Influence of the injected current on dynamic contact resistance measurements of HV circuit breakers

Dynamic contact resistance measurement (DRM) is an effective technique for assessing the condition of power circuit breaker main contacts and arcing contacts. However, DRMs are easily affected by measurement condition, and they vary widely with changes of measurement condition, which is likely to lead to misjudgments. The problem can be relieved by increasing the injected current value. The proposed paper researched the influence of the dc injected current on dynamic contact resistance, and discovered that the average main contact resistance, the average arcing contact resistance, and the standard deviation of DRM curve decreased with the increase in the current value. At the same time, the reproducibility of parameters above improved. Besides, this paper also proposes a proper DRM strategy for the tested breaker.