Abstract
The breaker is one of most important electrical equipments in the power system,mainly in the infrequent operation of the distribution lines or as a power switch on the use of electrical power system. Protect electrical power system out of overload、short circuit and grounding fault.,to make sure the electrical power system reliability and security,the application is very extensive.with the rapid development of the power electronic and microelectronic technology,the smart breaker with the microprocessor becoming capability and flexible ,this unique performance characteristics cannot replaced by others. Th way the smart breaker's protection was already use electronic switch instead of traditional electromagnetic switch. Also something new function was included such as self-checking communication with computer and so on.