Purpose/Aim

Insulation systems integrating gas-solid interfaces may suffer from surface partial discharge activity, which gradually causes solid material degradation, associated with combined chemical and thermal effects, or even insulation failure due to the formation of spark or arc. An efficient and cost-effective design of insulation systems requires quantification of surface partial discharge inception characteristics.

Experimental/Modeling methods

Partial discharges (PD) on Polyethylene, Polyoxymethylene, Polyvinyl Chloride, and Polyamide insulating surfaces, were investigated by using a short sphere-plane gap stressed by positive ramp high voltages with variable rate of rise (50 – 1500 V/s). Inception probability distributions of surface partial discharge salient characteristics were obtained.

Results/discussion

Surface PD inception voltage is relatively unaffected by successive shots and decreases with higher material relative permittivity and for smaller sphere radius.

Conclusions

Surface partial discharge inception characteristics were investigated by stressing a short sphere-plane gap under positive ramp high voltages. There is a marked dependence of partial discharge inception voltage upon material relative permittivity and sphere radius.