Development of Acoustic Diagnostics for Opening and Closing Operations of Gas Circuit Breakers

High-voltage gas circuit breakers (GCBs) are widely used in power systems in order to interrupt fault current. As more equipment ages, it is becoming increasingly important to diagnose and maintain their condition to preserve the reliability of power systems. Inexpensive, non-contact acoustic diagnostics have been developed for automating the maintenance and inspection of power systems. In this study, we developed a system for acquiring major signals such as the stroke curve, contact (touching point), and motor current along with acoustic data in order to estimate the opening and closing operations of GCBs under normal conditions. The features of the frequency spectrum, which correspond to the start and end instants of the stroke, were stored in advance. These instants were estimated by comparing the correlation coefficient between the stored feature spectrum and the measured one. The resulting estimations were within an error of about 2%, making the acoustic diagnostics suitable for monitoring GCB operation.