Experimental Study on Relations between Non-ideal Surface Morphology with Corona Onset Voltage of Grading Ring

In order to deeply study the relations between non-ideal surface morphology with corona onset voltage of grading ring, a series of experiments are proposed based on the established experimental platform testing corona onset voltage of grading ring. By comparing the corona onset voltage of grading ring of cone, cylinder and hemisphere convex morphology, it is found that cone has the most significant effect on corona onset voltage reduction of grading ring. Then, four kind of experiments are implemented according to the different morphological characteristics of cone, such as the distribution location of a cone, the distance between two cones, the cone numbers per unit length, and the apex difference of adjacent cones. The results show that when the cone is closer to the outside of the grading ring, the corona onset voltage decreases greater; when the distance between two cones changes from small to large, the corona onset voltage decreases gradually, and when the distance is greater than a certain value, two cones start corona almost independently; when the cone numbers per unit length increases, the corona onset voltage increases and tends to be stable; the corona onset voltage of grading ring decreases with the increase of the apex difference of adjacent cones on its surface. The research results have supplied the quantitative relations between non-ideal surface morphology with corona onset voltage of grading ring. They can be utilized to analyze the corona reason of grading ring, monitor the surface situation online and make corresponding anti-corona measures.