X-ray induced partial discharge phenomena in cavities and transformer oil

Partial discharge detection sensitivity is often limited by the availability of electrons necessary to initiate discharge. With X-ray irradiation, some interesting PD phenomena were found in cavities of solid dielectrics and in transformer oil in the authors´ laboratory tests. For small cavities, PD measuring sensitivity can be increased greatly with the use of X-ray irradiation and the effect of X-ray irradiation on PD measuring sensitivity is decreased with the size of cavities. In transformer oil, X-ray induced PD was found to be much more active compared to conventional PD under the same electric stress, which may indicate that X-ray induced PD measuring technique can be applied to oil/paper systems, such as those used in transformers