power circuit breakers

A circuit breaker is an automatically-operated electrical switch which is designed to protect an electrical circuit from damage caused by overload or short circuit. Unlike a fuse which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices which protect an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city. Circuit Breakers.

Operation

Some circuit breakers are implemented using a solenoid (electromagnet) whose pulling force increases as the current increases. The circuit breaker's contacts are held closed by a latch and, as the current in the solenoid increases, the solenoid's pull releases the latch which then allows the contacts to open by spring action. Another method of sensing current is with a bimetallic strip, which heats and bends with increased current, and is similarly arranged to release the latch. Some circuit breakers incorporate both techniques, with the electromagnet responding to short, large surges in current (short circuits) and the bimetallic strip responding to less extreme but longer-term overcurrent conditions. Remanufacturers and supplies new, used, obsolete and hard to find circuit breakers, switchgear and related parts in the 600V - 15KV class.