Measurement and simulation of charge accumulation on a disc spacer with electro-thermal stress in SF6 gas

The problem of surface charge accumulation on a gas-spacer interface is one of the critical factors that limits the application of DC gas-insulated transmission lines (DC GIL). In previous works, the models of surface charge accumulation under different temperatures on a spacer were investigated. However, these simulation models lacked experimental verification. In this paper, a coupled electro-thermal field simulation model for charge accumulation on a spacer under DC stress is introduced, and an experimental platform with the ability to load the thermal field on a spacer is built. Then, the effect of the thermal gradient on the surface charge of a spacer is investigated by measurements and simulations. The results indicate that for the spacer sample in the experiment, the average surface potential increased 277 %, and the variation range of that increased 309 % as the conductor temperature increased from 303.2 to 343.0 K. The coupled electro-thermal field simulation model of charge accumulation on a spacer under DC stress was verified by experimental results. The simulation model will hopefully be helpful for the insulation design of DC-GIL.