Abstract
To improve GIS insulation specifications, it is important to recognize the insulation characteristics under oscillatory overvoltage waveforms occurring in the field. This paper describes investigations of insulation characteristics for single-frequency oscillatory waveforms with various conditions of gas pressure, gap length, surface roughness of electrode and bias voltage that is remained on electrode previously. As a result, it was obtained that minimum breakdown voltages (Vmin) were proportional to gas pressure (p) and gap length (d) in the range of experimental condition. Therefore Vmin were proportional to the product of gas pressure by gap length (pd). On the other hand, Vmin were independent on surface roughness of electrode and bias voltage in the range of experimental condition. Thus, it was verified that the experimental conditions, which had been treated in the series of research for the insulation characteristics under oscillatory waveforms, were appropriate to simulating the actual field conditions.
