Partial Discharge and Flashover Characteristics of Millimeter Metal Particles on the Insulator Surface in a GIS

Insulator flashover in field is a serious threat to the security and reliability of the gas insulated switchgear (GIS), and the metal particles on the surface of GIS insulator are considered to be a main cause of insulation fault. In previous studies, centimeter metal particles are usually examined in a GIS, which is obviously different from the actual field situation. In this study, a GIS insulator experimental platform is established, and the partial discharge (PD) and flashover characteristics of millimeter metal particles on the insulator surface in a 252 kV GIS are studied. The results indicate that under the operating voltage and routine PD test voltage, the discharges of millimeter metal particles are weak and sporadic: the discharge repetition rate is smaller than 60 times/s and the maximum apparent charge is smaller than 3 pC. As the voltage increases, the apparent charge and discharge repetition rate both increase slightly. The discharge is significantly enhanced only within a short time before flashover. This study provides an important reference for understanding the PD and flashover characteristic of millimeter metal particles on insulator surface, and is beneficial for improving the effectiveness of defect detection.