高压电缆附件设计环节中几个关键问题探讨

Dealing With Some Key Design Problems in HV Cable Accessory

高压电缆附件的设计是一项涉及电气、机械、材料和热力学四方面的复杂过程,只有经过周密、精确的电、力、热的复合场设计,才能将因生产环节导致的故障率降至最低。因此针对高压电缆附件用预制或冷缩型附件设计环节中的几个关键问题,从电学性能、力学性能、松弛特性、扩张形变和电场优化等几个方面出发,提出橡胶材料弹性模量越高,界面压力越大,附件所需扩张率越低;温度越高,伸长率越大,橡胶材料的应力松弛速度越快;电缆附件撑开时,从内侧到外侧发生非线性位移,内侧大而外侧小,根据弹塑性力学理论,建立电缆附件的厚壁圆筒力学形变方程,可将电缆附件扩展后的电场优化尺寸成功恢复到厂家生产尺寸;最后给出合理设计电缆附件生产结构的方法和思路。该研究方法有望用于指导我国高压交、直流预制/冷缩型电缆附件的材料选型和结构优化设计。

The design of high voltage cable accessory is a complex process involving electric, machinery, material, and thermodynamics. The electrical, mechanical and thermal composite field is precisely designed to minimize the failure rate caused by production process. Consequently, we discussed several key design problems such as the electrical properties, mechanical properties, relaxation characteristics, expansion deformation and electric field optimization in high voltage prefabricated or shrinkable cable accessories. We proposed that accessories expansion rate would decrease with rubber elasticity modulus and increase of interfacial pressure, and rubber stress relaxation rate would increase with environment temperature and rubber elongation increasing. The expansion of the cable accessory brings a nonlinear displacement from the inside to the outside, and the inside displacement is large and the outside is small. Based on the theory of the elastic-plasticity mechanics, the thick-wall cylinder deformation equations of cable accessories were established. The production structure could be obtained by the relaxation process of the accessory, recovering from the expanded installation state after electrical field optimization. Finally, a reasonable method to design cable accessories production was proposed. The method is expected to guide the structure optimization design and material selection of high voltage AC and DC prefabricated/shrinkable cable accessories.