Real-time circuit breaker health diagnostics

Utilities have hundreds of circuit breakers that they plan to monitor for the purpose of accurately assessing health and performance. As circuit breakers age over time, improper operations can become more likely and cause problems on the power system. Utilities are making efforts to develop automated circuit breaker monitoring systems that diagnose the electrical and mechanical health of their circuit breakers in real time. This is a shift in the maintenance paradigm from time-based maintenance to as-needed maintenance. This shift comes with the benefit of maintaining adequate circuit breaker performance while reducing overall maintenance costs. This paper details a system developed at American Electric Power (AEP) for monitoring circuit breakers and presents an overview of the results of field trials that show the maintenance reductions gained by predicting required maintenance instead of scheduling it. The system collects data from deployed intelligent electronic devices (IEDs) to monitor circuit breaker conditions, including degrading performance, contact wear, SF6 gas integrity, gas pressure, compressor run times, compressor run currents, and much more. The system discussed in this paper also provides the ability to monitor real-time trip and close coil assembly performance by recording mechanical and electrical characteristics including trip coil current and operate time during circuit breaker operations. Recorded trip and close coil characteristics are used to diagnose armature misalignments, lubrication problems, interwinding short circuits, and so on to assist with maintenance and ensure future operations. Monitoring circuit breakers also allows for accurate price assessments of circuit breaker assets and aids in maintenance and replacement. Additionally, this paper presents an implemented monitoring solution that was used to demonstrate these capabilities and benefits.