grid - Syrian National Grid ( Future Provision)

GTG - Gas Turbine Generator

ICSS - Integrated Control & Safety System

MCC - Motor Control Centre

NGR - Neutral Grounding Resistor

SDCS - Substation Digital Control System

TCP - Turbine Control Panel

UCP - Unit Control Panel

UPS - Uninterrupted Power Supply

VSD - Variable Speed Drive

4.0 REFERENCE DOCUMENTS

Electrical Design Basis - JI-191-EL-08-0000-10001

Key Single Line Diagram - JI-191-EL-13-2970-10002

Electrical Load Schedule - JI-191-EL-01-2970-10002

Single Line Diagram – T4 Area - JI-191-EL-13-2200-10003

Single Line Diagram - Switchboard 6.6kV-SWG-01 - JI-191-EL-13-2970-10002

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Single Line Diagram –Switchboard PMCC-0.4 kV-SWG-01 -JI-191-EL-13-2970-10004

Single Line Diagram –Switchboard PMCC-0.4 kV-SWG-02 -JI-191-EL-13-2970-10005

Single Line Diagram –Switchboard 0.4kV-GAS GEN-MCC-01 -JI-191-EL-13-2970-10015



Single Line Diagram –Switchboard Admin-PCC-01 - JI-191-EL-13-2970-10009

Single Line Diagram – Switchboard LQ-PMCC-01 - JI-191-EL-13-0000-10010

Single Line Diagram – Switchboard SGS-PMCC-01 - JI-191-EL-13-3300-10001

Single Line Diagram – Switchboard AlMahr-0.4kV-SWG - 01 -JI-191-EL-13-4300-10001

Protection & Logic Diagram – 6.6kV Switchboards - JI-191-EL-15-0000-10001

to 10005

Block Logic Diagram – Motor Feeder - JI-191-EL-15-0000-10010

to 10013

System Block Diagram for Substation Digital - JI-191-EL-15-0000-10019

Control System

Short Circuit System Study/ Load Flow and - JI-191-EL-08-0000-10002/

Motor Starting System Study/ Transient 10003/10005

Stability Study for Jihar-GTP/SGS/LQ/Al Mahar

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5.0 UTILIZATION VOLTAGE LEVELS (NOMINAL)

For motors rated at 0.18 kW up to & less than 150 kW.

: 400V AC, 3 PH, 3 wire + PE, 50 Hz system neutral solidly earthed.

Three Phase power main feeders including Battery chargers, UPS, HVAC, bulk AC loads (like Process heaters, Welding Socket Outlet), Power & Lighting Distribution Panels etc.

System, Welding Outlet & Miscellaneous loads

: 400V AC, 3 PH, 3 wire + PE, 50 Hz system neutral solidly earthed.

For motors rated below 0.18 kW, Control supply for Low voltage motor starter and switchgear auxiliaries , Anti-condensation space heaters, Convenience outlets, Plant illumination system (Normal & Emergency Lighting), Electrical Heat Tracing etc.

: 230V AC, 1 PH, 2 wire + PE (TN-S system), 50 Hz, system neutral solidly earthed.

Control Supply for Medium Voltage switchgear circuit breakers & contactors, control supply for Low voltage Main Switchgear incomer & bus-tie circuit breaker, DC motors for emergency Lube oil pumps, etc.

: 110V DC, 2 Wire (Un-earthed) (see note 2)

Instrument Supply, Compressor UCPs, Fire & Gas detection system, Cathodic protection monitoring system etc.

: 24 V DC, 2 wire (see note 1)

DCS, ESD, PLC, SDCS & Telecom etc,

: 230V AC, UPS (see note 1)

Voltage Variation : +/- 5 %

Frequency Variation : +/- 2 %

Notes: 1. Only 230V AC UPS dual redundant supply will be made available for all

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instrumentation equipments. Further 48V or 24V DC supply, will be derived

internally by instrumentation vendor.

2. For the LV Switchboards at LQ, SGS Jihar and SGS Almahar the main

switchgear incomer breakers shall be provided with inbuilt protective

releases. The 110V DC for breaker trip coil requirement is internally derived

from AC/DC converter provided within the switchboards.

3. Motor rated > 150 kW and fed from VSD shall be rated for 400V.

6.0 ELECTRICAL POWER DISTRIBUTION SYSTEM

The Electrical Power Distribution for the GTP Jihar, LQ and SGS Jihar is as detailed in

the Key Single Line Diagram No. JI-191-EL-13-2970-10002 and for SGS Al Mahar is as

detailed in Drg No. JI-191-EL-13-4300-10001 and for T4 area is as detailed in Single

Line Diagram-T4 Area Drg No.– JI-191-EL-13-2200-10003.

6.1 GTP Power Distribution

6.1.1 The GTP, Jihar has been designed to be self sufficient to cater to own electrical

power requirements. The Power Generation System of GTP, Jihar will provide main

power supply to the Plant, equipped with three 6.6 kV Gas Turbines Generating Units

(GTGs). The GTG‟s are designed to be 3 x 50% capacity with two operating and one

standby configuration. The main power supply will serve all electrical functions

(normal, emergency and essential services) during normal operation.

6.1.2 In addition the 6.6kV Switchboard at GTP, Jihar will be equipped to receive incoming

Syrian Grid supply (66kV) in future via a 66kV/6.6kV Step down grid transformer,

which would act as a standby supply from the Public Network, made available by the

“Syrian Establishment for Distribution & Utilization of Electrical Energy”, owner of

the National Grid.

6.1.3 Power generated at 6.6kV will be fed to the 6.6kV-SWG-01 for further distribution to

the following areas:

Jihar Gas Treatment Plant ( GTP)

Living Quarters Area (L.Q.) approximately 1 km. by underground

Cable.

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Remote Jihar Satellite Gas Station (SGS) approximately 3.5 km. by

overhead line.

Jihar Phase-2 – The power transfer from Phase-3 to Phase-2 is

restricted and is allowed only under dead bus condition at Jihar

Phase-2 switchboard. No Parallel operation of Jihar Phase-2 and

Phase-3 source is allowed. To ensure the same, necessary key

interlock to be provided by HPC at the receiving 20 kV Switchboard at

Jihar Phase-2.

6.1.4 The bus-bar system of Main 6.6kV Switchgear will have three bus sections (Bus “A”,

Bus “B” & Bus “C”) interconnected with two bus-coupler breakers. The bus-coupler

breakers shall act as isolators without any protection element. All the MV motors of

the GTP i.e. motors > 150 kW (except for Produced Water Pump Motor rated at

315kW and will be fed from VSD rated at 400V) is fed from the 6.6kV Switchboard.

6.1.5 The 6.6kV supply voltage from 6.6kV-SWG-01 will be stepped down to 400V via

ONAN type step down transformers to feed the LV loads of the following

switchboards as indicated in the Key SLD :

- PMCC-0.4kV SWG-01 via Step down transformers 2970-GTP-TR-01 & 2970-

GTP-TR-02

- PMCC-0.4kV SWG-02 via Step down transformers 2970-GTP-TR-03 & 2970-

GTP-TR-04

- ADMIN-PCC-01 via Step down transformer 2970-ADMIN- TR-01

- SGS- PMCC-01 via Step down transformer 3300-SGS TR-01

- LQ -PMCC-01 via Step down transformer 3500- LQ TR-01

6.1.6 The PMCC-0.4kV-SWG-01 & 02 are provided with two bus sections – Bus A and Bus B

with an interconnecting bus coupler breaker. The PMCC-0.4kV-SWG-01 will also

receive incomer feed from the GTP Emergency DG set. Accordingly all the

emergency and essential loads of Jihar GTP will be connected to the PMCC-0.4kV-

SWG-01.

All the GTP normal process loads will be connected to PMCC-0.4kV-SWG-02, except

for Produced Water pump motor which will be fed from PMCC-0.4kV-SWG-01.

However this motor will be shutdown when PMCC-0.4kV-SWG-01 is powered from

EDG. Necessary interlock will be created in the PMCC-0.4kV-SWG-01 to prevent the

non essential loads such as produced water pump, nitrogen generation package etc,

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to start when the DG set is feeding the essential loads.

6.1.7 In normal operation the loads of the PMCC-0.4kV-SWG-01 and 02 will be fed from the

main power system (i.e. GTG/grid supply) via step down transformers. The two

incoming circuit breaker and the bus tie circuit breaker shall be fitted with an

automatic change-over system and an integral auto-transfer facility to allow short

time parallel operation. In normal operating condition the two installed transformers

of PMCC-0.4kV-SWG-01 and 02 shall feed power with the bus circuit breaker kept

open. In case of fault in any one of the two transformers of a particular switchboard,

the associated circuit breaker trips and an automatic changeover system will close

the bus tie breaker thus providing power to the entire switchboard.

For PMCC-0.4kV-SWG-01, in the event of total loss of up-stream supply (i.e. Failure

of GTG and grid simultaneously if grid is in circuit), the 1250 kVA Emergency DG set-

GTP-DG-01 will automatically start and provide power to the connected essential

and emergency loads of the plant. This EDG is connected to the PMCC-0.4kV-SWG-01

via dual breakers with manual changeover facility to connect to Bus-A or Bus-B

based on emergency Circuit Breaker selected by the operator. This facility has been

provided to create redundancy in the DG breaker to ensure that even in the event of

fault in one of the bus section/ breaker, the Emergency power is made available via

the other healthy bus section/ breaker.

6.1.8 The auxiliaries of the GTG‟s will be fed from dedicated 0.4kV GTG MCC‟s ( 0.4kV-

GAS-GEN-MCC-01/02/03) fed via dual feeders from the PMCC-0.4kV-SWG-01 as

detailed in the Key SLD. All GTG MCC‟s will be equipped with double incoming „on-

load‟ type switch, mechanically (key) interlocked with manual change over facility.

6.1.9 The Administration Area PCC (ADMIN-PCC-01) will be placed in the MCC room of

administration building substation. The auxiliary loads in and around the

Administration building viz. HVAC, Workshop loads, Fire station loads etc. will be

fed from this PCC. The normal power from ADMIN-PCC-01 to the 400/230V auxiliary

services such as lighting and small power distribution, welding sockets , receptacles

etc, will be fed via ADMIN-LTG-TLL-01 isolation transformer and distributed through

0.4/0.23 kV – Lighting and Small Power DB (MLSPDB-2970-01). The dry type isolation

transformers have been provided to reduce the short circuit current level, thus

enabling the use of lighting circuit breakers of MCB type. The above isolation

transformers (ADMIN-LTG-TLL-01) will be equipped with double incoming „on-load‟

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type switch or MCCB; mechanically (key) interlocked with manual change over

facility thus providing redundancy in supply.

6.1.10 The normal power from PMCC-0.4kV-SWG-02 to the 400/230V auxiliary services such

as lighting and small power distribution, welding sockets , receptacles etc, will be

fed via NLDB/SP-TLL-01 isolation transformer and distributed through 0.4/0.23 kV -

Aux. Service Panel / Light Panel (NLDB/ ASP-01). The normal cum emergency power

from PMCC-0.4kV-SWG-01 to the normal cum emergency 400/230V auxiliary

services such as lighting and small power distribution, receptacles, space heater

supply etc., will be fed via ELDB-TLL-01 isolation transformer and distributed

through 0.4/0.23 kV - Aux. Service Panel / Light Panel (MELDB-01). The dry type

isolation transformers have been provided to reduce the short circuit current level,

thus enabling the use of lighting circuit breakers of MCB type. The above isolation

transformers (NLDB/SP-TLL-01 & ELDB-TLL-01) will be equipped with double

incoming „on-load‟ type switch or MCCB, mechanically (key) interlocked with

manual change over facility thus providing redundancy in supply.

All main indoor lighting and small power DB‟s are provided with incomer MCCB

feeder and outgoing MCB feeders. All main outdoor lighting and small power DB‟s are

provided with incomer isolator feeder and outgoing MCB feeders.

6.1.11 Essential power for Jihar GTP will be met by 230V AC UPS system and 110 V DC

systems. The voltage levels and the autonomy time for the various essential system

loads are as detailed below:-

6.1.12 The 110V and 24V DC UPS requirement for the GTG‟s will be derived from dedicated

DC UPS systems which are part of the GTG package.

230V AC UPS for Instrumentation

(230V-UPS-02)

: 230V AC output, dual redundant,

Battery autonomy time of 8hrs with

additional power supply by a dedicated

Emergency DG set.

