Research on the Closing Erosion Characteristics of 12kV Air Load Switch Arc Contacts

During the closing operation of 12kV air load switches, there is a surge current. The arc erosion caused by the breakdown arc, as well as the mechanical wear between the dynamic and static arc contacts, can severely erode the arc contacts. In order to investigate the erosion characteristics of the load switch arc contacts during the closing process and to enhance the electrical life of the load switch contacts, this study involves conducting 500 closing erosion experiments on the CuW80 arc contacts of phases A, B, and C of the air load switch. Concurrently, 500 erosion control experiments are being conducted. Each closing experiment records the dynamic resistance, static contact resistance, peak current, and arcing time of the arc contacts. After every 100 closing experiments, surface photos of the contacts are taken, and the mass loss rate is measured and calculated. The paper ultimately analyzes and summarizes the erosion characteristics of the arc contacts of the air load switch during closure and discusses the erosion mechanism. It has been found that the mechanical wear of the arc contacts after they have softened due to arc erosion during the closing experiments is much greater than the erosion caused by the pre-arcing arc before closing. At a closing speed of 4.5 m/s, an arcing time of less than 6 ms, a peak current of 650 A, and a number of closing tests at 500 cycles, the mass loss rate during the mechanical wear process exceeds 1.6 mg/C, which is also the primary reason for the increased mass loss of the contacts under closing conditions.