Figure 9 shows the breakdown voltage versus humidity for the short rod/rod gaps at 60 Hz and 30 kHz. For gap lengths up to 30 mm, no corona was seen. Corona in the form of a glow was observed for the 45 mm gap. Due to voltage source limitations, the breakdown experiments for the 30 and 45 mm gaps at 30 kHz could not be performed. It can be observed that there is no significant variation on the breakdown voltage