Abstract
Many studies on arc deterioration of electrical insulating materials by high voltage-low current arc have hitherto been done by using small size samples with electrodes having short gap length. In this paper, the arc resistance tests different from the previous ones were carried out by applying higher voltage and longer electrode gap length than before. Arc resistance was measured by a new arc resistance test method and the process of arc deterioration was investigated.
As the experimental method, ASTM D495 standard test method was modified a little. Electrodes were the stainless steel plate type of 5-100mm in length and the applied voltage was max. 100kV. Furthermore, arc resistance in the case of electrodes detouched from the sample surface was also investigated.
The experimental results are summarized as follows:
(1) The arc resistance of insulating materials measured with contact electrodes having long gap length showed two different tendencies depending upon the species of insulating materials, one showing a slow increase with increasing gap length from about 40mm to 100mm, and the other a tendency of saturation at the gap length of 50mm or more. Thus, the effect of electrode gap length on arc resistance was observed clearly.
(2) The arc resistance of insulating materials measured with detouched electrodes having long gap length also showed two different tendencies depending upon the species of insulating materials, one showing a slow increase with increasing gap length from about 30-40mm to 100mm and the other nearly constant. Thus, the separation of electrodes from the sample surface affected arc resistance remarkably and the effect of electrode gap length on arc resistance was observed in this case also.
(3) The effect of spatial configuration of sample on the arc resistance of insulating materials exists not only in comparatively small electrode gap length but also in long one.
