Abstract
This paper proposes the quantitative estimation method of negative polarity sparkover voltage and time (V-t) characteristics based on the optical observation of the discharge development process. The optical observation result was obtained in SF6 at 0.1MPa under quasi-uniform field gap (g=80mm) with steep-front square impulse and fast-oscillating impulse voltages. We modeled the discharge development processes with streamer development, leader conversion and leader development and evaluated parameters by the electric field respectively. The streamer development process is different between non-oscillating impulse (square impulse) and fast-oscillating impulse based on optical observation result, we took into consideration the influence of voltage oscillation. As a result, it was obtained that calculation methods of the V-t curve in SF6 are proposed and their applicability to the evaluation of actual V-t characteristics is verified. These methods can be used to predict V-t curves for other voltage waveforms having an arbitrary rise time.
