高压电缆铝套结构与缓冲层烧蚀特性

Ablative Properties of Buffer Layer in Aluminum Sheath Structure of High Voltage Cable

近年来,皱纹铝套型高压交联聚乙烯(cross-linked polyethylene,XLPE)电缆在运行中多次发生缓冲层烧蚀故障。相对皱纹铝套,平铝套与缓冲层的电气接触更好,在抑制缓冲层烧蚀故障方面的表现是否更好是一个值得研究的问题。为此从径向电流集中导致烧蚀的角度,考虑重力影响,通过有限元仿真和模拟烧蚀试验对2种结构进行对比研究。结果表明:与皱纹铝套相比,重力影响下的平铝套与缓冲层有更大的接触面积,分散了接触不良导致的径向集中电流,有效降低缓冲层的温升;在100 mA试验电流条件下,皱纹铝套结构的缓冲层温度>278℃,甚至烧穿缓冲层,灼伤绝缘屏蔽,而平铝套结构的缓冲层温度仅为74℃。与皱纹铝套结构相比,平铝套结构在抑制缓冲层烧蚀方面具有优势。

In recent years,the buffer layer ablation failure has occurred many times in the operation of corrugated alu-minum sheath structure HV XLPE cable.The electrical contact with buffer layer of flat aluminum sheath is better than that of corrugated aluminum sheath,whether it has better performance in inhibiting the ablative failure of buffer layer is a problem that is worth studying.In this paper,considering the influence of gravity,based on the ablation mechanism of ra-dial current concentrated,the two structures are compared and analyzed by finite element simulation and simulation ablation experiments.The results show that the contact area between the flat aluminum sheath and the buffer layer under the influence of gravity is larger than that between the corrugated aluminum sheath and the buffer layer.The concentrated radial current caused by the bad contact is dispersed,and the temperature rise of the buffer layer is effectively reduced.Under the test current condition of 100 mA,the buffer layer temperature of corrugated aluminum sheath structure exceeds 278℃,and even the insulation shield is burned,while the buffer layer temperature of flat aluminum sheath structure is only 74℃.Compared with the corrugated aluminum sheath structure,the flat aluminum sheath structure has an ad-vantage in inhibiting the ablation of buffer layer.