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Discussion Starter #21 (Edited)
Or....does it's OCPD react before any given component ignition temperature is reached?

What's scary is this notion seems to be an inherent malady from lowly resi wiring up to sub stations....:eek:

~CS~


:lol: I am only laughing because it seems to be that way. BOOM seems to be the language of "yup, something broke" :(




A turn to turn short would likely be detected by a transformer differential relay. Normally current in should equal current out (corrected for the turns ratio and slight losses) If excess current is circulating inside the transformer from the short the relay will trip. There is also a sudden pressure device which senses a sudden and rapid rise in the transformer pressure that could trip it as well.

All our oil filled transformers get their oil sampled on a regular basis and they can detect if things are beginning to go south in the transformer.
That what I would expect, but it looks like this type of protection was optional?

In terms of turn to turn fault this is like creating another transformer winding? The circulating currents heat the shorted section?
 

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AKA Luketrician
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Sorry phone post :laughing:

I mean if a line short circuited or the transformer had a turn to turn short doesn't something cutout (shut off) the power off to the transformer? Similar to the NEC is a secondary feed from a dry type transformer shorted a breaker would trip.

Sudden pressure relays would detect internal shorts/faults, and hopefully initiate the protective circuitry in enough time to remove the TX from service before a catastrophic event occurs.

Before then, you would hope that the Buchholz relay, and/or other gas detection relay would detect the acetylene gases of the internal arc before conditions within the Tx became serious enough that the sudden pressure relays actuated.

Even before all of that, TXs should be on a Serveron system or something equivalent, that is constantly monitoring the TX oil for signs of trouble.
 

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Discussion Starter #24
Sudden pressure relays would detect internal shorts/faults, and hopefully initiate the protective circuitry in enough time to remove the TX from service before a catastrophic event occurs.

Before then, you would hope that the Buchholz relay, and/or other gas detection relay would detect the acetylene gases of the internal arc before conditions within the Tx became serious enough that the sudden pressure relays actuated.

Even before all of that, TXs should be on a Serveron system or something equivalent, that is constantly monitoring the TX oil for signs of trouble.

And even then, I would think something is monitoring transformer differential current, over current with some type of transfer trip scheme in place. I have a feeling this substation had no protection.
 

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And even then, I would think something is monitoring transformer differential current, over current with some type of transfer trip scheme in place. I have a feeling this substation had no protection.
I think is is kind of like the AFCIs...there is a limit on how much protection you can provide without excessive nuisance trips. The utility is in the business of selling the power and they can't do that when the protective device opens the circuit:)
 

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Discussion Starter #26
I think is is kind of like the AFCIs...there is a limit on how much protection you can provide without excessive nuisance trips. The utility is in the business of selling the power and they can't do that when the protective device opens the circuit:)

:lol: :laughing::thumbup:
 

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Guys, I drove by today and snapped some pictures of the rebuilt substation. You can see precautions have been taken so this will never happened again.

 
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