ECN Forum Forums General Topics of the Trade General Discussion Area How breaker works?

Hello
Can someone explain to me or give me a link to about breaker?
Thanks

I don't know of any links, so I'll give this a shot.

most breakers that you're likely to encounter are thermal-magnetic.

The thermal part has a bi-metallic strip. Since the 2 metals expand & contract at different rates, the strip will bend as it heats up. If it bends enough, it will engage a trip mechanism and turn off the current. This is for overloads.

The magnetic part consists of a small coil in series with the load. When enough current flows, the magnetic field is strong enough to acuate the trip mechanism. This part is for short circuits, ground faults or any other large current flow.

Tom

http://www.tpub.com/neets/book3/8i.htm
Mike
Look around in this site, think youll find more info than you want.

Square D has this about breakers: Overcurrent Protection
The 23 page adobe acrobat file is about 1.4mb.

[This message has been edited by Phil H (edited 06-17-2001).]