Noninvasive condition assessment and event timing for power circuit breakers

Noninvasive diagnostics, involving short-time spectra, short-time energy, and automatic timing techniques, were used to assess the mechanical condition of oil and puffer circuit breakers and to determine the timing of events occurring during operation. Analysis of the vibration signatures leads to (1) the characterization of a circuit breaker through a single index, the resolution ratio, and (2) automatic timing algorithms. The accuracy of the automatic timing algorithms permits both the timing of events and the detection of shifts in the timing associated with changes in the condition of a unit. Application of these methods to several oil and SF₆ puffer circuit breakers is described. Results are reported for circuit breaker operation under unenergized and energized-loaded conditions