Study of breakdown characteristics of solid insulator under different length of high voltage pulses

Summary form only given. The breakdown characteristics of solid insulator with two different geometries (a taper insulator and a recessed insulator) are tested under high voltage pulses with two different pulse width (90 ns and 140 ns). The effects of the angle between the solid insulator and the metal electrode and the length of the pulse on the electric field and the breakdown voltage have been investigated both by computation and experiments. The ANSYS code was used to calculate the electric field between the two electrodes and the gas-insulator-electrode triple junctions. The voltage pulse used for testing is produced by a triggered Marx generator capable of 300 kV output with a rise time of 25 nsec and a pulse length of about 320 nsec. The Marx is made up of six capacitors and three gas insulated three-electrode spark gaps arranged in omega-type. In this arrangement, the gaps can trigger in a wide voltage range from 8 kV to 30 kV and the operation was more reliable. Two different length cables used as pulse form line (PFL) to produce different length of pulses. The measurements show good qualitative agreement with the results from computation.