BusBar High Heat Discoloration Help Needed

[Steve1978]

Hi, I am trying to see if I can gain a better understanding of what happened with this BusBar inside a 750kva UPS system. The vendor is claiming that they believe external debris got into system and caused a short and the system to essentially have to be rebuilt.

When I look at it it looks like the front compacitor bank that sits over the busbar may have had no oxygen touching the copper surface,meaning the compacitor bank was sitting ontop of busbar preventing discoloration (not suppose to happen). So im trying trying to decifer where the high heat was on busbar and why the discoloration occured on some sections.

Any help on interpretation of the heat is appreciated

https://files.engineering.com/getfi...22-8076-cc837357be0a&file=20220928_114643.jpg

 

[itsmoked]

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Power0020]

Looks like a short circuit carbon deposit for me.
any insulating material nearby?

 

[che12345]

Dear Mr. Steve1978 (Electrical)(OP)5 Oct 22 01:21
"... if I can gain a better understanding of what happened with this BusBar inside a 750kva UPS system. #1. The vendor is claiming that they believe external debris got into system and caused a short.... #2. .... it looks like the front compacitor bank that sits over the busbar may have had no oxygen touching the copper surface,meaning the compacitor bank was sitting ontop of busbar preventing discoloration (not suppose to happen)..... . to decifer where the high heat was on busbar and why the discoloration occured on some sections?

#0. It looks like a localized short-circuit. But, a) what caused the short-circuit and b) short to where? The whole bar is clean, therefore not over-loading.
#1. "... The vendor is claiming that they believe external debris got into system and caused a short ......" Was there any evidence of a) "debris" e.g. carcass of rodent/snake etc...? b) short to where...? Vender to substantiate his claim.
#2. "....it looks like the front compacitor bank that sits over the busbar may have had no oxygen touching the....". The clearance[ between the capacitor bank and the busbar is NOT shown/reported. b) A flash-over across the air between the earthed capacitor bank tank and the busbar may? occur when the clearance < voltage level.
Che Kuan Yau (Singapore)

 

[LionelHutz]

Looks like an arc flash to me. Happens all the time in power conversion equipment. It's impossible to determine what started the arc based on that picture.

The capacitors are usually very closely coupled to the DC bus in this equipment. They need to be.

Electricians drilling conduit holes do leave debris more often than they should.

 

[JWR01]

The blast marks look like where a capacitor or IGBT exploded. Pretty normal damage when that happens right on the DC rail and since everything is so close together it doesn't take much debris to set it off. Likely whatever caused it was vaporized if it was debris. Ask for a failure analysis if it's extremely important.