182 / 2018-08-27 15:34:11

Partial Discharge Characteristic on Pressboard Surface in Needle-Plane Model Under Different DC Polarity

DC polarity,partial discharge characteristic,needle-plane model with pressboard,breakdown channel

The pressboards inside of converter transformers are subjected to AC and DC voltage during operation period. In order to have a further understanding of the pressboard performance under DC voltage, a needle-plane dcmodel with pressboard was established under laboratory conditions. The results show that the overall partial discharge concentrates on the moment before breakdown under the positive polarity, but the over partial discharge is more and more severe during the whole process of the test under negative polarity; the discharge channel passes through oil-paper insulation interface area at the breakdown moment, most of the channel is distributed in the insulating oil. The results can provide reference for the design of insulation structure of converter transformer.