2012 Volume 132 Issue 3 Pages 268-275
Micro discharges (MDs) such as spark or partial discharges on distribution lines, which occur by degradation of insulators, insulated wires, bushings, etc., may cause television interference or ground fault. A technique for locating MDs using differences in arrival time of electromagnetic pulses radiated from the MDs has been investigated recently. However, the technique requires a large and expensive apparatus such as a digital storage oscilloscope able to record the received pulse signals very fast. We investigated a new technique to estimate the direction of arrival (DOA) of the electromagnetic pulses using analogue signal processing, and produced a prototype of a MD locator. In order to evaluate the estimation error of DOA, we performed several experiments to locate spark discharges about 50nC/pulse on testing distribution line by using the MD locator. The average estimation error was about 5 degree, and the error of azimuth was several times larger than that of elevation in most cases. This reason is considered that resolving power of azimuth became lower than that of elevation owing to configuration of receiving antennas. We also tried to locate MDs on real distribution lines, and confirmed that there was no significant influence of reflected or carrier waves on DOA estimation.