electrical design basis

8/12/2019 Electrical Design Basis

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DESIGN BASIS FOR ELECTRICAL ITEMS

S.No. Description 110kV Chayadevi S/S

1.0 GENERAL

1.1 Standards : Relevant IS / IEC / IEEE / CBIP

standards & manuals

1.2 Service : Outdoor

1.3 System Voltage (kV rms) : 110

1.4 Highest system voltage (kV rms) : 123

1.5 Power frequency withstand capability (kV rms) : 230

1.6 Basic insulation level (kV peak) : 550

1.7 Creepage distance for insulators (mm/kV) : 25

2.0 MINIMUM CLEARANCES

2.1 Between Phase and earth (mm) : 1100

2.2 Between phases (mm) : 1100

2.3 Sectional clearance (mm) : 4000

2.4 Ground clearance (mm) : 4600

3.0 FAULT LEVEL PARAMETERS

3.1 Magnitude of Three Line fault current in kA : 31.5

3.2 Duration of fault current (Sec.) : 3

4.0 BUS BAR ARRANGEMENTS

4.1 Type of Bus : 2.5" IPS AL Tube (As per schedule

40)

4.2 ACSR Conductor : Lynx

5.0 EARTHING SYSTEM

5.1 Type : Solidly earthed system

5.2 Magnitude of earth fault current to be considered for earth

mat sizing (kA)

: 31.5 kA

5.3 Time duration for calculation of step & touch potentials

(Sec.)

: 0.5

5.4 Fault time duration for sizing the earthing conductor (Sec.) : 1

5.5 Type of joint for earth mats : Welded joints

5.6 Depth of buried conductor (mm) : 600

5.7 Average soil resistivity (Ohm-m) : Refer soil resistivity report

5.8 Area to be covered for laying earthmat : Complete fenced area.However

fence shall be isolated from main

earthing mate

5.9 Type of conductor & size : 75 X 8 GI

5.10 Material for treated earth electrodes : 3M long, 40 mm dia, GI Pipe

electrode with treated for

transformer neutral and Lightning

5.11 Material for un-treated earth electrodes : 3M long, 40 mm dia, MS Rod

electrode for others.


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6.1 System type : Lightning masts

6.2 Angle of coverage : As per Razevig method

6.3 Earthing down conductors for Lightning Arrestors and

Lightning Protection

: 25 x 3 GI flats

7.0 GENERAL

7.1 Details of relays and meters : -

7.2 Colour & finish of panels : -

7.3 Height of all panels with base channels : -

7.4 Control cabling philosophy : As in cable philosophy diagram

8.0 AVAILABLE AUXILIARY SUPPLIES

8.1 DC supply (V) : 110 V, -15% to +10%

8.2 AC supply (V) : 230 / 415 +/- 10% at 50 Hz +/- 5%

9.0 CIRCUIT BREAKER

9.1 Voltage : 123 kV

9.2 One Minute Power Frequency Voltage : 230 kV (rms)

9.3 Lightning Impulse withstand voltage : 550 kVP

9.4 Normal current : 1250 A

9.5 SC breaking current : 31.5 kA

9.6 Short time withstand current and duration : 31.5 kA for 3 secs

9.7 Operating sequence : O-0.3S-CO-3 min-CO

9.8 Operating Mechanism : Standalone spring charged.

9.9 Closing and opening device supply voltage : 110 V DC

9.10 Motor supply voltage : 230 V AC

9.11 Auxiliary supply voltage : 230 V AC

9.12 Frequency : 50 Hz

10.0 ISOLATOR :

10.1 Voltage : 110 kV

10.2 Maximum operating voltage : 123 kV

10.3 Power frequency with stand voltage : 230 kV



10.6 Short time current rating : 31.5 kA for 3 secs

10.7 Operating voltage of main switch motor : 230 V AC

10.8 Switch type : Double break center rotating type

10.9 Creepage distance of insulator : 25 mm/kV


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10.0 Pole to Pole distance : 2.7 metre

