Study on the influence mechanism and regulation of large suspended potential conductor on impulse discharge characteristics of air gap operation
The paramount reason for the malfunction of a center connecting joint,where considers to be the major fault point of power cables,is construction deficiencies. As a result,a three-dimensional finite element model is generated in order to evaluate hazards of the construction deficiency towards the intermediate joint of the cable. Furthermore,this article analyzes the patterns of electric field distribution when three kinds of construction-deficiencies occurs including uneven application of silicone grease,scratches on the surface of major insulation and moisture into the intermediate connector. The last but not least,the article explores the relation of the fault location to the field strength. Additionally,a platform for partial discharge test in the context of alternating voltage is established for verifying samples. The results show that the most significant electric field distortion appears when the silicone grease is unevenly applied and the air gap emerges near the stress cone. While oppositely,the field strength decreases gradually when the air gap position is away from the stress cone. Besides,the most serious electric field distortion is visible while the major insulation has scratches. Also the field strength is maximized at the cut-off of the outer semi-conducting layer. Moreover,the most intense electric field distortion arises from when water membrane is close to the stress cone due to moisture ingress into the joint. In addition,numbers of discharge increase successively in the partial discharge test conducted at the same voltage and under the circumstances of above mentioned three kinds of construction deficiencies.