Protection function of circuit breaker
The circuit breaker, also known as an air breaker, is mainly composed of a main contact, a reaction spring, a hook, a lever, an electromagnetic trip and an undervoltage trip device. Can appear in the circuit over current, overheating, undervoltage, play a protective role.
Over current protection
When the load has a serious short circuit, the circuit current is very large, the electromagnetic tripping coil produces a strong magnetic field, and attracts the armature through the iron core, the armature acts, drives the lever to move up, the two hook tripping, depends on the action of the counterforce spring, static and dynamic contact is disconnected, thus cutting off the circuit.
When the load runs with high current for a long time, the temperature of the heating element of the thermal protection device of the circuit breaker rises, and the metal sheet is heated and bent, thus cutting off the power supply.
Under voltage protection
When the system power supply voltage is too low, the current flowing through the undervoltage tripping coil in the circuit breaker is small, and the magnetic field generated by the coil is not enough to attract the armature, so as to disconnect the power supply and protect the electrical equipment.