10.11 Mechanical interlock : To be provided between main switch

and earth switch and respective CB

11.0 CURRENT TRANSFORMER :

11.1 Normal operating voltage : 110 kV

11.2 Highest system voltage : 123 kV

11.3 Basic insulation level : 550 kVP

11.4 Power frequency high voltage : 230 kV

11.5 Short time current rating & duration : 31.5 kA for 3 secs

11.6 Normal current : 175A for both line CTs and trafo

side CTs

11.7 Operating frequency : 50 Hz

11.8 CT ratio, No. of cores & accuracy classes : Refer single line diagram

12.0 POTENTIAL TRANSFORMER





12.5 Voltage factor : 1.2 continuous & 1.5 for 30 sec


12.7 PT Ratio, No. of Cores & accuracy classes for 132kV

side

: Refer single line diagram

13.0 LIGHTNING ARRESTOR :

13.1 Rated voltage 96 kV

13.2 Nominal discharge current : 10 kA, heavy duty


13.4 Discharge current class : 3

14.0 Control and relay panel :

14.1 Auxiliary supply for instruments & relays : -

14.2 Auxiliary supply for space heaters and illumination : -

14.3 Metering, relays & other devices : -

14.4 Type of construction : -

14.5 Painting : -

15.0 Power and control cables

15.1 Power cable

15.1.1 Voltage grade : 1100V

15.1.2 Conductor : Aluminium strands

15.1.3 Insulation : PVC

15.1.4 Innersheath material : Extruded PVC


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15.1.5 Armouring : a) Galvanized round MS wire / strips

for multi core cables

15.1.6 Outer Sheath of insulation : PVC

15.2 Control cable

15.2.1 Voltage grade : 1100V

15.2.2 Conductor : Copper strands.

15.2.3 Insulation : PVC

15.2.4 Innersheath material : Extruded PVC

15.2.5 Armouring : Galvanized round MS wire / strips

for multi core cables

15.2.6 Outer Sheath of insulation : PVC

16.0 Bay marshalling kiosk

16.1 Construction : Sheet steel enclosure with minimum

thickness of 2 mm.

16.2 Mounting arrangement : Free standing type

16.3 Enclosure protection : IP-65 with canopy arrangement

16.4 AC distribution : all be planned for switchyard equipme

16.5 Paint shade : Bhoruka to indicate

17.0 Insulators, Hardwares and Connectors

17.1 Post Insulator

17.1.1 Type : Solid Core

17.1.2 Nominal Voltage : 110 kV

17.1.3 Highest System Voltage : 123 kV

17.1.4 Creepage Distance : 25 mm/kV

17.1.5 Cantilever Strength : 800 kg for Bus Support

600 kg for Isolator

17.1.6 One (1) minute power frequency voltage : 230 kV

17.1.7 Impulse Voltage : 550 kVP

17.2 Clamps and Connectors

17.2.1 Sizes : Suitable for 2.5" IPS and Lynx ACSR

Conductor

17.2.2 Material : Aluminium

17.2.3 Finishes : Smooth Polished and Corona free


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110kV KPTCL S/S

Relevant IS / IEC / IEEE / CBIP standards

& manuals

Outdoor

110

123

230

550

25

1100

1100

4000

4600

31.5

3

2.5" IPS AL Tube (As per schedule 40)

Lynx

Solidly earthed system

31.5 kA

0.5

1

Welded joints

600

Refer soil resistivity report

Complete fenced area.However fence shall

be isolated from main earthing mate

75 X 8 GI

3M long, 40 mm dia, GI Pipe electrode with

treated for transformer neutral and

Lightning arrestor

3M long, 40 mm dia, MS Rod electrode for

others.


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110kV KPTCL S/S

Lightning masts

As per Razevig method

25 x 3 GI flats

As in the SLDs

Bhoruka to indicate

Bhoruka to indicate

As in cable philosophy diagram

220 V, -15% to +10%

230 / 415 +/- 10% at 50 Hz +/- 5%

123 kV

230 kV (rms)

550 kVP

1250 A

31.5 kA

31.5 kA for 3 secs

O-0.3S-CO-3 min-CO

Standalone spring charged.

