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Power cabinet 110 kW (3P). One of the IGBT transistors (400A) on the bus is broken.

I heard that it's necessary to change all three transistors. And that it's important that all three transistors should have absolutely identical characteristics.

Is that true? Or can I change only the broken transistors?

TonyM
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Sid
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    You should let someone who knows this do this. Sorry. You don't want to be the last person to have touched the system when switching of 400A to anything fails. – Marcus Müller Nov 01 '22 at 17:26
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    "cabinet" is a very generic term. A metal enclosure with things inside! You should ask whoever designed the stuff in the cabinet. Random people on the Internet will not be held responsible if you take their advice and 110kW blows up in your face and kills you. – user253751 Nov 01 '22 at 18:34
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    In general, replace all three. BUT, what caused one to fail initially? There is a high probability that replacing all of them will NOT solve the problem and instead also blow, costing yet more money. Suggest having an industrial repair service (whom clearly states they do repair that type of equipment) inspect it. – rdtsc Nov 01 '22 at 19:04
  • all 3 replace. Ok. But, once again... Is that true, that they all should be absolutely identical? – Sid Nov 01 '22 at 19:39

1 Answers1

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The reason why it's generally recommended to replace all three IGBTs in case one has failed is not that they have to be exactly matched (no two IGBTs that you buy, even in the same package, will be perfectly matched). Rather, when one IGBT has failed, the others most likely have been damaged as well due to the excessive currents flowing when an IGBT shorts out. They might not have failed completely yet, but they're almost certainly degraded.

Matching isn't particularly critical as long as all IGBTs are the same model and from the same manufacturer. It's critical that they're new and known undamaged.

Jonathan S.
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