抄録
Partial discharge (PD) degradation phenomena is one of the most important factor to decide the performance and the lifetime of the high voltage facilities. During the PD degradation tests of an epoxy specimen with a closed void, PD often change to a large number of very small PD known as swarming pulsive microdischarges (SPMD). The appearance of SPMD is concerned with the degradation of the insulating materials, therefore insulation diagnosis with the detection of SPMD become to be possible. However, SPMD can not be detected with the conventional PD detector because the PD magnitude of SPMD is too small. Authors has developed the computer aided partial discharge analyzing system (CAPDAS) to detect and analyze the SPMD. Furthermore, authors introduced a new PD parameter, the SPMD ratio, for the quantitative analysis of SPMD. In this paper, the time variation of SPMD characteristics of a CIGRE Method-II specimen are investigated by using the CAPDAS. Further, the effect of the frequency of the applied voltage on SPMD are also investigated at 60Hz and the very low frequency of 0.1Hz. As the result, the comparison of PD magnitudes measured at 60Hz with those at 0.1Hz could make a quantitative analysis of SPMD characteristics possible by using only the conventional PD detector.