220 V DC

230 V AC

230 V AC

50 Hz

110 kV

123 kV

230 kV

550 kVP

1250 A

31.5 kA for 3 secs

NA

Double break center rotating type

25 mm/kV


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110kV KPTCL S/S

2 metre

To be provided between main switch and

earth switch and respective CB

110 kV

123 kV

550 kVP

230 kV

31.5 kA for 3 secs

400A for both line CTs and trafo side CTs

50 Hz

Refer single line diagram

110 kV

123 kV

550 kVP

230 kV

1.2 continuous & 1.5 for 30 sec

50 Hz

Refer single line diagram

96 kV

10 kA, heavy duty

50 Hz

3

220 V DC

230 V AC

As per SLD

Simplex Type

Bhoruka to indicate

1100V

Aluminium strands

PVC

Extruded PVC


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110kV KPTCL S/S

a) Galvanized round MS wire / strips for

multi core cables

PVC

1100V

Copper strands.

PVC

Extruded PVC

Galvanized round MS wire / strips for multi

core cables

PVC

Sheet steel enclosure with minimum

thickness of 2 mm.

Free standing type

IP-65 with canopy arrangement

Shall be planned for switchyard equipment.

Bhoruka to indicate

-

-

-

-

-

-

-

Suitable for 2.5" IPS and Lynx ACSR

Conductor

Aluminium

Smooth Polished and Corona free


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DESIGN BASIS FOR ELECTRICAL ITEMS

S.No. Description 11kV borad

1.0 GENERAL

1.1 Standards : Relevant IS / IEC / IEEE / CBIPstandards & manuals

1.2 Service : Outdoor

1.3 System Voltage (kV rms) : 11

1.4 Highest system voltage (kV rms) : 28

1.5 Power frequency withstand capability (kV rms) : 28

1.6 Basic insulation level (kV peak) : 70

1.7 Creepage distance for insulators (mm/kV) : 25

2.0 FAULT LEVEL PARAMETERS

3.1 Magnitude of Three Line fault current in kA : 40

3.2 Duration of fault current (Sec.) : 3

3.0 BUS BAR ARRANGEMENTS

3.1 Type of Bus : Aluminium busbar rated for 2500 A

4.0 EARTHING SYSTEM

4.1 Type : Non-effectively earthed

4.2 Magnitude of earth fault current to be considered for earth

mat sizing (kA)

: 40 kA

4.3 Fault time duration for sizing the earthing conductor

(Sec.)

: 3

5.0 AVAILABLE AUXILIARY SUPPLIES

5.1 DC supply (V) : 110 V, -15% to +10%

5.2 AC supply (V) : 230 / 415 +/- 10% at 50 Hz +/- 5%

6.0 CIRCUIT BREAKER

6.1 Type : SF6/ VCB

6.2 Voltage : 12 kV

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6.3 One Minute Power Frequency Voltage : 28 kV (rms)



6.6 SC breaking current : 40 kA

6.7 Short time withstand current and duration : 40 kA for 3 secs

6.8 Operating sequence : O-0.3S-CO-3 min-CO

6.9 Operating Mechanism : Standalone spring charged.

6.10 Closing and opening device supply voltage : 110 V DC

6.11 Motor supply voltage : 240 V AC

6.12 Auxiliary supply voltage : 240 V AC


7.0 LOAD BREAK SWITCH :

7.1 Voltage : 11 kV

7.2 Maximum operating voltage : 12 kV

7.3 Power frequency with stand voltage : 28 kV



7.6 Short time current rating : 40 kA for 3 secs

7.7 Operating mechanism : Manual

8.0 CURRENT TRANSFORMER :




8.4 Power frequency high voltage : 7028

8.5 Short time current rating & duration : 40 kA for 1 sec

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8.6 Normal current : 1800A for trafo CTs and 40 A for

UAT CTs


8.8 CT ratio, No. of cores & accuracy classes for 132kV

side


9.0 POTENTIAL TRANSFORMER





9.5 Voltage factor : 1.2 continuous & 1.5 for 30 sec


9.7 PT Ratio, No. of Cores & accuracy classes for 132kV

side


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