UPS Lighting (230V-UPS-04) : 230V AC output, single charger,

Battery autonomy time of 8 hrs.

GTP Switchgear breaker controls

(110V-DCP-03)

: 110V DC output, single charger,

Battery back-up time of 12 hrs

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6.2 LQ Power Distribution

The power supply to the LQ-PMCC-01 will be fed from 6.6kV-SWG-01 through a single

6.6/ 0.42 kV Step down transformer (3500-LQ-TR-01).

6.2.1 The LQ-PMCC-01 shall meet the HVAC, Lighting and other miscellaneous load

requirements of the LQ area. The normal power from LQ-PMCC-01 to the 400/230V

auxiliary services such as lighting and small power distribution , welding sockets ,

receptacles etc, will be fed via LQ-LDB-TLL-01 isolation transformer and distributed

through 0.4/0.23 kV – MLSPDB-3500-01. The dry type isolation transformers have

been provided to reduce the short circuit current level, thus enabling the use of

lighting circuit breakers of MCB type. The above isolation transformers (LQ-LDB-TLL-

01) will be equipped with double incoming „on-load‟ type switch , mechanically (key)

interlocked with manual change over facility thus providing redundancy in supply.

The emergency power to MLSPDB-3500-01 will be fed by dedicated 200kVA LQ

Emergency DG Set (LQ-DG-01). Auto Mains Failure logic has been provided for LQ-

DG-01 to start automatically on loss of normal power supply to MLSPDB-3500-01.

No UPS supply is envisaged for LQ area as the Emergency DG set at LQ is provided

with its own battery bank for starting purpose and for GCP control.

6.3 SGS JIHAR Power Distribution

The power supply to the SGS-PMCC-01 will be fed from 6.6kV SWG-01 via 6.6kV

Overhead line through a single 6.6/ 0.42 kV Step down transformer (3300-SGS-TR-

01).

The SGS-PMCC-01 shall meet the process, HVAC, Lighting and other miscellaneous

load requirements of the SGS Jihar. The normal power from SGS-PMCC-01 to the

400/230V auxiliary services such as lighting and small power distribution, welding

sockets, receptacles etc, will be fed directly via lighting and small power

distribution boards.

In addition the instrumentation loads of the SGS Jihar will be fed by 230V dual

redundant AC UPS (230V-UPS-06) with Battery back-up of 24 hrs for DCS, ESD and

F&G systems where as back up time for other instrumentation loads will be 8 hours.

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No Emergency DG supply is envisaged for SGS Jihar.

6.4 SGS Al-Mahar Power Distribution

The power supply at remote Al-Mahar SGS facility will be derived from 2 x 100%

Diesel Generators sets- MHER-DG-01A and 01B working in One running and one

stand by configuration . In the event of failure of the working EDG, the standby EDG

will be started automatically. In addition synchronising facility has been provided for

live manual change over from the operating DG to the standby DG in case the

operating DG set need to be taken out for planned maintenance without break in

supply. This is a standalone system and is not connected to Jihar GTP.

The DG power will be fed to Almahar-0.4kV -SWG-01 which will meet the process,

HVAC, Lighting and other miscellaneous load requirements of the SGS Al-mahar area.

The normal power from Almahar-0.4kV -SWG-01 to the 400/230V auxiliary services

such as lighting and small power distribution, welding sockets, receptacles etc, will

be fed directly via lighting and small power distribution boards.

In addition, the instrumentation and telecom loads of Al-Mahar will be fed by dual

redundant 230V AC UPS system (230V-UPS-05) with a battery back-up of 8 hrs.

6.5 Tie-in at T4 Area

A single point power supply at T4 existing substation will be provided by the

Company. A new Distribution board T4-NDB-01 will be placed in this existing

substation building to derive this single point power supply.

Power supply from T4-NDB-01 to the T4 Porta cabin Distribution board (T4-NDB-02),

which is located approx. 350mtr, will be fed by underground cables.

The T4-NDB-02 will meet the non UPS instrumentation, HVAC, Lighting and other

miscellaneous load requirements of T4 area.

In addition, the instrumentation and telecom load of T4 tie-in will be fed by dual

redundant 230V AC UPS system (230V-UPS -07) with a battery back-up of 4 hrs.

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7.0 SUBSTATION DIGITAL CONTROL SYSTEM

Separate PC-based Substation Digital Control System (SDCS) is being provided at the

GTP MCC building for system monitoring via Integrated Protection and Control

Devices (IPCDs). The SDCS system configuration is as detailed in system Block

Diagram for Electrical Substation Digital Control System (SDCS)- JI-191-EL-15-0000-

10019.

The SDCS provided at the MCC building will communicate with selected individual

electrical equipments associated with a particular substation via serial link/

hardwired signal. In addition the SDCS is linked to the upstream plant Digital Control

System (DCS) via serial communication link. The DCS is being provided in the Control

room of the MCC building for plant process control and monitoring. The SDCS will

act as gateway between Digital Control System (DCS) and Electrical Power

Equipment. In addition the SDCS at GTP will monitor the status of the power system

at SGS Jihar and SGS Al Mahar via the DCS at the respective locations as detailed in

the Block Diagram – JI-191-EL-15-0000-10019.

The monitoring function, to be carried out by the SDCS with respect to the

individual equipment is as detailed in the following sections. The SDCS will also

provide Sequence of Event (SOE) reports including running time, number of starts

and number and type of trips. It will also carry out recording of all events, date and

time stamped for all circuits connected, with printout facilities including

running/stopped/ alarm/trip.

The electrical equipments of GTP connected with the SDCS are as follows:

Three nos. Generator Control Panels, each with Intelligent Generator

protection relay.

66 kV Control & Relay Panel with Intelligent Feeder Protection Relay – only

provision is made and no programming done presently, as no data is available

with PEC for this future grid connection.

6.6 kV Switchboard ( 6.6kV-SWG-01) with intelligent motor protection and

transformer protection relay

400V Normal Cum Emergency Switchboard (PMCC-0.4kV-SWG-01)

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400V Normal Switchboard (PMCC-0.4kV-SWG-02)

400V GTG MCCs ( 0.4kV-GAS GEN- MCC-01/ 02 / 03)

Emergency DG Set Control Panel (EDG GCP)

VSD Panel of Produced Water Pump Motors

230V-UPS-02 & 04, 110V-DCP-03.

8.0 MAJOR ELECTRICAL EQUIPMENT/ITEMS AT VARIOUS LOCATIONS

8.1 GTP

6.6 kV Gas Turbine Generators

6.6 kV MV Switchboard

6.6 / 0.420 kV Power Transformers

400V Normal LV Switchboard

400V Normal cum Emergency Switchboard

400V MCC‟s ( GTG )

400V PCC ( Admin Area )

0.42 / 0.42 kV Isolation Transformers

400V Emergency DG Sets

Variable Speed Drive

Thyristor Control Panel

Substation Digital Control System

230V AC UPS

110V DC UPS

Distribution Boards

Cathodic Protection system

Heat Tracing system

Lighting Fixtures & Lighting Junction boxes

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8.2 LQ

6.6 / 0.420 kV Power Transformer

400V Normal Switchboard

0.42 / 0.42 kV Isolation Transformer

400V Emergency DG Set

Distribution Boards


8.3 SGS Jihar

6.6 / 0.420 kV Power Transformers

400V Normal LV Switchboards

230V AC UPS

Distribution Boards


Heat Tracing system


8.4 SGS Al Mahar

400V Normal cum Emergency Switchboard

400V Normal cum Emergency DG Sets

230V AC UPS

Distribution Boards


Heat Tracing system


8.5 Tie-in at T4

Distribution Board

Lighting Fixtures & Lighting Junction boxes.

230V AC UPS

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9.0 INDIVIDUAL EQUIPMENT DESIGN, OPERATION AND CONTROL PHILOSOPHY

9.1 Power Generators

9.1.1 Gas Turbine Generators Design:

The main power source for the Jihar process facility is Gas Turbine driven

Generators. The main power generation and distribution voltage is selected as 6.6

kV. The Plant total load requirement is as detailed in Electrical Load Lists (JI-191-EL-

01-2970-10002 & JI 191-EL-06-4300-10002).

During normal operation, the total power requirement of Jihar GTP/SGS/LQ will be

met by 2 nos. 9000 kW, 6.6 kV, 3 phase, 50Hz, Gas Turbine Generators operating in

parallel. In Island mode of plant operation, it is envisaged to operate two GTG‟s in

parallel sharing total plant running load and the third generator will be maintained

as a standby generator. The standby generator will be brought into service in case of

planned shutdown of the running generator for maintenance or in the event of

tripping of any one of the operating generators due to fault.

Equal Sharing the load between two running GTGs at any given point of time is

controlled by the in-built VAR and Watt load sharing module provided in the CSP

(For details refer DEIF - User Manual). Each generator has a dedicated Generator

control and protection panel (GCP) including the excitation system, Automatic

Voltage Regulator, Generator protection relays and other accessories and a Unit

Control Panel (UCP) for Turbine Control and protection. In addition a Common

Synchronising Panel (CSP) is provided for the Synchronising and Control of the three

GTG‟s and also On/Off control of the Grid Incomer breakers.

Based on the damage curve furnished by the Generator manufacturer, an impedance

earthing philosophy has been adopted for the MV system and accordingly the neutral

of each of the generator can be connected to earth via Neutral Grounding Resistor

(NGR), which will restrict the earth fault current to 200 A.

Each NGR is equipped with Vacuum contactor suitable for remote operation from

CSP. The logic provided in the common synchronising panel shall ensure that out of

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the running Generators only one of the Generator Neutral shall be earthed at any

given time and in the event of generators operating in parallel with the grid, the

GTG NGR‟s are not connected in circuit. On/off status and alarms for NGR‟s are

provided on Common Synchronising panel Mimic panel.

The Gas Turbine Generators and NGRs will all be located outside the MCC building at

a distance of around 120 meters.

The Generator Control Panel, Unit Control Panel and Common Synchronising panel is

located in the SDCS room which is within the MCC building.

9.1.2 GTG Operation & Control Philosophy:

Generator Control – From GCP and CSP.

Turbine Control - From UCP.

Status Monitoring – At GCP /CSP / SDCS / DCS.

Generator Protection – At GCP.

For the Generator control and protection, each of the 3 GTGs is provided with

Generator Control Panel (GCP) and a Common Synchronising Panel (CSP).

a) The CSP shall house the generator control and metering equipment as below:

DEIF Auto synchroniser, DEIF Active load sharing controller, Reactive load

sharing controller.

The CSP is also provided with both manual and automatic synchronising

facility of the GTG‟s with the grid. However during the parallel operation of

the GTG‟s with the grid the load sharing control will be carried out by the

SDCS. The SDCS monitors the total power requirement of the plant and based

on the total power demand on the system, calculates the amount of the fixed

power to be drawn from the grid (based on the set point input from the

operator) and the variable power to be drawn from the GTG‟s and

accordingly provides the necessary 4-20mA control signals for kVAR control to

the AVR and kW control to the governor for each of the GTG‟s. The SDCS

provides 4-20mA signals to the individual generator GCP / UCP panels thus

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controlling the amount of active and reactive power to be generated by each

of the GTG‟s.

Analogue meters including synchroscope, synchronising voltmeter,

synchronising frequency meter.

Control/ Selector switches including – Generator CB Open/ close switch, Bus

tie CB Open/ Close switch, NGR contactor Open/ Close switch, Synchronising

selector Off / Manual / Semi–auto / remote-auto selector switch, Common

speed lower/ raise control switch, Common voltage lower/ raise control

switch, Dead bus synchroniser enable switch.

b) The GCP shall house :

Siemens – 7UM 62 -Composite Numerical Generator protection relay

covering the following protection function – 87G- unit differential, 51V-

voltage restrained overcurrent, 51-N- sensitive earth fault, 40 – field

failure, 32R- reverse power, 46 - unbalance load alarm/ trip, 59- Over

voltage, 27- undervoltage, 67N- sensitive directional earth fault, 81 U/O –

over-frequency / under-frequency alarm/ trip, 58- Excitation fault. 64R-

Rotor earth fault protection is provided by Rotogaurd housed within the

generator.

ABB Unitrol 1000 AVR module

Analogue meters including Generator & Field Ammeter, Frequency meter,

MW, MVAR meter, voltmeter, power factor meter and MWh meter.

