Electrical breakdown of small air gaps bounded by dielectric surfaces using 500/3000 μs surges

Measurement of the 50% impulse-discharge stress, the apparent discharge magnitude and the total time lag of discharges in air-filled cavities in polythene, using 500/3000 μs surges, is described. The discharge stress is lower and the total time lag greater than with 1/50 μs impulses. With repeated discharges, both are reduced.