Effect of Rain Drops on Corona Discharge in Alternating Current Transmission Lines with a Corona Cage

Abstract

The dielectric distributed around the surface of electrodes has a significant effect on the corona discharge. Corona discharge in power transmission lines in fine weather is different from that in rainy days as the surface condition is greatly changed. The surface of conductors is filled with the drops of rainwater; hence, the electric field around the conductors will be distorted. The use of a corona cage is an effective and economical means for duplicating corona progress in power transmission lines with lower voltage on the conductor in the cage. The practical conductor was utilized in this experiment under both fine and rainy conditions. The process of corona discharge was recorded and investigated. It was found that the corona discharge turned to be much more intense when rain drops were enlarged and more compressed around the conductor. The corona inception voltage, which is an important parameter of corona discharge, was also gained using an ultraviolet imager (UV imager). The corona inception voltage under the rainy condition was about 25% lower than that under the fine condition. The results of the comparison of audible noise and radio interference were analyzed.