Impulse waveform effects on negative point voltage/time characteristics in gamma irradiated SF/sub 6/

Comparative time lag measurements were conducted for a point-to-plane geometry at 0.1 and 0.2 MPa using both steep-fronted impulses and lightning surges over the time scale 10 ns to 1 ms. The time scale over which breakdown occurs under low overvoltages was found to be the most basic difference between the two responses. Statistical analysis of the terminal measurements revealed a transition in the distribution of failure times from one population to another. The transition was pressure and waveform dependent. Corona stabilization was shown to generate a distinct anomaly in the voltage/time curve for the lightning surge which was not mirrored in the characteristics generated under the steep-fronted impulse application. Fast rising surges did not cause anomalous behavior in the voltage/time characteristics over the nanosecond region, and were not inducive to stabilization like long-fronted impulses.<
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