石墨基柔性接地体动热性能优化试验研究  

Experimental study on dynamic and thermal performance optimization of graphite based flexible grounding electrode

作　　者：张国锋 吕坤阳 张明磊 务孔永 Zhang Guofeng;Lyu Kunyang;Zhang Minglei;Wu Kongyong(Henan SIDA Power Equipment Co.,Ltd,Xuchang 461500,China)

机构地区：[1]河南四达电力设备股份有限公司,许昌461500

出　　处：《电子测量技术》2020年第16期17-21,共5页Electronic Measurement Technology

摘　　要：为提高石墨基柔性接地材料的电气性能和承受短时工频故障大电流的能力,提出了在内层将导电性和耐腐蚀性好并经过防腐处理的无氧紫铜丝均匀分散到石墨基柔性接地材料中,外层采用降阻性能优异的柔性石墨线编织成散流面的复合型石墨接地体结构;通过短路热稳定试验模拟系统短路故障发生后,在输电线路断路器动作前短路电流流过带金属芯复合型石墨基柔性接地体的情况,考核试验前后复合材料的电气特性和对动热效应的承受能力。结果表明:铜丝直径为0.3和0.6 mm复合型石墨接地体的电阻率分别为1.82×10-6Ω·m和4×10-7Ω·m;试验完成后,观察复合接地体的外观,其表面仍呈现编织形网格状,并无断股、烧蚀、鼓胀等缺陷,在5000 A短路电流的作用下,直径为0.6 mm铜丝的复合接地体表面最高温度达到了161℃,且材料内部伺服的金属芯表面无氧化、断裂等现象,拟合温升曲线的坡度也比较小,试验前后复合接地体的单位长度直流电阻变化率小于20%。In order to improve the electrical performance of graphite based flexible grounding material and its ability to withstand large short-time power frequency fault current, this paper proposes that the oxygen-free copper wire with good conductivity and corrosion resistance and anti-corrosion treatment be evenly dispersed into the graphite based flexible grounding material in the inner layer, and the flexible graphite wire with excellent resistance reduction performance is used in the outer layer to weave the composite graphite grounding body. The short-circuit thermal stability test simulates the situation that the short-circuit current flows through the graphite based flexible grounding body with metal core before the circuit breaker acts after the short-circuit fault of the system occurs, and the electrical characteristics and bearing capacity of the composite material to dynamic thermal effect before and after the test are evaluated. The results show that the resistivity of composite graphite grounding body with copper wire diameter of 0.3 and 0.6 mm is 1.82×10-6 Ω·m and 4×10-7 Ω·m, respectively. After the test, the appearance of the composite grounding body still shows the braided grid shape, and there are no defects such as broken strand, ablation and bulge. Under the action of 5 000 A short-circuit current, the maximum surface temperature of the composite grounding body with 0.6 mm diameter copper wire is obtained at 161 ℃, there is no oxidation, fracture and other phenomena on the surface of the metal core, and the slope of the fitting temperature rise curve is relatively small. The change rate of DC resistance per unit length of composite grounding body before and after the test is less than 20%.

关 键 词：工频电流 短时故障 热稳定 柔性石墨 电气测量 散流 

分 类 号：TM89[电气工程—高电压与绝缘技术]