Research of insulation properties of polymer materials using in oil-filled transformers under high temperature

Traditionally, oil-filled transformers have utilized densified cellulose paper as the primary conductor insulation. However, cellulosic insulation is a relatively low temperature material and thermal degradation due to overload conditions and long-term aging can lead to transformer failures. In order to improve the structure and insulation performance of oil-filled transformers, this paper choose 4 insulation materials with special applications to research, electrical properties of polymer before and after aged under 130°C at different times have been examined, the examined dielectric parameters are dielectric constant, dissipation factor and ac electric breakdown strength. The characteristics of dielectric constant and dissipation factor versus temperature before and after aged under 130°C at different times have been analyzed. Preliminary results show that PTFE and Polycarbonate are ideal substitutes of cellulose paper.