Abstract
Epoxy resins are widely used as the constitution materials of various electrical apparatus because of their good physical properties. Arc resistance of epoxy resin is an important factor for their use in electrical apparatus subjected to arcing condition. Although arc resistance of epoxy resins cured with sole curing agent has hitherto been investigated fairly well, few studies have been made on the effect of composite curing agents. Such studies are considered desirable because epoxy resins with good arc resistance may be obtained by using two or more composite curing agents and the results will help to establish the mechanism of improving the arc resistance from the standpoint of composite dielectrics.
In this paper, the ASTM D495-71 arc resistance test was carried out by using epoxy resins with various composite curing agents, and the effects of composition, especially those of species of curing agents, ratio of mixture, etc. were investigated.
The results showed that three cases appeared when two or three composite curing agents were used: the case with higher arc resistance than that with sole curing agent, the case with lower arc resistance and the case with the average arc resistance of those with sole curing agents. The difference in change of arc resistance was also observed depending upon the species of epoxy resins used. The thermal, mechanical and other properties were taken into account to evaluate those with improved arc resistance, and it was found that the epoxy resins cured with the composite curing agents are good enough for practical use.
