Study On Non-contact Detection For Faulty Insulators

The faulty insulator may harm the safe operation of the electric power system. At present, there is no mature or reliable method for faulty insulator detecting in China or abroad, especially for live line work. In this paper the author gives a research on the electric-field measurement method and UV pulse method based on non-contact mode to detect faulty insulator.Firstly, the non-contact electric-field measurement method is introduced. In this method, the electric-field intensity of a few points near the chain insulator is measured. The equivalent mode and the equations set are established based on the size, shape and position of the measured insulator as well as the basic principle of charge simulation method, so that the presupposed voltage distribution of the insulator chain can be dealt with a traversal calculation. The theoretical electric-field intensity at the detected points could be gained through the solution of the analogue electric charge. By comparing the theoretical and the measured value of the electric-fiend intensity till the requirement on errors is satisfied, the actual value of distribution voltage for the insulator chain could be gained. We can estimate whether there is faulty insulator and where by comparing the actual and the measured value of the distribution voltage. By this method, we can find faulty insulator from only a few measure points without contacting the insulator. To detect 110 kV line insulator chain, only 3 points will be measured with a maximum measure distance of 2m. Considering the high cost for the detector of non-contact electric-field measurement method, it is difficult to be promoted extensively. So a new method named non-contact UV pulse method is presented on the base of the non-contact electric-field measurement method.Secondly, this paper introduces the principle of UV pulse method. The faulty insulator may cause change to the voltage distribution of the insulator chain, which will lead to change to the surface air discharge strength of the insulator. The varity rate of discharging pulse number would rise significantly (more than 10% for 110 kV insulator chain), and in extreme cases it could reach more than 100%. The insulation status can be determined by detecting the change of solar blind UV radiant intensity caused by the surface corona discharge of the insulator.Thirdly, this paper studies'UV-1'UV pulse measure equipment based on UV pulse method. It can effectively detect faulty insulator of different voltage classes by detecting...