INFLUENCE OF VERY FAST TRANSIENT OVERVOLTAGE WAVEFORM PARAMETERS ON THE BREAKDOWN VOLTAGE IN SF6 GAS GAPS

Gas insulation switchgear (GIS) has been widely used in electrical power systems for decades due to its good compactness and tightness, slight impact on the environment, and long maintenance cycle. However, it has been noticed that the failures of GIS insulation due to very fast transient overvoltages (VFTOs) increases with the increase of voltage levels. In this paper, a generating system of VFTO with different oscillating coefficients and double-exponential impulses with different front times was established. Using the system, the discharge characteristics of SF6 gas gaps under VFTO with different front times simulated by double-exponential impulses and different oscillating coefficients were studied. Experimental results show that the 50% breakdown voltage under different impulses…