Radiometric Monitoring Technique for High-Voltage Circuit Breakers

In this study, a new technique for circuit breaker diagnosis, based on broadband microstrip antennas, is presented. The diagnosis is based on the electromagnetic signals radiated by electric arcs in circuit breaker poles during opening operations. From each measured signal, several parameters are calculated, such as arc duration and signal energy, which are then processed by a statistical analysis routine, providing information that allows a correlation between the radiated signals and the degradation of the breaker contacts to be established. A current injection system was used in order to produce electric arcs. The technique was tested using nine contact samples, with different degradation levels. With the obtained results, it can be verified that the proposed technique is able to provide information regarding contact degradation level, arc duration, arc reignitions, and mechanical defects. The proposed technique is a simple and non-invasive solution, since the antenna can be placed far away from the equipment under evaluation. The use of antennas is a low-cost solution to circuit breaker monitoring, and since it provides a continuous monitoring system, a database containing the evolution history of contact degradation may be available.