Digital multifunction energy meter

Control/ Selector switches including – excitation manual/ auto control

selector switch, excitation On/ Off control switch, excitation voltage

lower/ N/ raise control switch, Local/ Remote selector switch ,Volts/pf

control switch, governor lower/N/ raise control switch , digital

multifunction meter

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The GCP provides facility for both manual and auto synchronisation of the

generators. The GTG starting and synchronising is carried out by the operator from

the GTG UCP. The synchronising process can be carried out either in manual mode or

in auto mode as decided by the operator. Once the system is ready for synchronising

the incomer MV breaker close command is initiated by the CSP via hard wired signal

and the generator is synchronised to the bus.

The generator status, protection and metering signals are available on the GCP front

panel. In addition these signals are communicated from the GCP to the SDCS via

serial link.

The control supply of the GCP /CSP is 24 V DC and is derived from dedicated VRLA

battery system being supplied as part of the GTG package.

9.1.3 Parallel operation of the GTG‟s with Syrian Grid:

In Grid parallel operation mode, two GTG‟s are envisaged to operate in parallel with

one of the grid incomer feeder sharing the total plant normal running load. Due to

the fault level restriction on the 6.6kV switchboard, parallel operation of two GTG‟s

with only one grid incomer feeder is allowed. Necessary mechanical and hardwired

interlock have been provided in the Common synchronising panel to disallow parallel

operation of two Grid incomers at the same time and parallel operation of the three

GTG‟s with the Grid.

During the future scenario of GTG‟s operating in parallel with the grid, the two

running generators will be set to deliver the total power requirement of the plant

and the grid will be kept floating on to the system to meet a minimum floating

power requirement and the same is to be set by the operator at the SDCS. In case of

tripping of any one of the operating generators, the grid will make up for the short

fall of power only to the extent as set by the operator on the SDCS.

The System Study Reports including the Transient Stability Study, Load Flow Analysis

Report and the Short Circuit Report have detailed the power flow and response of

the system during various operating scenario.

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Note:

While implementing the above Syrian Grid interface to the 6.6 kV System, Company

to take into account the following design criteria for the tie-in connection:

a) The Grid Transformer Rating and impedance to be selected such that the total

short circuit contribution of the grid when operating in parallel with two GTG‟s to

be limited to 50 kA ( i.e. within the rated short circuit capacity of the 6.6kV

switchboard).

b) The earth fault current at the 6.6kV system to be restricted to 200A by providing

suitably rated NGR and earth fault settings taking into account the Stator Damage

curve of the Siemens GTG‟s. In the event of Generator operating in parallel with

the Grid, the GTG NGR need to be disconnected from circuit and the NGR

provided on grid incomer transformer need to be earthed. The sizing of the grid

transformer NGR shall be carried out by HPC taking into account the stator

damage curve of the GTG.

9.1.4 Interlocks

Necessary interlocks have been created within the CSP to ensure the following:

- Prevent closing of the grid incomer feeder when three of the GTG‟s are

operating in parallel.

- Prevent closing of the GTG NGR contactor‟s when the grid NGR is in circuit.

9.2 Emergency Diesel Generator Set

9.2.1 1250 kVA Emergency DG Set Design (GTP-DG-01 at GTP, Jihar)

The emergency load requirement of GTP is met by 1 no. 400V, 50 Hz, 1250 kVA

Emergency Diesel Generator set. The emergency generator is designed to feed power

to the Normal-cum-emergency switchboard to meet the essential service/start-up

load requirement as indicated in the Electrical Load List- JI-191-EL-01-2970-10002.

The DG set is designed to start automatically on loss of main power. The EDG set

package is complete with Local control panel, AVR, gauges, starting battery,

excitation system, other accessories within the EDG enclosure and a remote GCP

panel located within the MCC building SDCS room which contains the protective

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relays and meters. The neutral of the DG set is solidly earth. The DG set is provided

with facility for no load trial from the local control panel at the DG skid.

9.2.2 1250 kVA Emergency DG Set Operation & Control Philosophy:

DG Control – From DG GCP

DG Protection – DG GCP

DG Status Monitoring – DG GCP/ SDCS

The status monitoring of the EDG is carried at the EDG GCP and from remote SDCS

via Serial Link.

During normal operation, the Main GTGs/ Grid are feeding power to the system, the

transformer incomer from the 6.6kV-SWG-01 to the normal cum emergency

switchboard –PMCC-0.4kV-SWG-01 is in „closed‟ condition, the bus coupler breaker

and the incomer breakers from EDG set are in „open‟ condition.

The EDG set will automatically be brought into service on loss of the main power

supply from the GTGs. On loss of power from the Main GTGs, and on sustained

simultaneous under voltage condition on both the transformer incomer lines EDG

GCP PLC will initiate an auto start command to the EDG.

In addition to the above, the EDG set is also provided with synchronising facility to

enable re-instatement of the normal supply on to the PMCC-0.4kV-SWG-01 on

resumption of GTG/Grid power for bump less, make before break, reinstatement of

normal power to the essential services system.

Under plant normal operating condition periodic no load test on the EDG set is to be

carried out by the operator to ensure the healthiness of the EDG set. The normal

cum emergency switchboard is not designed for the short circuit current that could

occur during the load trial of the DG set during parallel operation of the DG set with

the transformer.

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The EDG control panel will house the protective relay of the EDG covering the

following protection functions:

Voltage Controlled time dependent over-current relay (51V), Over-voltage/ Under-

voltage relay (59/27), Inverse Definite Minimum Time Lag Overcurrent Relay (51),

Negative Phase Sequence Relay (46), Frequency Relay (81), Earth fault Relay (51G),

Instantaneous Over current Relay (50).

9.2.3 200 kVA UPS DG Set Design (UPS-DG-01 at GTP, Jihar)

The 200 kVA UPS DG set is designed to feed power to the Plant Instrument UPS

(230V-UPS-02) in the event of failure of the main 1250 kVA DG set to start under

normal power failure condition. The start of the 200kVA UPS DG set is manual and

need to be initiated by the operator on receipt of Main DG set start failure alarm on

the SDCS. On failure of auto starting of the main 1250 kVA DG set under a plant

emergency condition the 200kVA UPS DG set need to be started manually within a

time frame of 15 minutes as this DG set is not designed to cater to simultaneously

the charging current of the UPS battery and the UPS load under a battery discharged

condition.

The UPS DG set is controlled from the UPS DG GCP placed in the MCC building SDCS

room. On receiving the main 1250 kVA DG set starting failure alarm on the SDCS

panel, the operator to initiate a manual start of the UPS DG at the DG GCP. On

receipt of the DG set ready to take load feedback on the DG GCP, the operator to

manually operate the three position incoming supply changeover switch on the UPS

panel and change the position of the switch from mains supply to DG supply thus

bringing in the DG power to feed the UPS system. In case all the three change over

switches are not on the same source of supply a discrepancy alarm will be generated

Local to panel and remotely at the SDCS. On resumption of normal GTG/ Grid supply

or the main 1250 kVA emergency DG supply the operator to manually switch off the

UPS DG set after unloading and bring in the main supply. There is no synchronising

facility available for the UPS DG at the UPS DG GCP panel. However there is no break

in the UPS supply to the load as the UPS battery will be feeding the load during this

transition phase from the Main supply to DG supply and vice versa.

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The EDG set package is complete with Local control panel, AVR, gauges, starting

battery, excitation system other accessories within the EDG enclosure and a remote

GCP panel located within the MCC building SDCS room which contains the protective

relays and meters. The neutral of the DG set is solidly earth. The UPS DG set is

provided with facility for no load trial from the local control panel at the DG skid.

The DG set is provided with an inbuilt skid mounted fuel tank which receives fuel

supply from the 1250 kVA DG set fuel tank.

9.2.4 200 kVA UPS DG Set Operation & Control Philosophy:

DG Control – From UPS DG GCP

DG Protection – UPS DG GCP

DG Status Monitoring – UPS DG GCP/ SDCS


via Serial Link.

The UPS EDG GCP will house the protective relay of the EDG covering the following

protection functions:





9.2.5 200 kVA LQ DG Set Design (LQ-DG-01 at Living Quarter)

The 200 kVA LQ DG set is designed to feed power to the LQ emergency lighting in the

event of failure of the normal power to main lighting DB (MLSPDB-3500-01). On

sensing sustained under voltage on the normal incomer feeder of MLSPDB-3500-01,

200kVA LQ DG set starts automatically with an auto mains failure logic provided in

the AMF panel of the LQ DG set.

An ATS panel has been provided to feed power to MLSPDB-3500-01. ATS panel is

provided with 2 incomer MCCBs, one from transformer and other from LQ-DG-01. ATS

PLC includes necessary logics for changeover of one MCCB to other on receiving

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signals from GCP PLC. Electrical and mechanical interlock have been provided

between two MCCBs to prevent parallel operation of two incoming supplies of ATS

panel.

Under plant normal operating condition periodic no load test on the EDG set is to be

carried out by the operator to ensure the healthiness of the EDG set.

The LQ DG set package is complete with Local control panel, AVR, gauges, starting

battery, excitation system other accessories within the EDG enclosure and a remote

GCP panel located within the LQ Substation which contains the protective relays and

meter. The neutral of the DG set is solidly earth. The LQ DG set is provided with

facility for no load trial facility from the local control panel at the DG skid. The DG

set is provided with an inbuilt skid mounted fuel tank with manual filling facility.

9.2.6 200 kVA LQ DG Set Operation & Control Philosophy:

DG Control – From LQ DG GCP

DG Protection –LQ DG GCP

DG Status Monitoring –LQ DG GCP

The LQ EDG GCP will house the protective relay of the EDG covering the following

protection functions:





9.2.7 350 kVA Emergency DG Set Design (MHER-DG-01A & 01B at SGS Al Mahar)

SGS Al Mahar is provided with 2 nos. 100% rated 400V, 50 Hz, 350 kVA Diesel

Generator set working in one running one standby configuration. The diesel

generator set is designed to feed power to the AlMahr-0.4kV–SWG-01 to meet the

normal cum emergency power requirement of SGS Almahar as indicated in the

Electrical Load List- JI-191-EL-01-2970-10002

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Each of the EDG set packages is complete with Local control panel, AVR, gauges,

starting battery, excitation system other accessories within the EDG enclosure. In

addition a common remote GCP panel with separate sections for each DG controls

and common section for synchronizing facility located within the substation building

is provided which contains the DG controls, protective relays and meter for each of

the DG set.

The DG sets are also provided with synchronizing facility to permit synchronizing and

parallel operation of the sets. The synchronizing of the DG sets can be carried out by

the operator from the DG GCP panel at the substation building either in the auto

mode or in manual mode. The short circuit capacity of the AlMahr-0.4kV–SWG-01 is

rated for continuous parallel operation of the DG sets. The control logic within the

DG GCP panel is programmed for auto start of the standby DG set in the event of

failure of the operating DG set due to an electrical fault in the operating DG set. The

neutral of the DG sets are solidly earth. The DG set is provided with facility for no

load trial from the local control panel at the DG skid.

9.2.8 350 kVA Emergency DG Set Operation & Control Philosophy:

DG Control – From DG GCP

DG Protection – DG GCP

DG Status Monitoring – DG GCP / GTP SDCS via the DCS provided at the Almahar

substation


via Serial / Hardwired Link.

The EDG control panel will house the protective relay of the EDG covering the

following protection functions:





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9.3 6.6kV MV Switchboard (6.6kV-SWG-01 at GTP, Jihar)

9.3.1 6.6kV MV Switchboard Design:

6.6 kV MV Switchboard located at the GTP substation shall receive and distribute the

GTG/ Grid power to the entire plant. It is rated at 6.6 kV, 3ph, 50 Hz, 3150A, 50 kA

for 1 sec (Reference: JI-191-EL-13-2970-10002- 6.6kV Switchboard). The 6.6kV

Switchboard has been designed to allow the parallel operation of three generators at

part load in island mode of operation. In addition the 6.6 kV Switchboard has been

designed to allow the parallel operation of two generators with one of the grid

incomer feeder. Necessary mechanical interlock has been created in the 6.6kV

Switchboard to allow closure of only one grid incomer breaker at a time.

All the GTG‟s incomers, grid incomers, bus couplers and all the outgoing transformer

feeders are provided with vacuum circuit breakers in 6.6kV switchboard. All the

outgoing MV motor feeders in 6.6kV switchboard are provided with vacuum

contactors.

