The Design Of Online Monitoring Devices Of Intelligent Circuit Breaker Performance Parameters

As a crucial part of the power system, circuit breaker affects the security of the supply and distribution system greatly. Its performance quality directly affects the stability and reliability of the entire power system. Therefore, keeping the circuit breaker in good working condition is the key to avoid or reduce the loss caused by power grid accidents. According to the different using environment, predictive maintenance and planned maintenance are two main ways China using to maintain the circuit breaker.Conducting condition monitoring becomes a necessary mean to maintain predictive maintenance of circuit breakers. In this paper, a circuit breaker performance parameter on-line monitoring device is designed with the ARM microprocessor LPC2478as the hardware’s core part to control the whole device, with μC/OS-Ⅱ as the operating system, which uses C language programming basic functional program and with monitoring interface made by VB in host computer to analyze and process on-site collected data. The device is composed mainly of interface control panel, on-site acquisition&control unit and the host computer. The main parameters of the monitoring includes current and voltage signals of the circuit breaker while in open/close process, SF6gas pressure signal, the current open/closed state and the time of circuit breaker. On-site acquisition and control unit has three operating modes. Mode1is made for dealing with the current and voltage signals collected by the sensor; mode2is responsible for the collection and calculation the state and time of open/closed; mode3controls the opening and closing of the circuit breaker. The processed data will be transmitted to the host computer via the serial port, which can be presented both in waveform and data on host computer’s screen, besides, it also can be enlarged and stored. Then a period operating state of the circuit breaker will be predicted according to the final analysis of the changing signal waveform and data and finally given to the maintenance personnel.The paper firstly introduces the gas pressure gathering principles of SF6, measurements of time behavior of circuit breaker and analysis of closing coil’s current and voltage. Then the paper elaborates the design and realization of the on-site acquisition&control unit and introduces how to use VB to get the displaying, querying and storing function on host computer. Finally, the paper demonstrates and analyzes the debugging results of the entire system under laboratory condition.