Lightning Arrestors

[BIBleiler]

Could anyone give me some insight into the causes of a lightning arrestor failure on our plants high voltage (34kV) service. The rep from the local power company told me the line was reset 3 times, twice on auto-reclose and once manually. The arrestor appeared to have been blown to bits and ignited a fire in the brush. I believe the arrestor was of the air gap type. Needless to say, I would like to prevent this from happening in the future. Any suggestions towards this end are greatly appreciated.

 

[busbar]

If you are on the North American continent, IEEE Transactions on Power Delivery returns a dozen hits for “arrester failure” doing a search at ieeexplore.ieee.org If you are not an IEEE member, the papers {more recent in PDF} can be purchased outright.

 

[jstickley]

In addition to simply ensuring your arresters are properly sized, I would not use air-gap arresters in the future. My understanding is that weathering tends to allow contamination of the air-gap to occur over time, reducing the breakdown voltage of the gap and allowing the arrester to operate at lower voltage surge levels.

 

[rbulsara]

What leads you to beleive that LA in fact failed not 'operated' because of an acutal voltage surge?

What was the weather like in the area at that time?


Has this happened before?

What is the physical conditons at the site and at the LA? Dusty? Muggy? damp, wet? clean?..

Any possibiliy of resonance?

 

[RRaghunath]

The line was re-closed repeatedly, presumably, on a steady fault (not the transient variety). I guess the fault was phase - earth (most common in OHLs).

It is known that earth fault in one phase causes voltage in other phases to ground to raise up to a level of 1.732 times normal Ph-E voltage.

This higher voltage means increased stress on the LA and can lead to its failure, especially when it o happens in quick succession as in the subject incident. If the LA failed belongs to the healthy phase, the above explanation should be valid. You may like to verify.

The above tries to supplement the other good suggestions by others such as ageing of LA, actual lightning strike.

 

[cuky2000]

To mitigate the effect of blowing surge arresters in the future couple alternative could be implemented:

1- Improve the resistance of the SA lead cable:
a- Measure the actual resistance.
b- Add additional ground rod(s).
c- Replace/add ground conductor to reduce resistance.

2- Replace the damage air-gap surge arresters by metal oxide units. Made sure to elect Intermediate or station type with adequate energy release capability.

 

[light1]

Could you post the lightning arrester data?

 

[stevenal]

Polymer housed arresters can fail without fragmenting.

 

[busbar]

stevenal — Do you know if 'non-brisant' failure of polymer-housed devices is thought to originate from moisture ingress?

 

[peebee]

As mentioned by rraghunath: "It is known that earth fault in one phase causes voltage in other phases to ground to raise up to a level of 1.732 times normal Ph-E voltage."

On ungrounded systems, that number could rise to 6x or 7x due to capacitive charging.

 

[stevenal]

Busbar,

I'm sure moisture accounts for lots or most of failures regardless of the housing material. We see arrester failure as a problem, but porcelain shrapnel is a safety issue that can be avoided.

 

[busbar]

Agreed that ringing in one’s ears is desirable to airborne ceramic shards plus the ringing.