Study of creeping discharge on hardwood timber under AC and DC voltages

This paper studies creeping discharge on hardwood timber under AC and DC positive and negative voltages. Experiments have been carried out on hardwood timber which is commonly used as supporting structure for overhead power distribution lines. Differences between AC, DC positive and DC negative discharges are investigated. Creeping discharges developed on the surface of the hardwood timber are recorded using highly sensitive and low light camera and the surface area of the discharges developed under different voltages are quantified by computing the surface area of the discharges. In addition, the breakdown time of hardwood timber is measured. Effects of increasing voltage, capacitive effects of creeping discharge have been studied. The results show that the breakdown time of hardwood timber in DC positive voltage is shorter than DC negative and AC voltages. Capacitive effects on the breakdown time are also studied in this paper. These results provide new insights into the role of creeping discharges leading to the breakdown of hardwood timber and the subsequent burning of the timber.