Circuit Breaker Contact Diagnostics Based on Dynamic Resistance and Fuzzy Logic

This paper describes the application of the dynamic resistance measurement (DRM) for assessing the condition of power circuit breakers contacts. In the DRM tests, a resistance curve is generated, contemplating resistance values referring to the main and arcing contacts regions. The tests were performed with minimum oil circuit breakers (MOCB) of 800 A/15 kV/12.5 kA and 2.000 A/72,5 kV/31.5 kA, and a SF6 circuit breaker of 1.650 A/72,5 kV/25 kA. To perform the DRM tests, a system has been designed and developed, which employs a 4-channel digital oscilloscope, a stationary battery of 12 V/220 Ah, resistors to limit the current from battery , current and voltage sensors and a personal computer. The system is able to determine the dynamic resistance values since the beginning of the contact…