The Online Monitoring System of Vacuum Degree in High Voltage Vacuum Circuit Breakers Based on Electromagnetic Wave Method

This paper presents a method of online monitoring vacuum degree in vacuum interrupter of high voltage vacuum circuit breakers (HVVCBs) and corresponding signal processing circuit. The ring antenna is placed outside the vacuum interrupter to receive the electromagnetic signal generated by the pulse discharge. Then convert it into electrical signal and transmit to the signal processing system. The system filters the signal and amplifies it by a certain multiple at first. Record the number of processed pulse signals and the average amplitude of signals within 30s under different vacuum degrees. And then set a threshold value of amplitude and a threshold value of number. When the relevant parameters of the signal exceed the threshold values, the relay will be triggered to warn people of the decrease of vacuum degree. This method accomplishes vacuum discrimination without touching and changing the vacuum interrupter. And the system will raise an alarm when the vacuum pressure deteriorates, which is very important in application.