Very low frequency (VLF) breakdown of air in non-uniform fields for varying humidity conditions

The effect of humidity on the breakdown voltage of air for frequencies in the kilo-Hertz range is largely unknown, especially for larger dimensions. This is of interest for high-power communication towers that can operate in a variety of climates. The very low frequency (VLF) and low frequency (LF) bands are used for long distance communication in the range of 10-30 kHz and 30-100 kHz, respectively. Results are reported for rod/rod gaps and rod/plane gaps in the range of 125-1000 mm at a frequency of 30 kHz. The breakdown voltage at 30 kHz is observed to be markedly lower than that at 60 Hz for non-uniform field configurations with corona pre-discharges. Electric field calculations have been completed for the experimental configurations to attempt to explain the difference in breakdown voltage.