All the breakers of the 6.6kV switchboard are of identical rating (3150A) and

accordingly there is flexibility of using a spare breaker in case of fault to any of the

working breakers. All the vacuum contactors are of identical ratings (400A). However

inter-changeability between the contactor feeders is permitted with specific

attention to the fuse ratings associated with the particular motor rating.

9.3.2 6.6kV Switchboard Operating & Control Philosophy:

The 6.6kV Switchboard is envisaged to be operated as a continuous bus with all the

buscoupler breakers closed under all operating scenarios. However provision has

been made in the CSP panel for both dead bus closing and synchronising closing of

the buscoupler breakers.

Control – locally from 6.6kV Switchboard for transformer feeders / From CSP for

Generator and grid incomer feeders / From DCS/UCP for motor feeders.

Monitoring – at 6.6kV Switchboard / SDCS

Feeder Protection and Metering – at 6.6kV Switchboard

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Circuit breaker tripping is possible locally at switchboard in both test and service

positions of the breaker. However breaker close operation at the switchboard is

possible under test condition only (except for transformer and bus coupler breakers).

The control/selector switches provided on the switchboard shall include

Local/Remote selector switch, Trip/Neutral/Close breaker Control Switch.

Remote control of the incomer and outgoing breakers are envisaged under service

position of the breaker. The remote control of the GTG and Grid incomer breakers

and bus coupler breakers is from the Common Synchronising Panel for both breaker

closing and tripping operation. The remote control of the outgoing transformer

feeder is from the SDCS for both closing and tripping operations. The Motor

start/stop command from remote is initiated by the plant DCS/ package UCP/ LCS

for service position of the breakers as per the control philosophy indicated in the

respective P&ID. The DCS / UCP (as applicable) will also receive the Run, Stop, Trip

& Available status of all the MV motors from the SDCS.

Protection Relay provided in the 6.6kV switchboard shall include following:

For outgoing power transformers– composite numerical protective relays (Micom

P143) comprising of over current protection (50/51) and Earth fault protection (50G/

51G).

For outgoing motor feeders composite numerical relay (Micom P 242/243) comprising

of under voltage protection (27), extended start relay (48), over current protection

(50/51), Earth fault protection (50G/50Gs) and thermal overload protection. In

addition, the motors rated greater than 1500 kW (2 nos. Chiller motors and 3 nos.

Sales Gas Compressor motors) are provided with motor differential protection (87M).

For the generator incomer feeders protection will be provided by the 7UM 62 relay

at the GTG GCP. The P127 relay provided in the MV switchboard for the generator

incomer feeder will be used only for metering and breaker status communication to

SDCS.

For the grid incomer feeders – composite numerical protective relay (Micom P132)

comprising of over current protection (50/51) and Earth fault protection (50G/ 51G)

and reverse power protection (32).

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Metering on the MV switchboard shall include- Ammeter/voltmeter/ kW meter as per

single line diagram. The breaker status on the switchboard is provided with LED type

indication lamps.

The SDCS shall carry out the following control and status monitoring functions with

respect to the MV switchboard:

Closing/opening of all outgoing transformer breakers.

Status monitoring of all incomer and outgoing breaker/ contactor status.

Display of all important electrical system parameters including V, A, kW,

etc., of the 6.6 kV switchboard incomer and outgoing feeders.

Monitoring of the fault status from the output of intelligent relays provided in

the 6.6kV switchboard.

Recording and reporting of sequence of events (SOE) of outgoing feeders

including motor feeders and transformer feeders following a trip.

Transmitting of all motor status feedback (as required) to the DCS

Control Supply for the 6.6kV switchboard is 110V DC including the spring charging

motors. All 6.6kV breakers will trip automatically upon loss of 110V DC control

supply. The 6.6kV breaker feeders are also provided with an additional back-up trip

coil powered by 230V AC UPS.

9.3.3 Interlocks

Every feeder in the MV switchboard is provided with earth switch at the cable side of

the module. The operation of the earth switch is manual and it is interlocked

mechanically with the feeder breaker such that the earth switch can be closed only

if the associated breaker is open.

Each of the bus section of the MV switchboard is also provided with an earth switch

and interlocked electrically & mechanically with the bus coupler breaker so that the

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earth switch can be closed only if the associated bus coupler breaker and other

breakers in the bus section that can act as a power source to the bus are open. A

Ronnies Key interlock logic as described in Document No. JI-191-030076-DG-01-001

has been provided for the bus earthing of 6.6kV switchboard.

Mechanical Interlocks are created between the two grid incomer breakers to prevent

closure of both the grid feeders at the same time.

9.4 Distribution Transformers

9.4.1 2500kVA Transformer Design (2970-GTP-TR-01/02/03/04 at GTP, Jihar):

The GTP Substation has been provided with four nos. of 6.6 kV / 420 V, 2500kVA,

Dyn11, Z-6.25%, ± 5% OCTC, ONAN, conservator type, Distribution Transformers.

These Transformers are located outside the MCC building and shall cater to the LV

loads of the GTP area. 100% redundancy has been considered for calculating the

rating of these distribution Transformers.

9.4.2 2500kVA Transformer Operation and Control Philosophy:

Transformer feeder control – from 6.6kV Switchboard / from SDCS

Status Monitoring – at 6.6kV switchboard / SDCS

Transformer Protection – Thermal / Mechanical protection at Transformer and

electrical protection at 6.6kV Switchboard.

Under normal operating condition, two transformers (2970-GTP-TR-01/02) feed

power to Normal cum Emergency switchboard –PMCC-0.4kV-SWG-01 and two

transformers (2970-GTP-TR-03/04) feed power to the Normal process switchboard

PMCC-0.4kV-SWG-02. Two transformers feeding a particular switchboard will share

the total load of that switchboard at a given point of time. On failure of one of the

transformer, other healthy transformer will meet the total power requirement of the

switchboard.

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9.4.3 800kVA Transformer Design (2970-ADMIN-TR-01 at admin area):

The ADMIN area LV load is catered by one no. 6.6 kV / 420 V, 800kVA, Dyn11, Z-

6.25%, + 5% OCTC, ONAN, hermitically sealed type Transformer. The Transformer is

located outside the ADMIN Bldg. MCC Room and feeds power to ADMIN-PCC-01.






9.4.5 1600kVA Transformer Design (3500-LQ-TR-01 at LQ area):

The LQ area LV load is catered by one no. 6.6 kV / 420 V, 1600kVA, Dyn11, Z-4%, +

5% OCTC, ONAN, hermitically sealed type Transformer. The Transformer is located

outside the LQ Substation and feeds power to LQ-PMCC-01.






9.4.7 250kVA Transformer Design (3300-SGS-TR-01 at SGS Jihar):

The SGS LV load is catered by one no. 6.6 kV / 420 V, 250 kVA, Dyn11, Z=6.8%, + 5%

OCTC, ONAN, hermitically sealed type, Power Transformers. This Transformer is

located outside the SGS Jihar Substation and feeds power to SGS-PMCC-01.

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Transformer feeder control – from 6.6kV Switchboard / SDCS



electrical protection at 0.4kV Switchboard (SGS-PMCC-01) at SGS Jihar. In addition

an inter-trip to the MV breaker in case of a transformer fault at SGS Jihar via the

DCS of SGS and GTP has been provided.

9.5 LV Switchboards

The JIHAR stage-III LV three phase distribution system voltage has been selected as

400V. The LV switchboards are totally enclosed, metal clad, free standing, double

front (except for LQ-PMCC-01, SGS-PMCC-01 & ADMIN-PCC-01 switchboards which

will be single front) draw-out type with ACBs (except for GTG MCC‟s with incomer

isolators) for incomers and bus-couplers and MCCB‟s for outgoing motor/power

feeders.

9.5.1 PMCC-0.4kV-SWG-01 Design:

The 400V Normal Cum Emergency Switchboard (PMCC-0.4kV-SWG-01) is fed by two

transformer incoming lines, one from each 6.6 /0.420 kV, 2500 kVA distribution

transformers (i.e. 2970-GTP-TR-01 and 2970-GTP-TR-02) and a 1250 kVA DG incomer

connected via dual breakers . The switchboard consists of two bus sections (Bus-A &

Bus B) and a bus coupler breaker and various outgoing motor/ heater feeders and

power feeders. The rating of the switchboard is 4000A, 400V, 3 Phase, 4 Wire, 50

Hz, 80kA for 1 sec.

9.5.2 PMCC-0.4kV-SWG-01 Operation and Control Philosophy:

Control – locally from PMCC-0.4kV-SWG-01 for incomer transformer breakers, bus

coupler breaker and outgoing power feeders (in normal operation).

- from 1250 kVA DG GCP for DG incomer breakers, incomer transformer

breakers and bus coupler breaker ( under plant emergency operation).

- from DCS/UCP/ LCS for motor feeders.

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Monitoring – at PMCC-0.4kV-SWG-01 Switchboard & SDCS (via serial link).

Feeder Protection and Metering – at PMCC-0.4kV-SWG-01 Switchboard vide Discreet

Feeder vision relays (PB Gold) for outgoing MCCB feeders and motor vision relays (PB

Gold) for outgoing Motor feeder, Advanced Feeder Vision relays for incomer and Bus

couplers as detailed in the respective SLD.

Protection for EDG incomer feeders is located at EDG GCP.

During normal operation of the above switchboard, with the incoming lines healthy,

both the transformer incomers are in „closed‟ condition while the bus coupler is in

„open‟ condition. Local operation by the operator for transformer incomer and bus

coupler feeders is permitted in Test and service Position from the switchboard. In

the Local mode the breaker closing operation is performed by selecting Auto-

Independent-Manual (A-I-M) selector switch in Independent or Manual mode and the

Local/Remote (L/R) selector switch in „local‟ mode and close the breakers through

breaker control switch (TNC) at the switchboard.

Under the loss of any one of the main incoming supplies detected through under

voltage sensing at line voltage, the respective incomer, which has lost the supply

voltage, will „trip‟ and bus coupler will „close‟ automatically. The above change over

operation will take place if the Auto-Independent-Manual (A-I-M) selector switch

(located on Bus coupler panel) is in „Auto‟ position. Changeover is inhibited if the

incomer breaker has tripped on fault.

Under the restoration of the incoming supply at the incomer, which is open, A-I-M

selector switch shall be put to Manual mode and trip selector switch (TSS, on bus

coupler) shall be kept on Bus coupler position by the operator. L/R switch on second

incomer breaker to be put in „Local‟ mode. Now the operator to initiate the close

command of the second transformer breaker (this command will be routed through

synchro-check relay) and on closing of the second transformer incomer breaker, the

bus-coupler breaker will open automatically after momentary paralleling of two bus

sections. After achieving normal configuration of power supply to PMCC-0.4kV-SWG-

01 (transformer incomer breaker „close‟ and bus coupler „open‟), L/R switch to be

put in „Remote‟ position and A/I/M selector switch to be put in „Auto‟ position by

operator.

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Under loss of supply on both incomers (i.e. failure of upstream GTG/ Grid supply,

when grid supply is made available in future), incomer and bus coupler breakers will

trip automatically due to undervoltage condition. The 1250 kVA DG GCP will sense

this simultaneous undervoltage on the two transformer incoming feeders as a plant

emergency condition and it will initiate auto start of DG set provided the mode

selector switch in DG GCP is in Auto mode. Once the DG set is started and ready to

take load, the DG GCP will first provide close command to the bus coupler breaker to

ensure the PMCC-0.4kV SWG-01 is a continuous bus. Then it provides close command

to the DG breaker (the close command will be routed to one of the two DG CB based

on the position of the emergency CB selector switch on the DG GCP. Due to any

reason if the selected breaker fails to close then the DG GCP routes this command to

the second DG breaker) thus ensuring that the Emergency power is made available to

the switchboard.

Under the restoration of the incoming supply to any one of the transformer incomer

feeder, the DG GCP senses restoration of voltage on the incoming lines and initiates

the back paralleling sequence automatically after a time delay of 2 minutes (this

time delay has been introduced to avoid back paralleling under transient conditions).

On achieving synchronism between the DG and the transformer incomer feeder the

DG GCP initiates a close command to the transformer breaker thus allowing the DG

set to run in parallel with the main transformer supply with the DG sharing a

predefined set plant load. After a set time delay of 2 minutes, the DG GCP

automatically starts unloading of the DG set and trips the DG circuit breaker.

