Combined Effects of Humidity and Frequency on the Dielectric Strength of Air for VLF Applications

The paper reports the results to date from a study to investigate the effect of humidity and frequency on the breakdown of air. Experiments were conducted on Rogowski-profile uniform field gaps and non-uniform rod-plane gaps ranging from 4 to 52 mm. Results show that uniform field VLF (Very Low Frequency Radio; 10-30 kHz) breakdown voltages decrease with humidity, opposite to that observed at 60 Hz. Non-uniform field breakdown voltages at VLF are lower than those observed at 60 Hz, but have similar trends with humidity. Uniform and non-uniform field breakdown experiments have been completed at 60 Hz for validation.