Abstract：The foreign scholars indicated that the X-ray could conspicuously excite partial discharge (PD) of tiny air voids in solid insulation. In order to probe into the practicability of this method for needle discharge in SF6, a PD test platform based on real 252 kV gas insulated switchgears (GIS) was built and the common needle discharge model in GIS was designed. Then, through the ultra-high frequency (UHF) method, the discharge characteristics of the needle discharge model under the direct current (DC) voltage induced by X-ray were measured. The PD tests were based on the specific needle defect with 50μm curvature radius and 15mm length. The results show that X-ray can reduce the partial discharge inception voltage (PDIV) by about 28.6% and 15.6% under positive and negative DC voltages, significantly increase discharge counts for about 5.3 to 17.0 times under positive voltage and about 80.4 to 166.7 times under negative voltage respectively, and reduce the UHF signal amplitude by about 35.3% under positive voltage. Finally, the possible mechanism is that X-ray can ionize SF6 near the needle and the photoionization can provide sufficient electrons, which will reduce the time lag of gas discharges and lower the PDIV correspondingly. The results show that the PD in SF6 can be regulated by the X-ray and this method is meaningful to the detection of insulation defects in DC GIS and GIL.
张强, 张瀚驰, 李成榕, 马国明. X射线激励对SF6中直流针尖放电的影响[J]. 电工技术学报, 2019, 34(24): 5282-5288.
Zhang Qiang, Zhang Hanchi, Li Chengrong, Ma Guoming. Impact of X-Ray on Needle Discharge in SF6 Under DC Voltage. Transactions of China Electrotechnical Society, 2019, 34(24): 5282-5288.
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2019, Vol. 34 
