Influences of voltage waveforms on very low frequency (VLF) partial discharge behaviours

Very Low Frequency excitation is an alternative method of continuous AC high-voltage testing that overcomes the problem of large reactive power requirement associated with testing at normal power frequency (50/60 Hz). However, for partial discharge diagnostic testing and in particular under very low frequency sinusoidal voltage excitation, it has been found that the test results are different from those performed at power frequencies. On the other hand, partial discharge tests under standardised cosine-rectangular voltage waveforms give similar patterns when they are compared with results at power frequency. In this paper, the influences of excitation voltage waveforms on partial discharge characteristics at very low frequency are studied. Various voltage waveforms including sinusoidal,…