Lightning Arrester Failure

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Mumbaigirl

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Location
USA
Occupation
Electrical Engineer
Please pardon my very limited knowledge about this.

We recently had a partial outage at the plant where we blew a lightning arrester inside a 13.2kV switch, blew the fuses off the 13.2kV interrupter switch upstream of that switch and then tripped the main breaker on the bus feeding the interrupting gear.

The utility mentiones they did not notice a surge or an over-voltage event. The medium voltage switch line up is extremely old and it might have been a few years since these arresteres were replaced. They seem to be porcelein arresters (picture of the damaged arrester attached).

1) We were able to remove the arresters, replace the blown fuses. We mgeered out the cable and the bus and were able to bring back the plant online. But I am worried about not having arresters in the switch. What risks am I looking at? Without the arrester, am I looking at damaging the 13.2kV-480V transformer downstream? Or should transfomer protection be able to protect it. Would like to understand risks for production downtime and probably outline it in an email so my manager is aware.
2) Where do I begin with troubleshooting what the root caue could be?

I will appreciate any help I get on this. Thank you in advance!

Image (5).jpg
 
Management should be notified to submit RFQ's for a lighting protection study.

If Zeus and Poseidon don't have a better place to unleash their wrath, then your electrical service will get it again.
 
Was it lightning that caused it?
Surge arrestors protect from a few different transients.
Could be an old arrestor that finally broke down. Looks like a station class arrestor.
 
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