A circuit breaker refers to a switching 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 division of high and low voltage boundaries is relatively vague, and generally, those above 3kV are referred to as high-voltage electrical appliances.