Explain the working principal of the circuit breaker?

 Circuit Breaker is one that makes or breaks the circuit. It has two contacts namely fixed contact & moving contact. Under normal conditions, the moving contact comes in contact with fixed contact thereby forming the closed contact for the flow of current. During abnormal & faulty conditions (when current exceeds the rated value) an arc is produced between the fixed & moving contacts & thereby forms the open circuit, Arc is extinguished by the Arc Quenching media like air, oil, vacuum, etc.