Electrical insulation performance evaluation of PVF wire under thermal and electrical accelerated aging

It is crucial to understand degradation factors under actual operation in the lifetime evaluation of the coil winding of transformer. Polyvinyl formal (PVF) wire is used in oil-immersed transformer. Main degradation factor is considered to be oxidation and damage of the insulation coating due to thermal stress and partial discharge (PD). This paper deals with electrical insulation performance evaluation of twisted-pair specimen with PVF wire after thermal and electrical stress in the insulating oil. This research also deals with evaluation of a relation between the thermal stress and PD inception voltage (PDIV). Furthermore, Voltage-time (V-t) characteristics of twisted-pair specimen is investigated.