Characterizing impedance profiles for leakage currents from HV insulators on wooden poles

Abstract

In this paper, the impedance characteristic profiles of wooden power poles altering the leakage current from high voltage (HV) insulators are investigated to better understand the role of wood in leakage current signatures. A comparison with past research shows the capacitive components of a pole's impedance have previously been ignored, however, has little effect on using an impedance value for effective resistance. Examining the impedance properties of typical Copper Chromium Arsenate (CCA) impregnated wood for 66 kV distribution poles shows dangerous conductance properties of wood at this voltage, providing an explanation for these poles catching fire at triple the rate of 22 kV distribution poles. After a systematic investigation of wood used for poles, a preliminary impedance characteristic of wooden poles in Victoria, Australia is established for the first time, where the pole is weathered, CCA impregnated and operating at 22 kV under both dry and wet weather conditions.