Diagnosis of Vacuum Degree in Vacuum Interrupter Based on Partial Discharge

Partial discharge characteristics in air under low vacuum region were studied to develop vacuum leakage detector system. The pressures were set at 1.3 Pa to 2.6 kPa in order to simulate the leakage of vacuum interrupter. The measurement of discharge occurring inside the vacuum interrupter was performed with current transformer, ICCD camera and photomultiplier tube. The detection of discharge light intensity with a photomultiplier tube was more sensitive compared with a current transformer. From this result, an attempt has been made to distinguish the pressure below and above 260 Pa on the basis of the rise time and peak intensity of discharge light pulses. Discharge pulse with longer rise time with larger pulse width were attributed to Townsend-like discharge at pressures below 260 Pa while that with the sharper rise time with smaller pulse width were characterized as streamer-like discharge above 260 Pa. In addition, the estimation of vacuum degree in vacuum interrupter was done based on phase-resolved discharge characteristics by utilizing artificial neural network