Surface Flashover Characteristics of Ribbed Insulator in Cryogenic Environment

Conductive particles are inevitably caused by the installation, transportation, and operation of power equipment. These conductive particles are a major factor in the failure of electric insulation breakdown, and superconducting power equipment is no exception. It is apt to think that increasing the height of the insulator is the proper solution for securing the surface flashover strength. However, such a solution could cause size increment of the apparatus as well as cost growth. Therefore, in this paper, introducing ribs on surface of the insulator was considered as a solution for improving the tolerance toward conductive particles. Four types of specimens made of Teflon, with the same height, were fabricated to verify the influence of the rib on the surface of the insulator in liquid nitrogen. Furthermore, specimens with the same creepage distance were prepared to find out which is the dominant factor in improving surface flashover strength amongst introducing ribs or height when conductive particles exist. The test result showed that the highest specimen without ribs had the best tolerance toward conductive particles. However, considering the economic aspect, an increase in height leads to increase in cost. Therefore, introducing ribs on the surface of the insulator is a complementary solution to achieve both cost and insulation properties.