construction of MCB

lindsay2 · Posted: Thu Nov 22, 2007 4:17 pm Post Subject: construction of MCB

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

briwire · Posted: Sun Dec 02, 2007 12:52 am Post Subject:

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.

plugwash · Posted: Sun Dec 02, 2007 2:28 am Post Subject:

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.

jossper · Posted: Mon Dec 03, 2007 3:35 pm Post Subject:

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

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