CIRCUIT BREAKER

Circuit breaker

Circuit breakers are mechanical devices designed to close or open contact ends,thus closing or opening an electrical circuit under normal or abnormal conditions.
Circuit breaker consists of fixed and moving contacts which are touching each other under normal conditions and whenever a fault occurs,the trip coil gets energised,the moving contacts are pulled by some mechanism and so the circuit breaker is opened and the circuit is broken and when ever this interruption occurs an arc is inevitably formed between the contacts which prolongs the current interruption process for a duration ranging from 10 to 100 or more ms.
The fluids used in the circuit breaker should posses the properties of
1.High dielectric strength
2.Non inflammability
3.High thermal stability
4.Chemical stability
5. Arc extinguishing ability
6.Commercial availability at moderate cost.

Automatic circuit breakers are usually employed for the protection of electric circuits,are equipped with a trip coil connected to a relay or other means,designed to open the breaker automatically under abnormal conditions.
Types of Circuit Breakers
1.Oil Circuit breaker
2.Low voltage air Circuit breaker
3.Air blast Circuit breaker
4.Vacuum Circuit breaker
5.Sulphur Hexafluoride Circuit breaker