1. Application scope: this circuit breaker is for cut off fault circuit.

2. Two types: high voltage circuit breaker and low voltage circuit breaker. The demarcation line is not so clear, and which beyond 3KV is usually called high voltage circuit breaker.

3. The function of circuit breaker is to protect power circuit and electric motor.

4. Circuit breaker is usually constituted by contact system, arc extinguishing system, operating mechanism, the release and the shell.

5. Low voltage circuit breaker is also called air switch, and used to connect or cut off the load circuit. It also could be used to control the electric motor which is not frequently start.