A New Measurement Method of the Dynamic Contact Resistance of HV Circuit Breakers

The proposed paper will present a new dynamic contact-resistance measurement method that has been validated by field tests which were performed on air-blast and SF₆ gas circuit breakers. The unique measurement method allows reproducible resistance curves to be obtained, which is not the case with the conventional method. Dynamic contact resistance curves obtained by using both the conventional technique and the new method are compared. By applying the novel measuring method, the dynamic contact resistance curve is easy to interpret. It is believed that the new measuring method can be used as a diagnostic tool for SF₆ gas circuit breakers whenever contact anomalies are suspected. This new measurement method allows for an accurate evaluation of both main- and arcing-contact conditions without dismantling the circuit breaker. Moreover, it provides the maintenance crew with relevant criteria for selecting the interrupting chambers that should be internally inspected