Abstract
The study of the arc resistance of synthetic resin in insulating liquids has, scarcely been carried out systematically in the past. Even the test method has not been established yet, and the arc resistance in insulating liquids is usually assumed from the data of the arc resistance in air.
In this paper, the arc resistance tests were carried out in various insulating liquids such as transformer oil, silicone oil, etc. to investigate the fundamental properties of arc resistance of systhetic resin in insulating liquids. Then, the effect of the difference in insulating liquids on the arc resistance and the effect of the existence of insulating liquids on the process of arc deterioration were discussed. Furthermore, the effects of the sample size and the geometrical form in the arc resistance test in insulating liquids were investigated.
As the test method, ASTM D 495 standard method was adopted with some modifications. The applied voltage was as high as 45kV, because of need of arcing in insulating liquids. The electrode gap length was 5mm. The arc resistance was obtained in various insulating liquids for various synthetic resin samples.
The experimental results showed that there was no coincidence between the arc resistance of synthetic resin in air and that in insulating oil, and the estimation of arc resistance in insulating oil from that in air was generally difficult.
It was elucidated that the arc resistances of various epoxy resins in insulating oil gave generally a convex or concave whenplotted against the amount of amine type or acid anhydrous type curing agent as same as in air.
Furthermore, the arc resistance of synthetic resins were influenced by the kinds of insulating liquids and they were good in transformer oil and in xylene but bad in silicone oil.
The sample size effect on the arc resistance of synthetic resin in insulating oil was not observed at least in 2∼7mm of electrode gap length. However, it was clarified that the effects of spatial configuration and geometrical form existed.
