광계측 시스템을 이용한 유기중 코로나 방전의 전계변화 측정 및 비교분석

Abstract

Since more than two decade, the convential PD detecting systems have been employed in order to detect the pratial discharges occurring inside the HV power apparatus for their diagnosis by use of different type of detection such as accustic and UHF detection method. Regardlessof their wide on-site application, a certain number of technical inconveniences have been disclosed as follows : multistage amplification, large volume, susceptible to external noise and high price. In this respect, the optical measurement techniques are widely proposed in these days in this concerned field ascribed to the following advantages, : immune to external EMI noise and broad band reponse of the Pockels cellcoverinf frm DC to GHz. However, the reliability of several proposed techniques enabling to measure the electric field inside the large high power apparatus has not yet benn well approved. In this work, an optical measuring system, based on the Pockels effect, has been developed for measuring the field variation due to the corona discharges occurrinf in air and in oil. This system consists of He-Ne laser, single mode optical fiber, multi mode optical fiber, polarizing film, Y-cut LiNbO3 cell, photo detector, digital oscilloscope and personal computer with GPIB. For ths purpose, optical probe has been specially designed and realized and put into the needle-plane electrode. Afterward, same measurement is carried out in oil. We demonstrate the characteristic of the optical measuring system and the measurement results.