Electrical discharge behavior of micro-gaps

Electrical discharge characteristics of micro-gaps, ranging from 50 to 1000 μm in air are investigated under ac, dc and high frequency (5 kHz) by using blade electrodes that possess a high aspect ratio: 20 μm edge thickness and 15 mm length. Three micro-gap configurations (single, series and parallel) are studied for the breakdown strength and partial discharge characteristics. An exponential increase in the breakdown strength with air gaps below 1000 μm is observed. The finite element models revealed that the electric stress at 1000 μm is about 4 times the applied field. The electric stress magnitude is found to reduce as a function of air gap up to about 100 μm where the actual field is equal to the applied field. The breakdown strength of the series gap configuration is significantly higher than that of the parallel configuration. The partial discharge activities are observed in the series configuration whilst the same is absent in the parallel configuration.