PD time sequential and light emission properties as pre-breakdown phenomena of SF/sub 6//N/sub 2//CO/sub 2/ gas mixture

This paper describes partial discharge (PD) properties of the SF/sub 6//N/sub 2//CO/sub 2/ ternary gas mixture which has higher breakdown voltage than an SF/sub 6//N/sub 2/ gas mixture by composing CO/sub 2/ and N/sub 2/ with a suitable rate. PD time sequential properties under a positive DC voltage application and PD light emission properties under a positive lightning impulse voltage application are investigated to clarify the effect of adding CO/sub 2/ from the viewpoint of pre-breakdown phenomena. Based on the PD phenomena, we discuss the mechanism of an increase in breakdown voltage due to the addition of CO/sub 2/.