With the above, the entire PMCC-0.4kV-SWG-01 is being fed by one transformer

incomer feeder with the bus coupler breaker closed. For restoration of the second

transformer incomer feeder the A-I-M selector switch shall be put to Manual mode

and trip selector switch (TSS, on bus coupler) shall be kept on Bus coupler position

by the operator. L/R switch on second incomer breaker to be put in „Local‟ mode.

Now the operator to initiate the close command of the second transformer breaker

(this command will be routed through synchro-check relay) and on closing of the

second transformer incomer breaker, the bus-coupler breaker will open

automatically after momentary paralleling of two bus sections.

It is possible to trip all circuit breakers from the Switchboard irrespective of the

position of the Local/ remote selector switch, A/I/M switch position. The selection

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of local or remote control of breakers is made manually at the switchboard.

Monitoring is not affected by the position of the local/remote control switch. Lock

out relays can only be reset locally, and not from the remote position.

All outgoing power feeder control shall be local to the switchboard by the operator

both in test and service condition.

All outgoing motor/heater feeder control shall be from local in test position and

from remote LCS/ UCP/DCS based on the control philosophy described in the

respective P&ID. The DCS / UCP (as applicable) will also receive the Run, Stop, Trip

& Available status of all the LV motors / heaters from the SDCS.

9.5.3 PMCC-0.4kV-SWG-02 Design:

The 400V Normal Switchboard (PMCC-0.4kV-SWG-02) is fed by two transformer

incoming lines, one from each 6.6 /0.420 kV, 2500 kVA distribution transformers (i.e.

2970-GTP-TR-03 and 2970-GTP-TR-04). The switchboard consists of two bus sections

(Bus-A & Bus B) and a bus coupler breaker and various outgoing motor/ heater

feeders and power feeders. The rating of the switchboard is 4000A, 400V, 3 Phase, 4

Wire, 50 Hz, 80kA for 1 sec.

9.5.4 PMCC-0.4kV-SWG-02 Operation and Control Philosophy:

Control – locally from PMCC-0.4kV-SWG-02 for incomer transformer, bus-coupler

breakers and outgoing power feeders and from DCS/UCP/ LCS for motor/heater

feeders

Monitoring – at PMCC-0.4kV-SWG-02 Switchboard & SDCS (via serial link)

Feeder Protection and Metering – at PMCC-0.4kV-SWG-02 Switchboard vide Discreet

Feeder vision relays (PB Gold) for outgoing MCCB feeders and motor vision relays (PB

Gold) for outgoing Motor feeder, Advanced Feeder Vision relays for incomer and Bus

couplers as detailed in the respective SLD.

During normal operation of the above switchboard, with the incoming lines healthy,

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both the transformer incomers are in „closed‟ condition while the bus coupler is in

„open‟ condition. Local operation by the operator for transformer incomer and bus

coupler feeders is permitted in Test and service Position from the switchboard. In

the Local mode the breaker closing operation is performed by selecting Auto-

Independent-Manual (A-I-M) selector switch in Independent or Manual mode and the

Local/Remote (L/R) selector switch in „local‟ mode and close the breakers through

breaker control switch (TNC) at the switchboard.

Under the loss of any one of the main incoming supplies detected through under

voltage sensing at line voltage, the respective incomer, which has lost the supply

voltage, will „trip‟ and bus coupler will „close‟ automatically. The above change over

operation will take place when the Auto-Independent-Manual (A-I-M) selector switch

(provided on the bus coupler panel) is in „Auto‟ position. Changeover is inhibited if

the incomer breaker has tripped on fault.

Under the restoration of the incoming supply at the incomer, which is open, A-I-M

selector switch shall be put to Manual mode and trip selector switch (TSS, on bus

coupler) shall be kept on Bus coupler position by the operator. L/R switch on second

incomer breaker to be put in „Local‟ mode. Now the operator to initiate the close

command of the second transformer breaker (this command will be routed through

synchro-check relay) and on closing of the second transformer incomer breaker, the

bus-coupler breaker will open automatically after momentary paralleling of two bus

sections. After achieving normal configuration of power supply to PMCC-0.4kV-SWG-

02 (transformer incomer breaker „close‟ and bus coupler „open‟), L/R switch to be

put in „Remote‟ position and A/I/M selector switch to be put in „Auto‟ position by

operator.

It is possible to trip all circuit breakers from the Switchboard irrespective of the

position of the Local/ remote selector switch, A/I/M switch position.

All outgoing power feeder control shall be local to the switchboard by the operator

both in test and service condition.

All outgoing motor/heater feeder control shall be from local in test position and

from remote LCS/ UCP/DCS based on the control philosophy described in the

respective P&ID.

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9.5.5 The SDCS shall carry out the following control and status monitoring functions with

respect to the 0.4kV LV switchboard- PMCC-0.4kV SWG-01 & PMCC-0.4kV SWG-02:-

Display of all important electrical system parameters including V, A, kW, etc.

of the LV switchboard incomer and outgoing feeders.

Monitoring of the Available/Run/Fault/Stop status from the output of

intelligent relays provided in the LV switchboards.

Transmitting of all outgoing motor feeder status (as required) to the DCS

Recording and reporting of sequence of events (SOE) of feeders including

motor feeders and transformer feeders following a trip.

9.5.6 Interlocks

Intertrip of the transformer LV breaker on trip of transformer MV breaker is

provided.

Interlock between incomer and bus-coupler breakers to ensure Two-Out of

Three breakers remain closed at any point of time, with provision to defeat

the interlock during momentary paralleling of incomers.

Interlock between the two DG incomer breakers to ensure closure of only one

breaker at a time. (Applicable for PMCC-0.4kV-SWG-01 only).

9.5.7 0.4kV-Gas Gen-MCC-01/02/03 Design:

The 400V GTG MCC‟s (0.4kV-Gas Gen-MCC-01/02/03) are fed by dual incoming lines,

one from each of the bus sections (bus-A and bus-B) of PMCC-0.4kV-SWG-01. The

switchboard is a continuous single bus and feeds all the GTG 400V and 230V

auxiliaries. The rating of the switchboard is 800A, 400V, 3 Phase, 4 Wire, 50 Hz, 80kA

for 1 sec.

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9.5.8 0.4kV-Gas Gen-MCC-01/02/03 -Operation and Control Philosophy:

Control – Local from 0.4kV Gas Gen MCC-01/02/03 for incomer isolators and outgoing

power feeders and from GTG UCP for motor/heater feeders

Monitoring – at 0.4kV Gas Gen MCC-01/02/03 & SDCS (via serial link)

Feeder Protection and Metering – at 0.4kV Gas Gen MCC-01/02/03- Incomer isolator

with short circuit and overload protection provided at the upstream MCCB as

detailed in the respective SLD.

The dual incomer feeders of the GTG MCC are provided with isolators without any in-

built protection. The incomer feeder protection is provided on the upstream MCCB‟s

at PMCC-0.4kV-SWG-01. All outgoing motor feeders are provided with composite

numerical motor protection relay (PB Gold) and all outgoing MCCB power feeders are

provided with composite numerical feeder protection relay (PB Gold)

9.5.9 Interlocks

Mechanical Interlock between two incomer breakers.

Tripping of incomer breaker (isolators) of GTG MCCs in case of fault tripping

of upstream MCCB at PMCC-0.4kV-SWG-01 end.

9.5.10 ADMIN-PCC-01 Design:

The 400V Admin PCC (Admin-PCC-01) is fed by single transformer incoming line, from

6.6 /0.420 kV, 800 kVA distribution transformer (2970-ADMIN-TR-01). The

switchboard is a continuous single bus and feeds all the 400V and 230V auxiliaries in

the Admin building and all the areas around the Admin building including Ware

House, Truck Loading station, Fire station etc. The rating of the switchboard is

1250A, 400V, 3 Phase, 4 Wire, 50 Hz, 25kA for 1 sec.

9.5.11 ADMIN-PCC-01 -Operation and Control Philosophy:

Control – Local Control from the switchboard for incomer feeder and for all outgoing

power feeders.

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Monitoring – at ADMIN-PCC-01 / SDCS ( via hardwired signal for incomer feeder only)

Feeder Protection and Metering – at ADMIN-PCC-01.The incomer feeder of the Admin

PCC is provided with ACB and the incomer feeder protection is provided by Advanced

Feedervision relay. All outgoing MCCB power feeders are provided with composite

numerical feeder protection relay (PB Gold) as detailed in the respective SLD

9.5.12 LQ-PMCC-01 Design:

The 400V LQ PMCC (LQ-PMCC-01) is fed by single transformer incoming line, from 6.6

/0.420 kV, 1600 kVA distribution transformer (3500-LQ-TR-01). The switchboard is a

continuous single bus and feeds all the 400V and 230V auxiliaries in the LQ area. The

rating of the switchboard is 2500A, 400V, 3 Phase, 4 Wire, 50 Hz, 50kA for 1 sec. The

LQ PMCC feeds the LQ Lighting, HVAC and other miscellaneous loads of the LQ Area.

9.5.13 LQ–PMCC-01 -Operation and Control Philosophy:

Control – Local Control from the switchboard for incomer feeder and All outgoing

power feeders.

Monitoring – at LQ–PMCC-01 / SDCS ( via hardwired signal for incomer feeder only)

Feeder Protection and Metering – at LQ–PMCC-01. The incomer feeder of the LQ

PMCC is provided with ACB with inbuilt protective release. All outgoing MCCB power

feeders are provided with composite numerical feeder protection relay (PB Gold) as

detailed in the respective SLD

9.5.14 SGS-PMCC-01 Design:

The 400V SGS PMCC (SGS-PMCC-01) is fed by single transformer incoming line, from

6.6 /0.420 kV, 250 kVA distribution transformer (3300-SGS-TR-01). The switchboard

is a continuous single bus and feeds all the 400V and 230V auxiliaries in the SGS Jihar

area. The rating of the switchboard is 800A, 400V, 3 Phase, 4 Wire, 50 Hz, 25kA for 1

sec. The SGS PMCC meets the process and utility load requirements of the SGS Jihar.

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9.5.15 SGS-PMCC-01 -Operation and Control Philosophy:

Control – Local Control from the switchboard in for transformer incomer feeder and

all outgoing power feeders. The LV process motors and heaters Start / Stop control

is carried out either by Local Control Station or Package UCP or the plant DCS based

on the individual control philosophy described in the respective P&ID . The DCS /

UCP (as applicable) will also receive the Run, Stop, Trip & Available status of all LV

motors.

Monitoring – at SGS-PMCC-01 and SDCS (via serial link) for incomer feeder and

outgoing motor/heater feeders. ( The LV Switchboard incomer and outgoing feeder

status signal will be hardwired to the respective DCS at SGS Jihar and these signals

will be transmitted via fibre optic to the DCS at GTP and further transmitted via

serial link to the GTP SDCS).

Feeder Protection and Metering – at SGS-PMCC-01. The incomer feeders of the SGS

PMCC is provided with ACB with inbuilt protective releases. All outgoing MCCB

power feeders are provided with composite numerical feeder protection relay (PB

Gold) and all outgoing motor feeders are provided with composite motor protection

relay (PB Gold) as detailed in the respective SLD

9.5.16 Interlocks

Tripping of the transformer LV breaker on transformer fault . In addition an inter-

trip to the MV breaker in case of a transformer fault at SGS Jihar via the DCS of SGS

and GTP has been provided.

9.5.17 ALMAHR-0.4kV-SWG-01 Design:

The 400V Al Mahar PMCC (ALMAHR-0.4kV-SWG-01) is fed by dual 350 kVA DG sets

(MHR-DG-01A & 01B). The switchboard is a continuous single bus and feeds all the

400V and 230V auxiliaries in the SGS Al Mahar area. The rating of the switchboard is

800A, 400V, 3 Phase, 4 Wire, 50 Hz, 25kA for 1 sec. The Al Mahar PMCC meets the

process and utility load requirement of Al Mahar Area.

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9.5.18 ALMAHR-0.4kV-SWG-01 -Operation and Control Philosophy:

Control – Local Control from the switchboard of DG incomer feeder breakers.

Remote control from DG GCP panel of DG incomer feeders for dead bus closing /

synchronising closing of incomer breakers including live change over from one DG

incomer breaker to the other incomer breaker.

All outgoing power feeders control local to the switchboard.

