Lightning Arrester
Lightning Arrester
Lightning Arrester
Working principle of LA
Ref Figure
The LA conducts at Impulse Spark over
Voltage and surge is diverted to the Earth.
The voltage across the LA remains at
Residual Value B for a short time.
Rating of LA
Arrestor ratings ( IS 3070/ 1974 Part1)
1) Voltage rating of LA
= Line to line voltage 1.1 coefficient of
earthing.
(Assuming coefficient of earthing equals 0.8
for effectively earthed system ie, ELG/ ELL)
Rating of LA
1) Distribution Class:
For lighter duty up to 34.5 kV.
2) Intermediate class:
For moderate duty up to 138 kV.
3) Station Class:
For heavy duty applications from 2.4 KV to
800 KV.
r
R
SiC Arrester
Zn O Arrester
VOLTAGE
Region 1
Leakage
region
Region 3
Region 2
High Current
Region
VOLTAGE
Non linear
conduction Region
High Current
Region
Discharge current
COV
MCOV
Normal operating voltage
Surge
current
10 KA
VOLTAGE
Non linear
conduction
Region
Discharge current
COV
MCOV
Normal operating voltage
High Current
Region
Arrester
rating
kV rms
MCOV
kVrms
COV
kV crest
11
33
30
26
38
66
60
51
83
132
120
102
184
220
198
168
290
400
360
306
490
420
245
145
1425
1050
650
390
198
120
MCOV
306
168
102
10
10
10
3 or 2
100
100
100
System BIL
kVp
kV
kA
mm
Weight
kg
Height
mm
420
245
145
10500
6125
3625
570
230
135
4265
2755
1560