Discharge Properties in Low Vacuum and Vacuum Monitoring Method for Vacuum Circuit Breakers

One of the causes leading to the low performance of vacuum interrupters (VIs) is a slow leak. If no measures are taken, this phenomenon cannot be detected and the VI will develop serious faults. Therefore, an effective monitoring technique is essential. We experimentally investigated the discharge properties in the low vacuum region of a VI. We measured the signal intensity of the discharge signal caused by the discharge occurring inside a model VI whose degree of vacuum could be varied. Pulse pattern and pulse waveforms were also measured in various pressures. To understand the pattern generating mechanism, we simulated these discharge patterns. Two noise reduction method using timer and frequency filter was examined. Finally, we introduce on-line vacuum-monitoring device with an alarm to warn of the deterioration of the vacuum degree of VIs