Worst thing that can happen to a transformer?
Worst thing that can happen to a transformer?
(OP)
Inspired by thread238-378765: Out of phase switching on step up transformer and a real case in a 10 kV/400 V station, I ask what would the worst possible failure be? A case that makes primary current increase above any expected short-circuit current in the primary. So high, in effect, that the protection relay caught fire.
I know one case. And I have recordings of what happened on the LV side.
What are your worst cases? And what caused it?
I know one case. And I have recordings of what happened on the LV side.
What are your worst cases? And what caused it?
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.






RE: Worst thing that can happen to a transformer?
RE: Worst thing that can happen to a transformer?
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Worst thing that can happen to a transformer?
When the OCTC was moved to the next position what happened was not shorting of taps-if so it would have been a minor failure,most probably, the relays would have cleared it.In the case mentioned it was an opening of the circuit,just as in a circuit breaker, causing a massive arc and consequent failure mode.
RE: Worst thing that can happen to a transformer?
The relays didn't see the fault because of increase in line current was small due to the auto-transformer effect - this fault was akin to an inter-turn fault which are notoriously difficult to see using CTs at the terminals.
Interesting thoughts on source of the arcing. The conclusion at the time was that the switch broke up because of the forces due to fault current and that initiated the arc. There was heavy damage to the adjacent poles where the short occured, but your hypothesis is certainly plausible as a source of the ionised gas. Thank you for the idea - I don't know if that was considered at the time because I was on the team trying to get the station operational, while others were involved with the investigation.
Will see if I can find a photo or two.
RE: Worst thing that can happen to a transformer?
The worst one I heard of was a transformer that had an internal fault during energisation that caused the tank to split (not UK). The ensuing fire was like a flame thrower and killed a couple of guys leaving those next to them virtually uninjured. That's why I hide round the corner if I'm nearby when we energise a transformer.
RE: Worst thing that can happen to a transformer?
Well-known in the industry certainly.
One of the less emotion-laden sources on the internet is here: http://www.corporateaccountability.org.uk/Deaths/t... and there are links to the popular press if you want them.