Influence of pressure and humidity on the amplitude — Phase distribution of AC corona pulse

Corona problem is one of the important problems in the design and operation of the transmission lines. The corona discharge of high voltage transmission lines, results in power loss, radio interference and audible noise, which become more serious at the high altitudes. Besides, it has a great influence on the safe and robust operation of high voltage apparatus. A study carried out in the chamber made of perspex, was that AC corona characteristics varied with air pressure and humidity through the rod plane electrodes. The experiments showed that the inception voltage of AC corona was reduced with air pressure decreasing or humidity increasing. Meanwhile, the amplitude - phase distribution of AC corona pulse was displayed under different air pressure and humidity. Under low humidity (RH=25% or 55%), the streamer pulses only appear in the rise edge of positive half cycle, and the number of streamer pulses is few. The negative streamer pulses occur around the peak value of the negative half cycle. The streamer pulses appear in the rise and fall edge of positive half cycle at the same time with high humidity (RH=85%), and the number of streamer pulses increases obviously. When the humidity is higher (RH=95%), the streamer pulses appear only in the fall edge of positive half cycle. Furthermore, the negative streamer pulses around the peak of the negative half cycle also disappear.