抄録
The effect of isolated small alien substances on the creeping discharge progressing the surface of the pressboard immersed in PFAE oil has been investigated using 1.2/1000 μs impulse voltages with ± 90 kVpeak in maximum. PFAE oil is new vegetable-based insulating oil which was recently developed as a substitute of mineral oil for environmental requirements. In this paper, it is shown that the creeping streamer is largely extended by the presence of isolated small alien substances in the surface or inside of the pressboard. The effect of such alien substances also appears in the streamer shape, discharge current and streamer velocity. These are discussed qualitatively on the basis of the experimental results.