Results from the UHF sensor show that PD events in point cathode consist of a train of single pulses with ascending magnitude which cannot be resolved by the lower bandwidth of standard capacitive coupling circuits. Meanwhile, during positive discharges, only one single event is seen with much higher magnitude than negative discharges. These results are in line with previously published observations [3].
It is difficult to quantify PD magnitude from UHF mea- surement due to the variability in the energy received by the sensor. This is thought to be because of the chaotic behaviour of charge dynamics during streamers, which results in the variability of the UHF pulse shapes. Further study is required to confirm this hypothesis.