A study of large current interrupting capability of SF/sub 6//N/sub 2/ mixtures

This study aims to analyze the performance of the SF/sub 6//N/sub 2/ mixtures that can be a substitute for SF/sub 6/ in gas circuit breaker (GCB). The interrupting capability of SF/sub 6//N/sub 2/ mixtures were verified in real GCB with N/sub 2/ percentage varying from 0 to 50%. We carried out the current interrupting tests of SF/sub 6//N/sub 2/ mixtures by using a 170 kV puffer-type GCB at a laboratory. The results obtained from this study show that a 25% of N/sub 2/ mixture has an equivalent current-interrupting capability to pure SF/sub 6/ and a 50% of N/sub 2/ mixture has lesser capabilities. We will test a 75% of N/sub 2/ mixture soon and by using the test results, we develop a new-type interrupter of gas mixture.