Electrical design basis for electrical system at manned stations




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ELECTRICAL DESIGN BASIS FOR ELECTRICAL SYSTEM AT MANNED STATIONS

CONTENTS



1. SITE CONDITIONS
2. POWER SOURCE DETAILS
3. POWER SUPPLY DISTRIBUTION SYSTEM
4. PROTECTION - METERING - CONTROL
5. SUBSTATION DESIGN
6. EQUIPMENT DESIGN
7. CABLING SYSTEM
8. EARTHING SYSTEM
9. LIGHTING SYSTEM
10. ELECTRIC HEAT TRACING SYSTEM
11. ELECTRICAL EQUIPMENT FOR HAZARDOUS AREAS
12. STATUTORY APPROVAL
13. CABLE SIZES FOR MV MOTORS
14. SPECIFIC REQUIREMENTS (IF ANY)
The electrical design data defines the design requirements (Data marked ‘*’ shall be furnished/ confirmed by as per site conditions).

  1. Site conditions

A. Equipment design temperature (IS 9676) : 45 °C

B. Soil Resistivity : Later (*)

C. Minimum temperature. : 10 °C

D. Seismic zone( IS-1893) : As per IS 1893

E. Altitude above mean sea level : *

. Atmosphere : *

  1. Power Source Details

    1. General



  1. 6.6 kV/3.3 KV 3Ph.,50Hz as applicable/available

2.2 Power Supply: *

Location

Name of S/S

Number of feeders

Length of feeder/

Cond. size

Voltage

Min./Max fault level

Design Fault level/

BIL

System Neutral Earthing



















































































































A. Name of substation : As per Table above

B. Number of feeders : As per Table above

C. Length of feeder / conductor size : As per Table above

D. Voltage : As per Table above

E. Frequency : 50 Hz ± 3 %

F. Min/max fault level : As per Table above

G. Design fault level / BIL : As per Table above

H. System neutral earthing : As per Table above

I. Minimum load p.f. stipulated by : 0.9*

supply authority

J. Parallel operation of incomers : Yes/No

2.3 CPP and its configuration

A. Number / type of captive generators :

B. Rating of each generator :

C. Parallel operation with grid :

D. Neutral earthing :



    1. 2.4 Emergency generator

A. Number / type of emergency generator : 1 / Diesel

B. Generator rating :

Location

Rating

Voltage Level

Remarks







415V

Rating may change as per the actual load requirement & shall be decided during detailed engineering

C. Starting : Both Auto (through AMF

Panel) and manual modes

D. Short time paralleling with grid system: No



                1. Power Supply Distribution System

    1. Voltage and frequency variation

(Refer clause 6.6 for design voltage/frequency variation for motors)

A. AC System

Voltage HV : + 10%

MV : + 10%

Frequency : + 3%

  1. DC System (at system output terminals)

Electrical Control, Lighting etc. : + 10%

Instrumentation Power Supplies : + 10%

3.2 Utilisation voltage & operating philosophy







A.

HV(incoming) voltage :

B.

HV distribution system neutral earthing

C. HV motor voltage :

D. Auto transfer at H.V : Yes/No

E. Auto transfer at MV : Yes /No

F. Continuous Parallel operation of Incomers

- HV : Yes/No

- MV : Yes/No

G. Load shedding : Yes/No

H. MV motor voltage (415 V AC) : *

I. Power factor improvement Capacitors : *

J. Battery Chargers : 415 V AC

K. UPS System : 415 V AC

L. AC Lighting/Power Panels and : 415V AC

Auxiliary Boards

M. Welding Receptacles : 415V AC

N. Bulk loads like Process Heaters etc. : *

O. Normal Lighting/Emergency Lighting : 240V AC

P. Motors rated below 0.18 kW : 240V AC

Q. Convenience outlets : 240V AC

R. DC Motor : *

(e.g. emergency lube oil pump motor etc.)

S. MOVs : 415V AC except for First

valve after Flow tee,

which shall be fed from

230V,1-Ph AC UPS

Power supply.

