Study on Corona Onset Voltage of Parallel Rod Electrodes under AC-DC Combined Voltage

To study the influence of climate factors on corona discharge under AC-DC combined voltage, it is required to build an artificial climate chamber. AC and DC voltage will be introduced into the chamber by parallel wall bushings. To prevent corona discharge between the bushings, the variation law of corona onset voltage of parallel rod electrodes under AC-DC combined voltage should be explored. Four-channel acquisition card and low potential measurement method were ultilized, rod radius, distance between two rods and AC/DC ratio were changed to get the corona onset voltage. The corona onset voltage at DC side and AC side both increased with the increase of rod radius and the distance between two rods. Under the same fixed voltage component, the order of the corona onset voltage from the largest to the smallest is: the negative half cycle corona at AC side, the positive half cycle corona at AC side, the negative corona at DC side, and the positive corona at DC side. Therefore, it is particularly important to pay attention to the situation where positive DC-AC voltage is introduced, and the corona discharge is most likely to occur at DC side.