Light Emission Spectrum Depending on Propagation of Partial Discharge in SF6

An understanding of mechanism of partial discharge (PD) in SF₆ gas is critical for diagnosis of PD in electric power equipment. Moreover, analysis of PD mechanism contributes to the optimization of the design of electric power applications. For these reasons, we study in detail about PD mechanism by measuring light emission spectrum of PD in SF₆ gas. In this paper, under an application of lightning impulse voltage in needle-plane electrodes, we have measured light emission spectrum of leader discharge. As the result, we have found out the light emission of long wavelength above 560 nm in leader discharge, and the light emission above 560 nm is emitted in the streamer head generated at the tip of the leader channel and radiated from dissociation products depending on the step propagation of leader discharge. These results suggest that we can diagnose the PD propagation in SF₆ gas and estimate the risk of breakdown (BD) by measuring PD light emission spectrum in electric power equipment. There are possibilities to contribute to enhance performance of the diagnosis technique in gas insulated power equipment.