Intelligent circuit breaker is an important equipment in power supply and distribution system. It takes on the task of disconnection, control and regulation. With the continuous expansion of the scale and level of the power system, the network structure and operation mode of the system are becoming increasingly complex, and the traditional circuit breakers have become increasingly difficult to meet the requirements of the reliability, accuracy and real-time of the system. The rapid development of microprocessor, microelectronic sensing technology, control technology, communication and power electronics technology makes it possible to develop intelligent circuit breakers and become the development aspect of circuit breaker technology< br>? & nbsp; The intelligent circuit breaker is composed of power electronic technology and digital control device to form an execution unit, which replaces the auxiliary switch and auxiliary relay of conventional mechanical structure. The tripping and closing angle can be controlled according to the voltage waveform, the time of tripping and closing process can be accurately controlled, and the instantaneous over-voltage amplitude can be reduced< Br>Various information required for circuit breaker operation is directly processed by the digital control device installed in the circuit breaker equipment, so that the circuit breaker device can independently perform its local functions without relying on the substation level control system< br>? & nbsp; The new sensor is combined with the digital control device to independently collect operation data, which can detect equipment defects and faults, and send alarm signals before the defects become faults, so as to take measures to avoid accidents. The intelligent circuit breaker has a digital interface, which can send and receive GOOSE messages to achieve switch control< br>