Characterization of Composite Insulator Response Under HVDC - Insulator Impedance and Time Ratio

Nowadays, composite insulators are widely used in high voltage lines and for electric traction systems. The present paper aims to study the behavior of composite insulators under high voltage direct current. An experimental setup has been used to study the applied voltage and leakage current wave-forms in the presence of partial discharge, and the obtained waveforms are presented and discussed. The ratio between voltage and leakage current values illustrates the dynamic behavior of composite insulator with voltage variation. To illustrate that the dynamic behavior is not limited to magnitude, an insulator time ratio is proposed consists in dividing current peak time to the voltage one. This ratio illustrates the capacitive behavior of composite insulators under overvoltages.