3.3 Utilisation voltage for critical supplies

A. Normal Instrumentation power supply : 230 V AC

B. Critical instrumentation power supply : 230 V AC (UPS)

C. Shut-down system power supply : *

D. Switchgear protection power supply

and Critical lighting power supply : 110 V DC

E DC supply for SCADA : As per manufacturer

Through rectifiers

F. DC power supply for Communication/Telecom : (-)48V DC through

System rectifiers

G. Fire alarm system power supply : 230V,1-Ph,AC(UPS

Power with battery back-up of suitable voltage rating)

H. SCADA Remote workstations power supply :230V,1-Ph.AC UPS

I. Telecom AC power supply : 230V,1-Ph AC UPS;

230V,1-Ph AC Non UPS

J. CP system : 230V,1-Ph AC UPS

  1. Protection - Metering – Control

4.1 Metering for external power supply incomers :

A. Summation metering : If required

B. Trivector meter : If required

C. Phase sequence indicator : required

4.2 Control Philosophy

A. Protection relays for HV switchgear : On switchgear

B. Switchgear control : From Switchgear

C. Annunciation panel : at Switchgear room

D. Numerical Protection/Monitoring system for

i) EHV system : No

ii) HV Switchboard : Yes (for protection and monitoring)

iii) 415V PMCC/PCC : Yes (55kW & above motor feeder and in breaker incomer & B/C (in case of auto changeover))

iv) 415V MCC : No

Microprocessor based system for control : As applicable

Interlocking and monitoring of electric power

System

  1. Limiting Conditions for Motor start up

(e.g. starting current limitation or method of starting)

i) HV Motors : For HT motors on DOL/VFD

ii) MV Motors : For LT motors on DOL/VFD

G. Isolation for remote transformers: As applicable

4.3 Protection devices for power distribution system shall be as indicated below:

Requirements for DG shall be as per Cl.14.0 of this document or as shown on the single line diagram.

Relay number

Transformer

Feeder

Motor feeder

Outgoing feeder

Incomer




(Sec. winding > 3.3 KV)


(Sec . winding < 0.433 KV)


HV


HV


MV PCC/

PMCC


HV


MV PCC/

PMCC


51 IDMTL over-current relay


Yes


Yes


-


Yes


Yes

(4)


Yes

(12)


Yes (4)


51N IDMTL earth-fault relay


Yes (7)


No


-


Yes


Yes

(4)


Yes

(12)


Yes


51G backup earth-fault relay (secondary neutral)


Yes


Yes


-


No


No


No


No


Motor protection numerical relay with locked rotor feature (50, 50N,

46, 49, 50L/R)


No


No


Yes


No


Yes (8)


No


No


64R instantaneous restricted earth-fault relay (secondary side)


Yes


No


-


No


No


No


No


50 instantaneous over-current relay


Yes


Yes


-


No


No


No


No


50N instantaneous earth-fault relay


Yes (6)


Yes


-


No


No


No


No


87 differential protection relay


Yes (1)


No


Yes (2)


Yes (3)


No


No


No


86 tripping relay


Yes


Yes


Yes


Yes


Yes


Yes


Yes


95 trip circuit supervision relay


Yes


Yes


Yes


Yes


No


Yes


Yes, for breaker fdr.



63 transformer auxiliary relay


Yes


Yes


-


No


No


No


No


27,2 under-voltage relay with timer


-


-


No

(13)


-


-


Yes (5)


Yes (5)


25 check synchronisation relay


-


-


-


-


-


Yes(9)


Yes(9)


80 DC Supply supervision relay


-


-


-


-


-


Yes (14)


Yes (14)

NOTES:

  1. For transformers rated 5 MVA and above.

  2. For motors rated 1500 kW and above.

  3. For critical/long feeders and plant feeders connected to main power generation and distribution bus.

  4. VOID

  5. Wherever auto-transfer feature is provided.

  6. Instantaneous earth fault 50N shall be provided only for transformer with delta primary.

  7. Directional IDMTL earth fault 67N shall be provided for transformer with star primary.

  8. For motor feeders rated fed from PCC.

  9. For switchgears having bus transfer scheme, where continuous or momentary paralleling is envisaged, check synchronising relay shall be integrated with overall paralleling scheme.

  10. The bus tie feeders in HV switchboards shall be provided with 51, 51N, 86 and 95 relays.

  11. VOID

  12. VOID

  13. The following feeders shall be provided with timers for delayed tripping on bus under voltage while the under voltage relay shall be common for the bus

  14. HV and MV capacitor feeders

  15. HV and MV breaker controlled motor feeders or contactor feeders with DC control supply.

  16. One no. DC supply supervision relay (80) shall be provided for each incoming DC supply to the switchboard.

  17. VOID

  18. O/V relay (59) will be provided at 415V PCC bus to trip capacitors in case of over voltage.

4.4 Metering

The metering devices in HV and MV switchboards shall be as below :


Feeder Type


A


V


Hz


PF


MW


MWH


Hour Run


MVAR


MVAH


MVA


HV Incomer


X


X


X


X


X KW (see note-1)

X KWH


-


-






HV Bus Tie


X


-


-


-


-


-


-


-


-


-


HV Transformer


X


-


-


-




X

KWH


-


-


-


-


HV Bus P.T.


