Experimental study on the relationship between partial discharge and gas decomposition products in SF6 insulated electrical equipments

SF6 decomposition serves as an effective means for online fault detection and diagnosis of SF6 insulated equipments. The relationship between SF6 decomposition products and partial discharge (PD) in SF6 insulated equipments remains a significant theoretical and practical issue to be addressed. Based on the simulations of protrusion discharge, floating discharge and surface discharge in SF6 insulated equipments, the present experiment studied the impacts of differentiated PD patterns, PD severities and SF6 pressures on the concentrations of SF6 decomposition products as well as the change in concentrations over time. The experimental results indicate that three kinds PD pattern discharges produce SOF2+SO2 and HF, the concentration of the SOF2+SO2 being always higher than HF. Generation of both gases increase with voltage application time; The concentrations of SOF2+SO2 and HF differ from differentiated PD discharge strength, and increase as discharge strength ascends; A negative relationship exists between SF6 gas pressure and the generation speed of SOF2+SO2 and HF. It is concluded that SF6 decomposition products, SOF2+SO2 and HF in particular, could be used as a means for on-line PD faults detection and diagnosis.