The EMC And Reliability Design Of On-line Inner Vacuum Pressure Monitoring System For Vacuum Circuit Breaker

In power grid,circuit breaker is the core part of controlling power distribution and ensuring safe operation.Vacuum circuit breaker is widely used for its advantages of compact structure,high capacity breaking capacity,no pollution to the surrounding environment,long life and simple maintenance.Vacuum interrupter is the core component of vacuum circuit breaker,and its internal vacuum directly affects its breaking performance.When vacuum circuit breaker is running normally,the internal vacuum degree will gradually decrease as time goes on.When the vacuum circuit breaker is in a state of disconnection,the vacuum between the static and dynamic contacts is a high voltage insulation medium.If the pressure rises above 10-1Pa,it will be broken,fail to work and even damage to the equipment.With the popularization and popularization of vacuum circuit breaker in power grid,the detection and judgment of its running state become the key content of daily maintenance.In view of the shortcomings of the existing coupled capacitance method,such as unstable acquisition signal,large fluctuation range,narrow range of vacuum value acquisition,and so on,this paper eliminates the negative influence of external environment and signal itself by functional exploration,reliability design and EMC design.This paper first introduces the current research status of vacuum on-line inspection of vacuum circuit breaker,analyzes the area of electromagnetic compatibility in the detection equipment by and large,and explains the adverse effects of electromagnetic interference on the equipment in these areas.Then designs the overall design of the detection system in general.including principle introduction,parameter simulation,hardware design and software design.In this part,each cell of the design is analyzed in detail,and the design idea and principle are expounded.Considering the working environment of vacuum circuit breaker,reliability design and EMC design are fully considered in the design.Reliability design includes three aspects of electronic devices,electronic circuits and embedded systems,the first couple of which designed as a reference by the Mean Time Between Failure,It is calculated that the Mean Time Between Failure value of the whole circuit is 5.58×105h.The third aspect which named the design requirements of the software part of the embedded control circuit is evaluated by the response speed.The program is designed to collect and calculate and send a data to 0.33 s,because the change of the vacuum interrupter is a long process,the response speed of the embedded system is also in line with the requirements.Electromagnetic interference in the design of electromagnetic compatibility is fully analyzed.grounding,shielding,filtering and isolation are adopted to solve the problem of electromagnetic interference in the design of the probe,signal transmission and circuit design.According to the requirements of national standard GB/T 17626,we designed and manufactured an online vacuum measurement system that meets the requirements of reliability and electromagnetic compatibility.The electromagnetic compatibility and anti-interference ability of the device is verified in three aspects: ESD immunity,surge immunity and power frequency magnetic field immunity.Meanwhile,according to the requirements of national standard GB/T 2423,reliability tests were carried out at different time and weather.The test results meet the requirements of electromagnetic compatibility and reliability.