Effect of Corona on Travelling Waves

Abstract

A NEW phenomenon of impulse corona has been observed with voltage waves of relatively long wave-fronts on a 33-kV. overhead line. The wave-shape at the sending end is 5.7/19.3 µsec. nominal. The accompanying oscillograms show typical waves recorded at a point 2.08 miles away. As the voltage exceeds the corona threshold, the wave-front shows the well-known phenomenon that part of it is sheared off due to corona losses. However, the voltage clearly recovers before its peak value is reached whereas previous observations made with wave-fronts of 1.5 μsec. or less show that this shearing effect extends to the wave tail. After the tests on which this communication is based had been completed, it was found that this recovery of voltage had also been observed by Mita and others¹ on a model line with waves of 2.2 and 4.2 µsec. fronts. As can be seen from the oscillograms, the rate of recovery is much faster for a negative wave than for a positive wave.