Properties analysis of insulation breakdown by thermal degradation test for insulation papers

In this paper, the accelerated thermal deterioration test was carried out in order to evaluate the characteristics of the insulation breakdown of the insulating paper used in the oil type transformer. Characteristics of the insulation breakdown due to the thermal stress of the insulating oil-impregnated insulating paper were analyzed. The insulation materials used in tests were three types of aramid papers. Which was widely used as the main coil insulation of the transformer. And silicone oil, which was synthetic insulating oil was used. Accelerated thermal deterioration test was conducted by IEEE/ANSI Standard C57.91-based on the life expectancy curve of 1981, the H class insulation system was used as a reference in order to comply with main transformer of AC electric multiple unit. The thermal stress did at 40°C ~180°C and the insulation breakdown characteristics of the insulating paper were test. For the analysis, the strength of insulation breakdown depends on the temperature.