Study of Leakage Current Behaviour on Artificially Polluted Surface of Ceramic Insulator

This paper presents the results of the study concerning to the leakage current behaviour on artificially polluted ceramic insulator surface. From the present study it was observed that there is a reasonably well-defined inception of current i.e. scintillations at a finite voltage.The corresponding voltages for extinction of the current are in the range of 0.8 kV to 2.1 kV.Obviously, the dry band formed in the immediate vicinity of the pin prevents smooth current flow as the voltage rises from zero. Only when the voltage is adequate it causes a flashover of the dry band and current starts flowing. As is common in similar current extinction phenomena, here also, the extinction voltages are significantly lower than the inception voltages. Further, the voltage-current curves invariably show hysteresis the leakage currents are lower in the reducing portion of the voltage. This is obviously due to drying of the wet pollutant layer thereby increasing its resistance. It is believed that this is the first time that such a direct quantitative evidence of drying in individual half cycles is experimentally visualized.

Study of Leakage Current Behaviour on Artificially Polluted Surface of Ceramic Insulator

This paper presents the results of the study concerning to the leakage current behaviour on artificially polluted ceramic insulator surface. From the present study it was observed that there is a reasonably well-defined inception of current i.e. scintillations at a finite voltage. The corresponding voltages for extinction of the current are in the range of 0.8 kV to 2.1 kV. Obviously, the dry band formed in the immediate vicinity of the pin prevents smooth current flow as the voltage rises from zero. Only when the voltage is adequate it causes a flashover of the dry band and current starts flowing. As is common in similar current extinction phenomena, here also, the extinction voltages are significantly lower than the inception voltages.Further, the voltage-current curves invariably show hysteresis - the leakage currents are lower in the reducing portion of the voltage. This is obviously due to drying of the wet pollutant layer thereby increasing its resistance. It is believed that this is the first time that such a direct quantitative evidence of drying in individual half cycles is experimentally visualized.