Study on the Damp Heat Aging Performance of Encapsulated Insulation in Ultra High Voltage Dry-type Parallel Reactors

The 500kV dry-type hollow reactor operates outdoors for a long time, and the encapsulated insulation is easily exposed to humid and hot environments. Epoxy resin is one of the main materials for the encapsulated insulation of dry-type hollow reactors. Studying the single thermal aging and humid and hot aging performance of epoxy resin and encapsulated composite insulation can provide reference for optimizing equipment insulation materials and improving operational reliability. This article conducted non-destructive electrical performance testing and power frequency breakdown voltage testing on a 500 kV dry-type hollow core reactor filled with epoxy resin samples, and studied the electrical performance changes of the epoxy resin material after single thermal aging and wet heat aging. The wet heat aging test adopts the PCT accelerated wet heat aging method. The results showed that the mechanical properties of epoxy resin materials used for joint filling significantly decreased after thermal aging at 220 °C, making them more prone to brittle fracture under electric force, indirectly reducing the breakdown voltage of the material. After 1 hour of damp heat aging, the breakdown voltage decreased by 60.3%; After 5 hours of drying, the breakdown voltage can be fully restored. This article also studied the changes in electrical performance of dry-type shunt reactor wire rods in humid and hot environments. The results showed that after 6 hPCT humid and hot aging, the dielectric loss of the wire rods increased by 178% and the breakdown voltage decreased by 20%.