高压电缆缓冲层烧蚀及白斑模拟试验研究

Study on Simulation Experiment of Ablation and White Powder of Buffer Layer in High-voltage Cable

近年来,高压电缆半导电缓冲层因烧蚀、白斑引发故障频发,为研究并验证诱发因素,通过制备相应结构的成品电缆长期带电运行,进行间隙放电、接触不良电容电流烧蚀、白斑形成等多项试验模拟并开展分析。结果表明:高压电缆在正常运行状态下的电容电流热效应不足以引起半导电缓冲阻水层烧蚀,而是由电容电流和半导电缓冲层与铝护套之间的局部放电共同作用导致,半导电缓冲层受潮后起始烧蚀电流、时间明显降低;半导电缓冲层与铝护套存在较小间隙时会诱发局部放电,但随着间隙增大,内部电场强度减小,无法检测到局部放电。白斑是阻水粉和氧化铝的混合物,半导电缓冲层受潮是带材表面产生白斑的重要因素。

In recent years,the semi-conductive buffer layer of high-voltage cable has frequent faults caused by ablation and white powder.In order to study and verify its inducing factors,a number of tests such as gap discharge,poor contact capacitor current ablation and white powder formation were simulated and analyzed by preparing the finished cable with corresponding structure for long-term live operation.The results show that the thermal effect of the capacitive current in the normal operation state of the high voltage cable is not enough to cause the ablation of the semi-conductive buffer water blocking tape,which is caused by the combined action of the capacitive current,semi-conductive buffer layer and the partial discharge between the semi-conductive buffer layer and the aluminum sheath.The initial ablation current and time decrease significantly after the semi-conductive buffer is affected with damp.When there is a small gap between the semi-conductive buffer layer and the aluminum sheath,the partial discharge is induced,but with the increase of the gap,the internal electric field strength decreases,and the partial discharge can not be detected.The result also indicates that the white powder is a mixture of waterproof powder and alumina and the damp of semi-conducting water blocking tape is an important factor to produce white powder on the surface of the material.