All outgoing motor/heater feeder control from local switchboard in test position

and from remote LCS/ UCP/DCS in service based on the control philosophy

described in the respective P&ID.

Monitoring – at ALMAHR-0.4kV-SWG-01 and SDCS (via serial link) for incomer feeders

and outgoing motor/heater feeders (The LV Switchboard incomer and outgoing

feeder status feedback will be hardwired to the respective DCS at Al mahar and

these signals will be transmitted via fibre optic to the DCS at GTP and further

transmitted via serial link to the GTP SDCS).

Feeder Protection and Metering – at ALMAHR-0.4kV-SWG-01. The incomer feeders of

the Al Mahar PMCC are provided with ACB with inbuilt protective releases.

Protections related to DG are provided at DG GCP. All outgoing MCCB power feeders

are provided with composite numerical feeder protection relay (PB Gold) and all

outgoing motor feeders are provided with composite motor protection relay (PB

Gold)

9.6 Distribution Boards for Lighting, HVAC, Heat Tracing & Cathodic Protection

9.6.1 Lighting and Small Power Distribution Boards Design, Operation and Control

Philosophy (GTP Jihar, ADMIN, SGS Jihar, SGS Al Mahar, LQ and T4 Areas):

All indoor normal and emergency lighting and small power DB‟ will be classified as

safe area DB‟s. These DB‟s cater to the indoor and perimeter lighting and receptacle

loads of buildings. The DB‟s will be provided with MCCB incomer feeders and MCB

outgoing feeders. The incomer and outgoing feeders of these DB‟s will be controlled

locally by the operator. The perimeter lighting shall be controlled by photo cells and

these fixtures will be fed by the photo-cell bus section of the DB‟s.

The metering and status monitoring of these DB‟s are local to the panel.

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All outdoor normal and emergency lighting and small power DB‟ will be classified as

hazardous area DB‟s and located in the field area. These DB‟s cater to the outdoor

process, utility area and shelter lighting loads and outdoor welding receptacle loads.

The DB‟s will be provided with Isolators as incomer feeders and MCB outgoing

feeders. The incomer and outgoing feeders of these DB‟s will be controlled locally

by the operator. The outdoor process and utility area lighting shall be controlled by

photo cells and these fixtures will be fed by the photo-cell bus section of the DB‟s.

The metering and status monitoring of these DB‟s are local to the panel.

A common photocell has been provided for each of the plant area ( i.e. one photo

cell each at GTP/ LQ/ SGS/ Almahar/T4) and this photocell contact has been

multiplied and wired to the photo cell bus provided in the various indoor and

outdoor distribution boards.

9.6.2 Heat Tracing Distribution Boards Design, Operation and Control Philosophy (GTP

Jihar, SGS Jihar, SGS Al Mahar and LQ Areas):

All outdoor heat tracing DB‟ of GTP process area will be classified as

hazardous area DB‟s and located in the plant area. These DB‟s cater to the

heat tracing load requirement of process piping, instruments, vessels and

equipment as applicable. The DB‟s will be provided with Isolators as incomer

feeders and MCB +ELCB outgoing feeders. The incomer and outgoing feeders

of these DB‟s will be controlled locally by the operator. These DB‟s will be

provided with the common bus and winterisation bus sections . The common

bus section will be operated by the process maintained temperature and the

winterization will be operated based on the ambient temperature. The

metering of these DB‟s are local to the panel . The common trip alarm signal

of each of the GTP DB‟s will be hardwired to the SDCS and monitored both at

the SDCS and DCS. As the number of heat tracing circuits is very low for the

SGS, Al Mahar and LQ area, the heat tracing load is catered by the indoor

lighting and small power DB‟s .

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9.7 230V AC UPS System

9.7.1 230V AC UPS Design for Instrumentation, SDCS & Telecom System (230V-UPS-02,

GTP, Jihar):

1 No. 400V, 3- phase /230V, 1- phase, 50Hz, 2 x 100% parallel redundant AC UPS

system with 2 sets of rectifier/charger, battery bank, inverter, static transfer

switch, 1 set of bypass transformer and one separate distribution board is provided

in GTP Substation (UPS Room) to cater to Instrumentation, SDCS and Telecom system

loads.

The UPS units will operate in parallel and share the total load. The neutral of the

UPS system is solidly earthed. The rating of the AC UPS is 90kVA. The UPS have been

provided with VRLA batteries and battery back-up duration is for 8 hours. In addition

these UPS will be backed up by a standalone emergency DG set (in the event of the

main 1250kVA DG set fails to start and provide the required UPS input supply) rated

for the utilities connected to the UPS system in addition to charging current for

batteries provided the 200kVA DG set is started within a time frame of 15 mins. This

DG set will be provided with a local starting facility from local control panel of DG.

Main and bypass incomers of the UPS are fed from the normal–cum-emergency

switchboard (PMCC-0.4kV-SWG-01). Also DG power supply is provided for main and

bypass incomers of UPS through a supply-source changeover switch located at UPS.

Static Switches in the UPS ensure uninterrupted and synchronised switchover from

UPS supply to bypass in the event of mains failure or inverter/rectifier failure of

UPS.

The 230V AC UPS supply is distributed to the loads through 400V, 3- phase /230V, 1-

phase, 50Hz, 10kA for 1 sec, distribution board with two MCCB incomer feeders and

MCB outgoing feeders. The 230V AC UPS distribution board is located adjacent to the

UPS. Dual UPS supply is made available to all critical loads.

Mushroom Head type, pad lockable Exd-type safety pushbutton will be provided in

the battery room next to batteries for battery isolation.

AC UPS will generally be in compliance with Project Specification: GS-2210-60-00-20

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– Technical Specification for AC UPS

9.7.2 230V-UPS-02 Operation and Control Philosophy:

Controls: At respective 230 V AC UPS Panel

Status Monitoring: at UPS panel / SDCS (via serial link) / DCS

Protection: Integral to UPS.

Normal operation: Both units (UPS „A‟ and UPS „B‟) are connected in parallel to the

load and fed from 400V switchboard (PMCC-0.4kV-SWG-01).

Failure or switching off of any one of the rectifier: During this condition, the

healthy/active rectifier will supply both the inverters and keep charging both the

battery banks. Operation is automatic and without any output power supply

interruption.

Failure or switching off of both of the rectifiers or total loss of incoming power

supply: During this condition, the inverter will be supplied from the respective

battery banks for the autonomy time specified (8 Hrs.). However, it is envisaged to

make available alternate source of incoming power supply to UPS (i.e. main EDG or

in the event of failure of main EDG to start, UPS-DG-01).

Failure or switching off of any one of the inverters: During this condition, the entire

load is automatically transferred to healthy/active inverter unit, automatically and

without any output power supply interruption.

Failure or switching off of both inverters: During this condition, the entire load is

automatically transferred to bypass unit fed from PMCC-0.4kV-SWG-01. This

operation is carried out by static switches ensuring uninterrupted and synchronised

transfer.

9.7.3 230V AC UPS Design for Escape Lighting System (230V-UPS-04, GTP, Jihar):

1 No. 400V, 3- phase, 50Hz, single unit AC UPS system with 1 set of

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rectifier/charger, battery bank, inverter, static transfer switch, bypass transformer

and outgoing feeder to one separate distribution board is provided in GTP Substation

(UPS Room) to cater to escape lighting system.

The UPS will operate as a standalone unit. The neutral of the UPS system is solidly

earthed. The rating of the AC UPS is 22kVA. The UPS have been provided with VRLA

batteries and battery back-up duration is for 8 hours.

Main and bypass incomers of the UPS are fed from the normal–cum-emergency

switchboard (PMCC-0.4kV-SWG-01).




– Technical Specification for AC UPS.



Status Monitoring: at UPS panel / SDCS (via serial link).


Normal operation: UPS is fed from 400V switchboard (PMCC-0.4kV-SWG-01).

Failure or switching off of the rectifier or total loss of incoming power supply: During

this condition, the inverter will be supplied from the battery bank for the autonomy

time specified (8 Hrs.).

Failure or switching off of the inverter: During this condition, the entire load is

automatically transferred to bypass unit fed from PMCC-0.4kV-SWG-01. This


transfer.

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9.7.5 230V AC UPS Design for Instrumentation, DCS & Telecom System (230V-UPS-06, SGS,

Jihar):

1 No. 230V, 1-phase, 50Hz, 2 x 100% parallel redundant AC UPS system with 2 sets of

rectifier/charger, battery bank, inverter, static transfer switch, 1 set of bypass

transformer and one separate distribution board is provided in SGS, Jihar Substation

to cater to Instrumentation, DCS and Telecom system loads.



provided with VRLA batteries and battery back-up duration is for 8 hours for

instrumentation loads while 24 Hrs. back up is available for certain critical systems

like DCS, ESD and F&G loads.

Main and bypass incomers of the UPS are fed from the switchboard SGS-PMCC-01.

The 230V AC UPS supply is distributed to the loads through 230V, 1-phase, 50Hz,

10kA for 1 sec, distribution board with two MCCB incomer feeders and MCB outgoing

feeders. This DB have been provided with two buses, one (Bus-B) for catering to

loads with 8 Hrs. back-up and other (Bus-A) for catering to loads with 24 Hrs. back-

up. In the event of failure of normal power supply on both of the UPS incomers, a

timer in the DB will be activated which will provide a trip signal after elapsing of 8

hours to the bus coupler MCCB thus tripping of the bus-section-B . The 230V AC UPS

distribution board is located adjacent to the UPS. Dual UPS supply is made available

to all critical loads.







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Status Monitoring: at UPS panel / SDCS at GTP, Jihar (The UPS signals will be

hardwired to the respective DCS at SGS Jihar and these signals will be transmitted

via fibre optic to the DCS at GTP and further transmitted via serial link to the GTP

SDCS).



load and fed from 400V switchboard (SGS-PMCC-01).




interruption.



battery banks for the autonomy time specified (8 Hrs./24Hrs.).





automatically transferred to bypass unit fed from SGS-PMCC-01. This operation is

carried out by static switches ensuring uninterrupted and synchronised transfer.

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9.7.7 230V AC UPS Design for Instrumentation, DCS & Telecom System (230V-UPS-05, SGS,

Al Mahar):



transformer and one separate distribution board is provided in SGS, Almahar

Substation to cater to Instrumentation, DCS and Telecom system loads.



provided with VRLA batteries and battery back-up duration is for 8 hours.

Main and bypass incomers of the UPS are fed from the switchboard ALMAHR-0.4kV-

SWG-01.

The 230V AC UPS supply is fed to instrumentation PDB via two outgoing feeders for

further distribution to respective loads.








hardwired to the respective DCS at SGS Almahar and these signals will be transmitted

via fibre optic to the DCS at GTP and further transmitted via serial link to the GTP

SDCS).


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load and fed from 400V switchboard (ALMAHR-0.4kV-SWG-01).




interruption.



battery banks for the autonomy time specified (8 Hrs.).





automatically transferred to bypass unit fed from ALMAHR-0.4kV-SWG-01. This


transfer.

9.7.9 230V AC UPS Design for Instrumentation & Telecom System (230V-UPS-07, T4 area):



transformer and one integral distribution board is provided in T4 porta cabin to cater

to Instrumentation and Telecom system loads.



provided with VRLA batteries and battery back-up duration is for 4 hours.

Main and bypass incomers of the UPS are fed from distribution board T4-NDB-02.

The 230V AC UPS supply is distributed to the loads through integral 230V, 1- phase,

50Hz, 10kA for 1 sec, distribution board with two MCCB incomer feeders and MCB

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outgoing feeders.


the battery room next to batteries for isolation of batteries.






hardwired to the Instrumentation panel at T4 area and these signals will be

transmitted via fibre optic to the DCS at GTP and further transmitted via serial link

to the GTP SDCS).



load and fed from 400V distribution board T4-NDB-02.




interruption.



battery banks for the autonomy time specified (4 Hrs.).





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automatically transferred to bypass unit fed from distribution board T4-NDB-02. This


transfer.

9.8 110V DC UPS System

9.8.1 Design of 110V DC UPS (110V-DCP-03, GTP, Jihar) for Control supply of Switchgears :

The 110V DC UPS for electrical system will be Single unit type with single rectifier,

battery bank, blocking diodes included between rectifier and common DC bus and

integral distribution board. The DC UPS have been provided with VRLA batteries and

battery back-up duration is for 12 hours.

