II. TEST
The breakdown voltage test of impregnated paper insulation
refers the standard of IEC60243-1 Electrical Strength of
Insulating Materials-Test Methods-Part 1 and GB/T1408-
2006 methods of test for electric strength of solid insulating
materials. Test electrode is designed is in accordance with the
procedures of ASTM-D149-81. Test electrode structure is
shown in figure 1. The surface of copper electrode is polished,
and the end is in the shape of fillet whose r=3mm. High
voltage electrode is a cylinder whose diameter is 25mm and
height is 25mm. The low voltage electrode is a disk whose