HV Surge arresters

[m3ntosan]

Does anyone have any experience in installing HV (400 and 132 kV) surge arresters upside down, hanging on a metal gantry 20m above the ground?
I’ve seen this type of arrangement due to lack of space around a transformer. Are there any (electrical) disadvantages that may arise from this?
I am assuming from civil viewpoint it’s not a good thing to hang heavy porcelain surge arrester.


May you grow up to be righteous, may you grow up to be true...

 

[stevenal]

Assuming your support is built for the weight, I don't see why weight would be an issue. Generally the sheds are shaped for the orientation, so you might want to order the arresters custom for this application. While you're at it, consider polymer over porcelain. Much lighter and easier to install. And when they fail, they won't take out bystanders and transformer bushings.

 

[dpc]

No electrical issues if proper clearances are maintained. You should verify with arrester supplier that they are suitable for inverted mounting.

David Castor

http://www.cvoes.com

 

[m3ntosan]

Are you sure that length and any 90 degrees angles of the link to the ground won’t affect the proper functioning?

May you grow up to be righteous, may you grow up to be true...

 

[stevenal]

Lead length always affects performance, and shorter is better. Measure it from the protected insulation, round trip. In this case it is the sum of the length from the transformer bushing to arrester plus the ground lead from arrester to transformer tank. I'm not aware of any issues with 90s.

 

[bacon4life]

We no longer mount arrestors upside down as a precaution.

We had a 115 kV arrestor mounted upside down that failed, although we could not conclusively identify the cause. The best guess at the time was that the attached bus work did not have enough thermal expansion joints which caused some deflection of the arrestor which combined with the upside down orientation to allow water ingress.

 

[dpc]

Sometimes they fail inexplicably even when mounted right side up.

David Castor

http://www.cvoes.com

 

[stevenal]

Excessive side loading in any orientation is a bad idea.

 

[racobb]

But if the design did not allow for thermal expansion of the bus, the arrestor would have probably still failed if upright at some point. Many units are mounted inverted and do not have problems if they are designed for it.

Alan

 

[bacon4life]

It very well could have been a random failure, but changing to more standard orientation was quite easy to do.

The side loading was not excessive, however it was cyclic which led to a theory that it had been flexed back and forth enough to allow water ingress.

Glad to hear others have had good experiences with upside down mounting.