-


X


-


-


-


-


-


-


-


-


HV Plant Feeder


X


-


-


-


-


X

KWH


-


-


-


-


HV Motor


X


-


-


-


-


X

KWh


X


-


-


-


HV Capacitor


X


X


-


-


-


-


-




-


-


PCC/PMCC Incomer


X


X


-


X


-


X

KWh


-


-


-


-


PCC/PMCC Bus Tie


X


-


-


-


-


-


-


-


-


-


PCC Bus P.T.


-


X


-


-


-


-


-


-


-


-


ACB Outgoing


X


-


-


-


-


X

KWh


-


-


-


-


MV Motor (>75kW)


-


-


-


-


-


-


-


-


-


-


MCC/ASB Incomer


X


X


-


-


-


-


-


-


-


-


MCCB/SFU O/G(250A)


X


-


-


-


-


X

KWh


-


-


-


-


LDB Incomer


X


X


-


-


-


-


-


-


-


-


DG Set


X


X


X


X


X

kW


X

KWh


X


-


-


-

NOTE:

    1. KW meters shall be provided for only external Incomer feeders.

    2. Field Ammeters are to be provided for all motors rated above 5.5 kW. The field ammeter shall be analog.

    3. Transducers with 4-20mA output signals for following shall be provided in switchboards for remote monitoring on SCADA through PLC :-

kWH and current for incomer feeders of main HT switchboards

      • kWH and current for outgoing feeders to booster pump motors and mainline pump motors.

5 Substation Design

5.1 EHV Switchyard :

A. Bus bar :

B. Structure :

C. Bus material :

D. Incomer lines :

E. Voltage :

F. Current :

HV/MV Substation


Substation Details


HV


MV


Elevated with trays in cable cellar


Yes


Yes


Raised with internal trenches


Yes


Yes


All top cable entry with trays below ceiling


No


No


Pressurisation against ingress of dust


Yes/No


Yes/No


Air-conditioned room for operator


Yes/No


Yes/No

Cable inside the existing substation if any shall be laid in built in cable trench.

Transformer roof : Yes/No

5.3 Specific Equipment Locations

A. Batteries

Electrical switchgear batteries : Inside substation

UPS batteries : battery room in the Control Room

B. Battery charger : Inside substation

C. Variable speed drive panels : CR/SS as applicable/suitable with AC

D. UPS System : Air conditioned room in control room

E. Lead-Acid and Nickel- :

Cadmium batteries in separate rooms

F. Annunciation panel :

                6 Equipment Design

6.1 EHV Switchyard :

A. Bus bar system : Single/Double

B. Circuit breaker type : Minimum oil/SF6

C. Isolator type : Pantograph/Semi pantograph/

Centre rotating/ Centre break

6.2 HV Switchboard

A. Execution : Drawout /Fixed

B. Bus bar : Single /Double

C. Circuit breaker type : SF6/Vacuum *

D. Motor Control : Breaker

E. Separate MCC : Yes/No

6.3 Current Transformer (CT)/potential Transformer (PT)

A. CT Secondary

- Protection : 5A/1A, 15VA (1A for unit protection

and 5A for motor protection)

- Metering : 1A

B. PT Secondary : 110 V AC



    1. Transformers (Power/distribution) : NA

Transformer

Vector group

Tap changer

Soak pit

Preferred rating (kVA)


















    1. MV Switchboard

A. Execution

i) PCC / PMCC

Breaker panels : Draw out/Single front

Contactor feeders : Drawout, Double front

ii) MCC : Drawout : Double front(if

applicable)

iii) ASB :

iv) LDB :

v) Motors

PMCC : Upto 132kW

MCC/ASB : MOVs & other miscellaneous

motors/loads, if applicable

  1. Motor Starter Type

i. Contactor and switch fuse with overload relay : Up to 22 kW

ii. Contactor, switch fuse & overload relay with : 37KW and up to

55kW

CBCT for earth fault protection (CTUM + VAA relay)

iii. Contactor and switch fuse with numerical motor protection relay : above 55kW and up to 75KW

iv Air circuit breaker with motor protection : above 75kW

v Contactor and MCCB with overload relay : Not applicable

vi Contactor, MCCB & overload relay with CBCT : Not applicable

for earth fault protection

vii Star-Delta starter : Applicable for

Sump pump

Motors/Slop transfer pump motors if rating exceeds 22kW (as applicable)

