Development of diagnostic methods for vacuum leakage from vacuum interrupter by partial discharge detection

Investigation is made to establish a monitoring method for vacuum leakage from a vacuum interrupter (VI) using a discharge detection method. AC rated voltage is applied to a practical VI filled with air to cause partial discharge (PD) inside VI. A diagnostic method is studied using a number of sensors with different specification. An attempt is made to compare the detection sensitivity of PD for the various sensors. Experimental results reveal that the rise time and magnitude of PD signal waveform detected with each sensor vary depending on discharge phenomena occurring at different internal pressures of VI. As a result, it is suggested that PD detection with the suitable sensors can determine the internal pressure in VI, along with distinguishing PD signal from noise.