The control supply is provided to the following switchboards:

MV main Switchboard (6.6kV-SWG-01)

LV Switchboard incomer and bus-coupler breaker control supply (for PMCC-

0.4kV-SWG-01, PMCC-0.4kV-SWG-02, 0.4kV-GAS GEN-SWG-01/02/03, ADMIN-

PCC-01)

110V DC supply is sized to cater to the MV switchboard control, indication, metering

and protection function including operation of the breaker closing coil and tripping

coil. In addition it shall meet the DC supply requirement of LV incomer and bus-

coupler breaker closing and tripping coil.

Mushroom pad lockable Exd type safety pushbutton will be provided in the battery

room next to batteries for isolation of batteries.

DC UPS will generally be in compliance with Project Specification: GS-2210-60-00-17

– Technical Specification for Battery and Charger Assembly.

9.8.2 110V DC UPS Operation and Control Philosophy:

Controls: locally at 110V DC UPS Panel

Status Monitoring: Both at UPS panel and SDCS (via serial link)

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Protection: Integral to DC UPS

Normal operation: DC UPS is fed from 400V switchboard (PMCC-0.4kV-SWG-01).

Failure or switching off of the rectifier or total loss of incoming power supply: During

this condition, the DC load will be supplied from the battery bank for the autonomy

time specified (12 Hrs.).

10.0 PLANT OPERATION PROCEDURE - GTP

Operation of the plant electrical system is envisaged as Manual with most of the

control operation by the plant electrical operators. Accordingly the electrical system

is being designed for manual operation as far as possible.

10.1 Condition A - Plant Electrical System Start-Up Procedure on Island Mode of

operation

During initial start-up of the plant the following sequence of operations need to be

followed:

Step-1: Objective is to start the EDG for plant start-up

Operator to ensure that incomer breakers and outgoing breakers of the

Normal Cum Emergency Switchboard -PMCC-0.4kV SWG-01 are all open and

the bus coupler breaker is closed.

Start manually, the 1250 kVA Emergency Diesel Generator set (EDG-01) from

the EDG GCP.

When the DG set is ready to take load, energise the switchboard PMCC-0.4

kV-SWG-01 by closing the DG incomer breaker (I/C-2, Cubicle No.: 9F) or

(I/C-3, Cubicle No.: 12F) on to the dead-bus. The closing of the breaker is

automatic and from EDG GCP if DC-UPS power is available and is carried out

manually from the LV switchboard if the DC-UPS supply is not available.

Black Start: The EDG set can be started if the starting batteries are in fully

charged condition. The DG set is provided with 2 sets of starting batteries

and each of the starting batteries is rated for 3 start attempts in one hour.

In case the batteries are not charged, portable Genset of sufficient capacity

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need to be arranged by the company to charge the batteries for starting the

EDG set under black start conditions.

Once the Emergency DG set power is established to the PMCC-0.4kV SWG-01,

energise the outgoing feeder to auxiliary power to DG set.

Step-2: Objective is to energise all other emergency and critical process loads

connected to the Normal cum Emergency Switchboard PMCC-0.4 kV SWG-01 for plant

start-up.

Following critical loads on the Normal Cum emergency switchboard PMCC-0.4kV-

SWG-01 are to be started manually by the operator from the PMCC-0.4kV-SWG-01

switchboard.

Outgoing feeders to all Emergency Lighting Distribution Boards connected to

Emergency switchboard

Outgoing feeder to Auxiliary Power to DG

Outgoing feeder to MCC Building HVAC panel

Outgoing feeder to 230V- UPS-02

Outgoing feeder to 230V- UPS-04

Outgoing feeder to 110V-DCP-03

Additionally any or all of the following loads can be started, as per the plant black

start sequence:

Outgoing feeder to 0.4kV-GAS GEN- MCC-01 / 02 / 03 as applicable

Outgoing feeder to CP Rectifiers

Outgoing feeder to Heat tracing DB

Outgoing feeder to Small Power DB

All outgoing feeders those are required for GTG start-up from the GTG MCC

which has been energised to start the first GTG.

All outgoing feeders from 230V AC UPS Distribution boards

All outgoing feeders from 110V DC UPS Distribution board

Outgoing feeder to Potable Water Distribution Pump Motor

Outgoing feeder to other critical loads, if any

Based on the Process requirement the following Process loads can be started.

Outgoing feeder to Hot Oil Circulation Start-up pump

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Outgoing feeder to Instrument Air Compressor-A

Outgoing feeder to Fan Motor for Instrument Air Compressor A

Outgoing feeder to Enclosure Heater for Instrument Air Compressor A

Outgoing feeder to Fire Water Jockey Pump A

Outgoing feeder to Fire Water Tank Heater

Outgoing feeder to other critical process loads ( if any ) connected to the

PMCC-0.4 kV SWG-01 Emergency Switchboard

Step-3: Objective is to energise the 6.6 kV switchboard.

Energization of 6.6 kV Switchgear at the MCC Building: The dead bus closing of the

bus-tie AB and bus-tie BC from the common synchronising panel is to be carried out

manually. Operator to ensure that the 6.6 kV switchboard is a continuous bus with

all bus coupler breaker closed before starting of the GTGs under plant start-up

condition.

Identify and start one of the GTGs (either GTG-2841 or GTG-2842 or GTG-2843). The

feeders for the GTG-Auxiliaries shall be kept in ready to start condition, so that they

can start when the signals are received from the GTG-UCP. The GTG Auxiliaries are:

Starter Motor, AC Lube Oil Pump Motor, Main enclosure Vent Fan motor, Vent Air

filter bleed fan motor, Lube Oil Tank Heater, all 110V DC and 24V DC loads etc.

The first GTG is brought into circuit by dead bus closing of associated 6.6 kV incomer

breaker. The incomer circuit breaker close command in the GCP is executed by the

operator from common synchronising panel after ensuring that the NGR of the GTG

that is being brought into circuit is connected to the system, thus ensuring that the

6.6 kV system is earthed.

On closing of the first GTG incomer breaker on to the MV switchboard, the 6.6 kV

system gets energized and the 6.6 kV bus Voltage, kW and current feedback along

with breaker status is available to the SDCS.

Step-4: Objective is to energise the distribution transformers

On receipt of the above information, the operator can initiate manual closing of the

4 nos. 6.6 kV /0.42 kV, 2.5 MVA transformer (2970-GTP-TR-01 / TR-02/ TR-03/ TR-

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04) breakers either from the 6.6kV switchboard or from the SDCS panel and charge

the GTP distribution transformers.

Step-5: Objective is to switchover from the EDG supply to GTG power

On Energization of incoming line feeders of PMCC-0.4kV-SWG-01, back

paralleling sequence of the EDG with one of the transformer breaker will

take place automatically from the DG GCP (provided DG GCP is in Auto mode)

and on achieving of synchronism the closing of the selected incomer

transformer breakers will happen automatically (provided A/I/M selector

switch at the bus coupler panel is in Auto position and L/R selector switch is

in Remote position). Under this condition, the emergency DG set will be

operating in parallel with one of the transformers for a pre-defined time,

sharing the total load to a pre-defined set point. Under this circumstance one

of the transformer incomer feeder and EDG feeder will be operating in

parallel with the bus-coupler closed. After the pre-defined time the EDG will

de-load and trip automatically. Now the PMCC-0.4kV-SWG-01 is running with

the normal GTG power fed through transformer 2970-GTP-TR-01 and bus

coupler breaker closed.

After tripping of the 1250kVA EDG, the operator to initiate the close

command of the second transformer breaker (this command will be routed

through synchro-check relay) and on closing of the second transformer

incomer breaker, the bus-coupler breaker will open automatically after

momentary paralleling of two bus sections.

At this stage, the LV switchboard PMCC-0.4 kV SWG-01 is energised and is in normal

operation. Now all the balance loads of the switchboard can be brought into service.

Step-6: Objective is to energise the Process LV Switchboard – PMCC-0.4kV-SWG-02

On Energization of 2.5 MVA transformers (2970-GTP-TR-03 and TR-04),

operator to initiate manual closing of transformer LV breakers I/C-1 (Cubicle

No.: 16) and I/C-2 (Cubicle No.: 19) and energise the Normal Switchboard

with the bus-coupler breaker (Cubicle Nos.:17) kept open.

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Step-7: Objective is to start the second GTG and MV loads with pre-conditions of the

minimum power requirements:

With the Normal and emergency LV loads in circuit, the first GTG is partly

loaded. Based on the process operating requirement, the operator has to

decide on the starting of the second GTG. The MV motor loads are to be

started considering the running reserve capacity of the GTGs.

The minimum power required and the pre-conditions for starting of the large

motors including the Chiller motor and Sales Gas Compressor motors are as

defined in the Electrical System study report. The second GTG is brought into

circuit by the operator by initiating the auto-synchronising operation from

the common synchronising panel.

10.2 Condition B - Plant Electrical System Start-Up Procedure with the presence of

Grid supply (when grid supply is made available in future)

During initial start-up of the plant the following sequence of operations need to be

followed in the presence of Grid supply (when grid supply is made available in

future):

Step-1: Objective is to energise the 6.6 kV Switchboard.

The first step for the energising of the 6.6kV Switchboard is to ensure that the 110V

DC UPS system of GTP is commissioned and batteries are fully charged thus ensuring

control supply for the board. Next Operator to ensure that the 6.6kV Switchboard

incomer and outgoing breakers are open and operator to manually carry out the

dead bus closing of the bus-tie AB and bus-tie BC from the common synchronising

panel . Operator to ensure that the 6.6 kV switchboard is a continuous bus with all

bus coupler breaker closed before starting of the GTGs under plant start-up

condition. The grid incomer is brought into circuit by dead bus closing of the 6.6 kV

grid incomer breaker from the Common Synchronising panel. The incomer circuit

breaker close command in the GCP is executed by the common synchronising panel

after ensuring that the NGR of the grid incomer that is being brought into circuit is

connected to the system, thus ensuring that the 6.6 kV system is earthed. Only one

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of the grid incomer will be connected in circuit at any point of time and mechanical

interlock has been provided in the 6.6 kV switchboard to prevent closing of the two

grid incomer breakers at the same time taking into account the fault current

limitation of 50kA on the offered switchboard.

Step-2: Objective is to energise the power transformers to ensure start-up power for

the GTG auxiliaries

On closing of the grid incomer breaker on to the MV switchboard, the 6.6 kV system

gets energized and the 6.6 kV bus Voltage, kW and current feedback along with

breaker status is available to the SDCS

On receipt of the above information, the operator can initiate manual closing of the

4 nos. 6.6 kV /0.4 kV, 2.5 MVA transformer (2970-GTP-TR-01 / TR-02/ TR-03/ TR-04)

breakers either from the 6.6kV switchboard or from the SDCS panel and charge the

GTP distribution transformers.

On charging of transformers, operator to manually close the LV breakers of 2970-

GTP-TR-01 and 2970-GTP-TR-02 with bus-coupler breaker open to energise PMCC-

0.4kV-SWG-01.

Step-3: Objective is to energise all emergency and critical process loads connected

to the Normal cum Emergency Switchboard for plant start-up as per Step 2 of Clause

10.1.

Step-4: Objective is to start the plant GTG‟s

Identify and start one of the GTGs (either GTG-2841 or GTG-2842 or GTG-

2843). The feeders for the GTG-Auxiliaries shall be kept in ready to start

condition, so that they can start when the signals are received from the GTG-

UCP. The GTG Auxiliaries are: Starter Motor, AC Lube Oil Pump Motor, Main

enclosure Vent Fan motor, Vent Air filter bleed fan motor, Lube Oil Tank

Heater, all 110V DC and 24V DC loads etc.

The first GTG is brought into circuit by synch closing of its 6.6 kV incomer

breaker to the 6.6kV Switchboard. The incomer circuit breaker close

command in the GCP is executed by the common synchronising panel after

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ensuring that the NGR of the grid incomer is connected to the system, thus

ensuring that the 6.6 kV system is earthed.

Now one GTG and the grid supply will be operating in parallel and will be

sharing the load based in the load sharing set values provided in the SDCS

system. During load sharing between the GTG and the Grid, the grid will

make available the instantaneous short fall of power on the system based on

instantaneous load demand and the amount of power to be delivered by the

GTG will be controlled by SDCS based on 4-20mA reference signal.