    1. Motor Controls : Ammeter (for motors rated above 5.5kW) and Start/Stop

pushbuttons as part of local control station. All other requirements as per process package and operating philosophy as per P&ID

i Auto / Manual switch : Near motor/control room

ii. Local/remote switch : Near motor

iii. Normal / Standby switch : N.A

iv. Sequence interlock : PLC /Instrument panel/switchgear

v. Process interlock : PLC /Instrument panel/switchgear. Reacceleration equipment : PLC /relay panel/switchgear

vii. Control voltage for Contactor Starter : 240 V AC

viii. Control supply for contactor starter : tapped from Phase-Neutral

    1. Motors


Motors


High voltage


415 volts


Enclosure: Indoor

Outdoor


IP55

IP55


IP55

IP55


Insulation class


F

(Temp. Rise limited to B)


F

(Temp. Rise limited to B)


Terminal box


Phase segregated/Phase separated /Phase insulated


-


Anti-condensation heater


Yes


Yes above 22kW


Additional canopy (FRP)

(outdoor motors)


Yes


Yes


Design voltage / frequency variation


±10 % / ±3%


± 10 % / ±3%



    1. UPS System

A. Redundancy : 0/50%/100%

B. Type of redundancy : Parallel redundant

C. Back-up time : 30 minutes

D. Inverter bypass transformer : Servo Controlled/Static

E. Bypass transfer control : Auto / Manual

F. Battery type : Lead acid (Plante)

G. Battery execution : 2x50%

6.8 Telecom/Communication System (As per Telecom group)

A. Plant Communication System : Existing plant communication system. Necessary additional communication call stations shall be procured and hooked up by us.

B. Telephone System :

C. Telephone system and :

plant communication system

D. No. of intercom and :

external P&T lines

E. Battery type :

F. Battery backup time :

6.9 Fire Detection and Alarm System

A. Type : Conventional/Addressable

B. Name of buildings to be : Substations and Control Rooms

provided with Detectors

C. Battery type : VRLA

D. Battery backup time : 48hours(Normal) + 30 minutes

(Alarm)

E. Detection System : Break Glass/ Smoke and

Temperature Detector

    1. DC System

  1. Battery type

i) Switchgear Protection, : Lead acid / Ni Cd /

VRLA

Control& critical lighting

ii) Instrumentation System : Lead acid/ Ni Cd /

VRLA

iii) Diesel Engine Starting : Lead acid/ Ni Cd /

VRLA

B. Battery back up time

i) Switchgear Protection and : 2 hours

Control

ii) Critical lighting : 2 hours

iii) SCADA & telecom : 30 minutes

iv) Diesel Engine Starting : 10 starts (FW pumps) &

6 start (others)

v) DC motors : NA

    1. Cables

The power and control cables shall have the following minimum cross sectional areas:

a) Medium voltage power cable : 2.5 mm² (Copper)/35

mm² (Aluminium)

b) Control cables : 2.5 mm² (Copper)

c) Lighting : 2.5 mm² (Copper)

d) Communication system : 0.9 mm dia (Copper)

e) Fire alarm system : 1.5 mm² (Copper)

Note:

1) For lighting inside the building, minimum 1.5 mm² copper conductor, PVC Insulated wire shall be used in conduit system (for circuit and point wiring), with proper colour coding.

2) All power cables up to 16 mm2 shall be of copper conductor.

7 Cabling System

    1. Cable details


Design Criteria


High voltage


415 volts


Loads located beyond 1 km


Overhead line/cable


-


Loads located 200-1000 m


3 core cables


3½-core cable for feeders and 3 core for motors


Load located up to 200 m


Cable


Cable / Bus trunking


Loads beyond 1 kA rating


NA

Bus duct /1 core cable


Recommended limiting size of multi-core cable (mm²)


300


300


Short-circuit withstand time (seconds)


0.2 (Outgoing)/0.60 (Plant)/1.0 (Incomer)


N.A.


Insulation voltage grade


Earthed


Earthed


Type of cable insulation


XLPE


PVC


Fire survival (Resistant) cable

Fire pump

Plant communication



No

-



No

No


FRLS type cable (Rev.B)


YES


YES



    1. Cable laying philosophy

A. Operating area : Unpaved- Directly buried,

Paved- RCC Trenches

B. Offsite paved area : Above Ground cable tray on

sleeper/ Overhead rack/RCC

trench

C. Offsite unpaved area : Above Ground cable tray (on

sleeper/ Overhead rack)

/directly buried

D. Cables for all areas : Armoured / Unarmoured

E. Type of cable trays : Galvanized prefabricated /Site

fabricated and painted

F. Special requirements : Cables for fire water system

shall be taken through underground trench starting from main substation (In case applicable).

G. Road Crossings for : Hume Pipes

underground cables

H. Road Crossings for : NA

Above ground cables
  1   2

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