Analysis of PD spectrums in high voltage apparatus insulated with compressed gas

The paper presents a set of the curves about PD spectrums in the high voltage apparatus insulated with compressed air gas in the different pressures, which are measured with the UHF method. The aims of the research work are to reveal the essence characteristics of the compressed gas PD. To carry out the research work, the experimental models are designed according to the typical structures of the high voltage apparatus insulated with the compressed air gas. The PD phenomena are appeared absolutely on the spaces between the electrodes because the failures brings about when the insulating weak existing, for example, a free metallic particle can attracted to the HV conductor and produce micro-discharge that triggers breakdown. Other causes of failure are discharges from any stress-raising protrusion, capacitive sparking from an electrode which is not properly bonded to either the HV conductor or ground, and so on; and the common feature of all these defects is that they generate PD activity in advance or complete breakdown. The research results are necessary for detecting failures on the high voltage apparatus insulated with compressed air gas and have practical significance.