Research On The On-line Monitoring System For Mechanical Characteristics Of Vacuum Circuit Breaker

In electrical power system, circuit breakers undertake dual tasks of protection and control as the most important switchgears, so the reliability of the circuit breakers is very significant. With the increase of the voltage and capacity of the electrical power system, oil circuit breakers cannot meet the interrupting and safety performance requirement any more. On the other hand, with the development of technologies, vacuum circuit breakers have the ability to interrupt current with higher switching capacity. The working voltage of the vacuum circuit breakers becomes higher and the ability of arc extinction is enhanced. The vacuum circuit breakers become more reliable and vacuum circuit breakers have took the lead in the field of middle-voltage switchgears.To insure the reliability of the vacuum circuit breakers, monitoring the mechanical characteristics is needed. With the analysis of the monitored mechanical characteristics, the working state of the vacuum circuit breakers can be judged. Then proper measures will be adopted to make sure that the vacuum circuit breakers are working safety, and the goal of electrical power system to work reliably and economically can be achieved.Under this former circumstances, this project have developed a mechanical characteristics monitoring system of vacuum circuit breakers. It can work on-line for a long time and can communicate with upper computer which can display the curve of the mechanical characteristics.This project uses linear displacement sensor with high linearity to collect the signal of the displacement. TMS320F2812chip from TI company is employed as the central processing unit of this monitoring system. It receives the signals and processes them to calculate the opening time, closing time, overtravel, opening distance and average velocity of the vacuum circuit breakers. These parameters are displayed on the LCD12864to be looked up in the work field conveniently. At the same time, these parameters are transmitted to upper computers by RS-485and the mechanical characteristics are displayed.At last, the on-line monitoring system and mechanical characteristics tester are tested at the same time. Contrasting these two groups of data to make sure the on-line monitoring system is correct. The mechanical characteristics of the vacuum circuit breakers under different voltages of the discharging capacitor are also tested to judge the reliability of the on-line monitoring system.