Based on the process load requirement the operator to decide on the start of

the second GTG if required similar to the starting procedure followed for the

first GTG. Under this condition two GTG‟s and the grid supply will be

operating in parallel and will be sharing the load based in the load sharing

set values provided in the SDCS system. During load sharing between the

GTG and the Grid, the grid will make available the instantaneous short fall of

power on the system based on instantaneous load demand and the amount of

power to be delivered by the GTG will be controlled by SDCS based on 4-

20mA reference signal.

Step-5: Objective is to energise the Normal LV Switchboard PMCC-0.4 kV SWG-02

On synch closing of the GTG incomer breaker on to the MV switchboard, the

6.6 kV bus Voltage, kW and current feedback along with breaker status is

available to the SDCS. On receipt of the above information, the operator

either manually from 6.6kV switchboard or remotely from the SDCS initiates

the closing of the 2 nos. distribution transformers ( 2970-GTP-TR-03 and 04)

LV breakers feeding the 0.4 kV normal switchboard and charge the PMCC-

0.4 kV-SWG-02 with the bus-coupler breaker (Cubicle Nos.:17) kept open.

Now the PMCC-0.4kV-SWG-02 is running with the normal GTG/ Grid power

fed through transformers 2970-GTP-TR-03 and 04.

At this stage, all the main LV switchboards –PMCC-0.4kV-SWG-01 and PMCC-0.4kV-

SWG-02 are energised and in normal operation. The LV loads of Process and utility

can be started and the plant will continue operation under 1 Grid supply & 1 or 2

GTG operating configuration.

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Step-6: Objective is to start MV loads with pre-conditions of the minimum power

requirements.

With the Normal and emergency LV loads in circuit, and the load shared

between the GTG and grid supply based on the pre-defined set points, the

GTG‟s will be partly loaded. The MV motor loads are to be started

considering the running reserve capacity of the GTGs and grid power import

set point

The minimum power required and the pre-conditions for starting of the large

motors including the Chiller motor and Sales Gas Compressor motors are as

defined in the Electrical System study report.

10.3 Condition C- Plant Normal Operating Condition - GTP

The various normal operating scenarios of the plant are:

Scenario 1 - 2 GTG‟s operating in parallel without grid connection .

Scenario 2 - 3 GTG‟s operating in parallel without grid connection.

Scenario 3 - 1 GTG operating in parallel with the grid connection.

Scenario 4 - 2 GTG‟s operating in parallel with the grid connection

Under plant normal operating condition, based on the above selected

operating scenario the connected GTG‟s / Grid will feed input power to the

6.6 kV MV Switchboard.

All the bus-coupler breakers of the MV Switchboard are closed and the MV

Switchboard will operate as a continuous bus.

All the outgoing transformer breakers of the MV Switch board are in circuit,

feeding power to the plant LV normal and emergency switchboards and the

normal loads of LQ and SGS Jihar.

The outgoing MV motor feeders are in circuit based on the process operating

conditions.

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The outgoing LV normal and emergency power and motor feeders are in

circuit based on the process operating conditions.

The Emergency DG is under standby condition.

The 230 V AC UPS are energized and continuously feeding the instrument,

telecom and the SDCS and escape lighting loads of the plant.

The 110 V DC UPS is energized and will feed the breaker control supply of the

MV & LV Switchboard as defined.

The 110V DC and 24V DC System of the each of the three GTGs are energized

and feeding the critical loads of the GTGs.

10.4 Condition D - Plant Abnormal Operating Condition -GTP

Situation-1 – Tripping of one of the GTG’s due to fault.

Under plant normal operating condition, when one of the GTGs trips on fault, the

full operating load of the plant will come on the other operating generators / Grid

connection depending upon the Plant operating scenario at that given point of time.

Scenario 1 - 2 GTG’s operating in parallel without grid connection.

Under this scenario, the total plant operating load will come on the one operating

generator.

a) In order to sustain the plant with the one operating generator, it will be

required to limit the load on the 6.6 kV bus to the capacity of the operating

generator set point ( i.e. 9MW at 45 deg C). For this, bulk load shedding will

be required, adopting a fast load shedding scheme and the same will be

achieved using df/dt function and fixed frequency setting of the numerical

relays provided on the 6.6kV bus.

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b) The estimated maximum load on the plant works out to be 15.58 MW

(including 4MW Phase-2 load). On loss of one generator the total load of the

plant is required to be restricted to the capacity of one operating generator

i.e. 9MW and accordingly the following loads will be tripped immediately to

limit the power consumption to one of the operating GTG‟s whilst still be

able to continue with the plant process partially :-

- Priority-1 – Outgoing Tie Feeder to Phase -2 (4MW)

- Priority-2 - Outgoing Transformer feeder to Administration PCC & to LQ PMCC

(1.67MW)

- Priority – 3 - Recycle Compressor Motor (1.22MW)

With the above motors / feeders tripped, the total load on the system is

restricted to less than 9 MW and the same will be met by the one operating

GTG.

Based on the transient stability study, the above load shedding is required to

be carried out within a time period of 500ms to avoid sustained under

voltage/ under frequency condition on the 6.6kV bus leading to tripping of

the other operating generator causing a complete plant shutdown.

Scenario 2 - 3 GTG’s operating in parallel without grid connection.

Under this scenario, the total plant operating load will come on the

remaining two operating generators which will still be able to meet the total

plant load requirement without any interruption in supply.


Under this scenario, the available power from the grid will be around 10 MW

(i.e. considering a 12.5 MVA transformer).

The following loads will be tripped immediately to limit the power

consumption to the grid transformer output whilst still be able to continue

with the plant process :-

- Priority-1 – Outgoing Tie Feeder to Phase -2 (4MW)

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Priority-2 - Outgoing Transformer feeder to Administration PCC & to LQ PMCC

(1.67MW)

With the above feeders tripped, the total load on the system is restricted to

less than 10 MW and the same will be met by the one operating grid

transformer.

Scenario 4 - 2 GTG’s operating in parallel with the grid connection.

Under this scenario, the total plant operating load will come on operating

generator and the grid supply, which will be able to meet the total plant

load requirement without any interruption in supply.

Situation-2 – Tripping of one grid incomer due to fault.

During plant normal operation only one of the grid incomer feeder will be in circuit

due to the mechanical interlock provided on the MV switchboard which ensures only

one grid breaker will be closed at any point of time. Under plant normal operating

condition, when the connected grid incomer trips on fault, the full operating load of

the plant will come on the other operating generators depending upon the Plant

operating scenario at that given point of time.

Scenario 1 - 2 GTG’s operating in parallel with the grid connection.

Under this scenario, the total plant operating load will come on to the two

operating generator which will be able to meet the total plant load

requirement without any interruption in supply.


Under this scenario, the total plant operating load will come on the one

operating generator and the operations as detailed under Clause 10.4

Condition-D, Situation-1, Scenario-1 will be repeated.

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Situation-3 – Tripping of one of the large Motors (Sales Gas Compressor Motor or

Chiller motor) due to electrical fault.

a) Under plant normal operating condition with two GTGs feeding the plant

loads or 1 GTG with 1 grid supply feeding the plant loads, when one of the

large motor – i.e. the Sales gas compressor motor or the Chiller motor trips,

a sudden load throw off condition is sensed by the 6.6 kV System.

a) The MV Switchboard will sense an over voltage/ over frequency condition.

The Control system of the GTGs- which are all operating in parallel and

communicating to each other, will sense an over voltage/ over frequency

condition of the 6.6 kV System due to the generation being more than the

demand. Accordingly the GTG control system will reduce the output from the

operating GTGs by going into droop mode of operation. The imbalance caused

during the transient period is within acceptable limits.

b) On loss of one of the large motors, the DCS/Package UCP shall take up

control of the process by tripping / closing of the necessary loads based on

the plant process operating philosophy.

c) Operator shall study the Electrical Fault Sequence of Events (SOE) recorded

at the SDCS causing the tripping of the large Motor on fault. Based on the

type of fault, the operator shall decide if the fault is major or minor.

d) If minor, the fault shall be cleared by the operator in minimum time, keeping

the two generators in operation on reduced load. On clearance of the fault

the large motor shall be brought into circuit by the operator via LCS/ DCS/

package UCP at the specified loading conditions with base load as defined by

the system study report.

Situation-4 – Sustained Overload Condition on the Running system

a) During plant normal operation, the total calculated running load on the

system is as per Electrical Load Schedule (JI-191-EL-01-2970-10002 & JI 191-

EL-06-4300-10002). Based on the present load list the total Jihar Phase-3

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plant operating load shall be met by two operating generators or 1 generator

& 1 grid supply under all operating conditions.

b) During sustained overload on the system, as monitored by the SDCS, the

Operator can initiate the starting of the third GTG (under 2 GTG & No grid

operating scenario), if time permits. Else the operator shall initiate the

tripping of non critical loads to maintain the load within the generation

capability of the two GTGs. The tripped loads can be brought back into

circuit by the operator after starting of the 3rd GTG.

c) Under the operating scenario of 1 GTG & 1 Grid, any shortfall of power will

be met by the grid by making appropriate setting of power to be drawn from

the grid at the SDCS by the operator.

Situation- 5– Tripping of the Distribution Transformers feeding the bus-section-A /

B of LV Switchboards – PMCC-0.4kV-SWG-01 or PMCC-0.4kV-SWG-02.

a) On Loss of supply to bus-section A or B of either PMCC-0.4 kV-SWG-01 or

PMCC-0.4 kV-SWG-02, under voltage condition is sensed by the auto change

over logic of switchboard which will initiate an auto change-over, enabling

the closing of the bus coupler breaker thus resuming power to the entire

switchboard from the healthy transformer.

In case of failure of auto-transfer the affected bus section load will loose

power and an alarm will be generated.

On loss of supply to both bus sections A & B of PMCC-0.4kV-SWG-01, an under

voltage condition is sensed by the 1250 kVA DG GCP thus implying loss of

main power from the GTG / Grid supply. The 1250 kVA DG GCP will initiate

an auto start of the DG set

b) The EDG is expected to energise and brought into circuit in approx. 20

seconds. The breaker closing operations to ensure power to the Normal cum

emergency switchboard is carried out by the EDG GCP panel without the

intervention of the operator. The tripping of the transformer incomer

breakers 2970-GTP-TR-01 and 02 on under voltage condition will happen

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automatically at the switchboard to prevent back feed of power from the

Emergency DG to 6.6kV Switchboard. On tripping of the Transformer incomer

breakers, the DG GCP will initiate the closing of the bus coupler breaker of

PMCC-0.4kV-SWG-01 to ensure the switchboard operates as a solid bus and

ensuring emergency power is made available to all the emergency loads

connected to Bus-A and Bus-B. With this critical emergency loads at the

Normal cum Emergency switchboard PMCC-0.4kV-SWG-01 is catered by the

EDG set via the power feeders that will remain closed even on loss of Main

GTG power.

c) Once the operator has established and cleared the fault that caused the GTG

tripping, the two running GTGs are brought back into circuit by following the

applicable steps of Condition-A. In the event of a major fault on the tripped

generator, then the operator has to establish the process power requirement

by bringing in the one healthy generator and standby generator into circuit.

d) Under the back paralleling sequence the DG GCP will initiate synchro closing

of one of the transformer incomer breaker (either 2970-GTP-TR-01 or TR-02

based on the priority selection at GCP) with the DG breaker. Once the

transformer breaker is closed, the 1250 kVA EDG and the 2500kVA

transformer will be operating in parallel with the bus coupler breaker closed

and feeding power to the entire normal cum emergency board. The EDG will

share the load with the transformer to a predefined set point and will run in

parallel for a predefined set time of 2 minutes. After this preset time the

EDG GCP will initiate the unloading of the DG set and tripping of the DG

incomer breaker automatically. Now the entire PMCC-0.4kV-SWG-01 is being

fed by one of the distribution transformer with the bus coupler breaker

closed. Now the operator shall initiate the synchro closing of the second

transformer incomer breaker from local to the switchboard by placing the

trip selector switch in the bus-coupler position. With this synchro closing of

the second transformer incomer breaker the bus coupler breaker will be

tripped as per two out of three breaker logic. Operator to note that only

momentary short time parallel operation of the DG set with the distribution

transformer is envisaged due to the fault level restriction of the PMCC-0.4kV

SWG-01 as highlighted in short circuit study report.

electrical operating philosophy ji 191 el 08 0000 10006 rev 0

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