Lightening Arrestor IR value
Lightening Arrestor IR value
(OP)
Dear all
Could you anybody tell the reasons for low Insulation resistance of 220kv/400kv Lightening Arrestor?
In our substation we got the following values
Test Voltage: 5000v dc
Meggar make Insulation Resistance instrument
Top stack : 7.5 Mega ohms
Bottom stack : 175000 Mega ohms
Total stack: 200000 Mega Ohms
LA is in service in 220kv Main Bus-II. However during Preventive Maintenance checks we identified above values recently.
As LA is completely sealed. The what are the factors effect this Low Insulation resitance values.
Regards
Could you anybody tell the reasons for low Insulation resistance of 220kv/400kv Lightening Arrestor?
In our substation we got the following values
Test Voltage: 5000v dc
Meggar make Insulation Resistance instrument
Top stack : 7.5 Mega ohms
Bottom stack : 175000 Mega ohms
Total stack: 200000 Mega Ohms
LA is in service in 220kv Main Bus-II. However during Preventive Maintenance checks we identified above values recently.
As LA is completely sealed. The what are the factors effect this Low Insulation resitance values.
Regards






RE: Lightening Arrestor IR value
The most common failure mode for arresters is moisture. The comparative test on a good arrester would help determine this. I've observed seals in which a gasket was improperly installed that allowed moisture to enter the arrester housing. Unfortunately, from a forensics standpoint, you usually have to chisel off the sealing area (assuming it's a porcelain housing) to find this.