Minimum Clearance in HV

8/10/2019 Minimum Clearance in HV

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Minimum Clearance in Substation:

Voltag

e

Highe

st

Voltag

e

Lighting

Impulse

Level

(Kvp)

Switchin

g

Impulse

Level

(Kvp)

Minimum Clearance Safety

Clearance(

Mt)

Ground

Clearance(

Mt)Phase

-Earth

Phase-

Phase

11KV 12KV 70 0.178 0.229 2.600 3.700

33KV 36KV 170 0.320 0.320 2.800 3.700

132KV 145KV 550 1.100 1.100 3.700 4.600

650 1.100 1.100 2.700 4.600

220KV 245KV 950 1.900 1.900 4.300 5.500

1050 1.900 1.900 4.300 5.500

400KV 420KV 1425 1050(P-

E)

3.400 4.200 6.400 8.000

Electrical Clearance in Substation:Voltage Height of I

Bay From

Ground

(Mt)

Height

of II

Bay

From

Ground

(Mt)

Bay Width

(Mt)

Phase-

Phase

(Mt)

BetweenEquipm

ent

Earth

Wire

From

Ground

132KV

(Single)

8.0 - 11.0 3.0 3.0 10.5

220KV

(Single)

12.5 - 18 4.5 4.5 15.5

220KV

(Double)

18.5 25 25 4.5 4.5 28.5

400KV 15.6 22 22.0 7.0 >6.0 30.0

Standard Bay Widths in Meters:

Voltage Bay Width (Meter)

11KV 4.7 Meter

33KV 4.7 Meter

66KV 7.6 Meter

132KV 12.2 Meter

220KV 17 Meter

400KV 27 Meter

Standard Bus and Equipment Elevation

Voltage Equipment live Terminal

Elevation (Meter)

Main Bus Take of

Elevation

(Meter)Low High

11 KV/33KV 2.8To 4 5.5 To6.5 9 6.5To8.5

66KV 2.8To 4 6To8 9To 10.5 9.5

132KV 3.7To5 8To9.5 13.5To14.5 12To12.5

220KV 4.9To5.5 9To13 18.5 15To18.5400KV 8.0 15.5 - 23


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Phase spacing for strung Bus:

Voltage Clearance

11KV 1300 mm

33KV 1300 mm

66KV 2200 mm

132KV 3000 mm

220KV 4500 mm

400KV 7000 mm

Minimum Clearance of Live Parts from Ground:

Voltage Minimum Clearance to Ground (Mt) Section Clearance (Mt)

11KV 3.700 2.600

33KV 3.700 2.800

66KV 4.600 3.000

132KV 4.600 3.500

220KV 5.500 4.300400KV 8.000 7.000

Insulator String:

Voltage No of Suspension

String

Length (mm) No of Disc for Tension

String

Length i

66KV 5 965 6 1070

132KV 9 1255 10 1820

220KV 14 1915 15 2915

400KV 23 3850 2 X 23 5450

Nominal Span:

Minimum Ground Clearance:

Voltage Ground (Meter)

66KV 5.5

132KV 6.1220KV 7.0

400KV 8.0

800KV 12.4

Voltage Normal Span (Meter)

66KV 240-250-275

132KV 315-325-335

220KV 315-325-335

400KV 315-325-335

Voltage Tower

Type

Vertical Space

(Mt)

Horizontal

Space(Mt)

Total Height From

Ground(Mt)

66KV A 1.03 4.0 15.91

B 1.03 4.27 15.42

C 1.22 4.88 16.24

132KV A 7.140 2.17 23.14

B 4.2 6.29 22.06


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Indoor Substation Minimum Clearances

Distance Descriptions

0.9 Meter Horizontally between any item of equipment and thesubstation wall

0.6 Meter Horizontally between any Two items of equipment

1.2 Meter Horizontally in front of any HV switchgear

Clearance of Conductor on Tower

NORMS OF PROTECTION FOR EHV CLASS POWER TRANSFORMERS

The bottom most portion of any insulator or bushing in service should be at a

minimum height of 2500 mm above ground level.Location of L.A (From T.C Bushing):

Voltage BIL KV Peak Distance (Mt)

11KV 75 12

33KV 200 15

66KV 325 24

132KV 550 35

220KV 900 To 1050 Close To T.C

C 4.2 7.15 22.68

D 4.2 8.8 24.06

220KV A 5.2 8.5 28.55

B 5.25 10.5 29.08

C 6.7 12.6 31.68D

Voltage ratio & capacity HV Side LV Side Common relays

132/33/11KV up to 8MVA

3 O/L relays + 1 E/Lrelay

2 O/L relays + 1 E/Lrelay

Buchholz, OLTCBuchholz, OT, WT

132/33/11KV above 8

MVA and below 31.5

MVA

3 O/L relays + 1 dir.

E/L relay

3 O/L relays + 1 E/L

relay

Differential,

Buchholz, OLTC

Buchholz, OT, WT

132/33KV, 31.5 MVA &

above


E/L relay

3 O/L relays + 1 E/L

relay

Differential, Over

flux,Buchholz, OLTC

PRV, OT, WT

220/33 KV, 31.5MVA &

50MVA 220/132KV, 100

MVA


E/L relay


relay

Differential, Over

flux,Buchholz, OLTC

PRV, OT, WT400/220KV 315MVA 3 directional O/L

relays (with dir. High

set) +1 directional

E/L relays. Restricted

E/F relay + 3

Directional O/L

relays for action

3 directional O/L

relays (with dir. High

set)+1 directional

E/L relays. Restricted

E/F relay

Differential, Over

flux,Buchholz, OLTC

PRV, OT, WT and

overload (alarm)

relay

Minimum Clearance in HV

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