Pre-breakdown phenomena in synthetic ester and silicone oils for power transformers
Résumé
This paper reports on the initiation and propagation of streamers in synthetic ester and silicon oils for power transformers. The study is carried out under dc voltage using a point-plane electrode arrangement. We especially analyze the initiation voltage of streamers as well as the associated current and light emitted by these streamers. The influence of hydrostatic pressure (PH) on these characteristic parameters is also investigated. It's shown that the initiation threshold voltage (Ui) of streamers is higher with a positive point than with a negative one whatever the liquid ; Ui increases quasi-linearly with PH. The values of U i are higher in silicon oil than in synthetic ester (tetraester).