Circuit breaker  refers to a switch device that can close, carry and break the current under normal circuit conditions and can close, carry and break the current under abnormal circuit conditions within a specified time. Circuit breakers are divided into high-voltage circuit breakers and low-voltage circuit breakers according to their scope of use. The boundary between high and low voltage is relatively vague. Generally, those above 3kV are called high-voltage electrical appliances.

Circuit breakers can be used to distribute electric energy, start asynchronous motors infrequently, and protect power lines and motors. When they are seriously overloaded or short-circuited or undervoltage, they can automatically cut off the circuit. Their function is equivalent to the combination of fuse switches and overheating relays. Moreover, there is generally no need to change parts after breaking the fault current. At present, they have been widely used.

Power distribution is an extremely important link in the generation, transmission and use of electricity. The power distribution system includes transformers and various high and low voltage electrical equipment, and low voltage circuit breakers are a widely used electrical appliance.

A circuit breaker is generally composed of a contact system, an arc extinguishing system, an operating mechanism, a release, a casing, etc.

When short-circuited, the magnetic field generated by the large current (generally 10 to 12 times) overcomes the reaction spring, the release pulls the operating mechanism to operate, and the switch trips instantly. When overloaded, the current becomes larger, the heat increases, and the bimetallic strip deforms to a certain extent to drive the mechanism to operate (the larger the current, the shorter the operating time).

There are electronic types that use mutual inductors to collect the current of each phase and compare it with the set value. When the current is abnormal, the microprocessor sends a signal to make the electronic release drive the operating mechanism to operate.


Post time: Jul-08-2024