construction of MCB

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lindsay2

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• 22 Nov 2007

• #1

can anyone tell me the construction of MCB - thermal operation?
thanks

 

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briwire

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• 2 Dec 2007

• #2

Most have a low resistance element in the current path that heats up depending on its rated current. This causes a deflection of a bi metallic strip which operates a mechanical trip to open the circuit.

I believe some like Merlin Gerin incorporate a magnetic function also.

 

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plugwash

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• 2 Dec 2007

• #3

afaict all MCBs to current british standards have both a thermal trip for long term minor overcurrents and a magenetic trip for fast reaction to short circuit. I don't know if other countries standards are the same.

 

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jossper

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• 3 Dec 2007

• #4

On page 35 of this PDF is a good cutaway pcture of an MCB with an explanation

http://www.electrium.co.uk/Wylex2007.pdf


Paul