Research on the degradation process and failure mechanism of high voltage DC contactor in electrical endurance experiment

The longer electrical lifespan and higher reliability of high voltage DC (HVDC) contactors have always been the requirements of the power distribution system. This paper carries out an electrical endurance experiment of a typical HVDC contactor under resistive load. Firstly, the typical waveforms of the contact voltage and coil current during the operation process are tested and presented. Then, the degradation trends of featured parameters such as pick-up time, release time, arcing time and contact resistance are extracted and analyzed. It is determined that the pick-up time and release time are the sensitive featured parameters for characterizing the degradation process of the contactor. The relationship between release time and arcing time are investigated. Furthermore, based on the variation trends of the pick-up voltage and the release voltage, it is discovered that the degradation of the opposing force is the root cause for the decrease in pick-up time and the increase in release time. Finally, the possible degradation and failure mechanisms of HVDC contactors are analyzed.