PARTIAL DISCHARGE PHENOMENA WITH X-RAY IRRADIATION IN OIL-GAP
GUO Lin 1, HUANG Xing-quan 2, LI Cheng-rong 3, ZHANG Yu-xiao 2 (1.Zhengzhou Electric Power College, Zhengzhou 450004, China; 2.Henan Electric Power Research Institute, Zhengzhou 450052, China; 3.North China Electric Power University, Beijing 100085
With conventional (PD) measurement technique, the tiny defects are difficult to be discovered in oil/paper insulation system. The partial discharge phenomena induced by X-ray irradiation in transformer oil-gap were investigated experimentally in this paper. It is found that PD activities in the oil-gap wrapped by insulating materials are enhanced under X-ray irradiation, which could be associated with charge injection and space charge distribution in the oil gap. Some free electrons could come from the HV metal electrode by Photon effect at metal electrode surface with X-ray irradiation, that is, free electrons in conductor could get energy from X-ray photons to leave the metal surface. The oil gap formed between the electrode and the wrapped cloths in the transformer model was small so that the electrons escaped from the electrode surface were limited in the tiny oil gap. Therefore a charge accumulation occurred in the oil gap, causing partial electric field stress intensified greatly. When the partial field was strong enough to ionize the oil, PD occurred in the oil gap with X-ray beam irradiation. This process resulting in PD occurrence with a lower voltage and an increase of PD amplitude and frequency is compared to that without X-ray irradiation, which was indicated in our tested results. The location of partial discharge signal because of X-ray beam irradiation and detecting partial discharge can been fixed on by modulating orientation of X-ray beam irradiation. The test results will be a basis to develop a new PD location technique by using X-ray beam irradiation to power transformer.
【CateGory Index】： TM855