典型植被触400 V架空线路故障引燃试验分析

Experimental analysis of typical vegetation contact with 400 V overhead line fault ignition

为了研究植被触低压配电线路故障是否会威胁林区防火安全,搭建了一个400 V架空线路植被触导线故障模拟试验平台,选取了林区常见的雪松和凤尾竹作为典型的植被样品,同时为了补充试验数据,还增加了葎草和爬山虎进行试验。通过分析故障时流经植被的泄漏电流、植被的温升现象和植被表面的炭化痕迹来研究低压配电线路与不同类型植被接触引燃的可能性。研究表明:雪松触单相导线故障无明显温升现象;含水率高的凤尾竹触单相导线故障温升明显,故障点附近有明显的炭化痕迹,最高温度达到95.3℃时,最大泄漏电流为180 mA;电流的热效应在故障点累积,导致该区域的温度上升和水分蒸发。随着含水率的降低,水分蒸发对植被阻抗的影响逐渐增大,进而导致泄漏电流下降,最终使温度降低直至室温,因此,植被不会自燃,也无法通过电弧引燃附近易燃物,说明低压配电线路植被触单相导线故障不会威胁林区的防火安全。特殊情况下的凤尾竹跨接两相导线故障以及葎草和爬山虎跨接两相导线故障温升明显,且伴有放电现象,在一定条件下,可发展为相间短路,产生的短路电弧会引燃故障点附近的易燃物,威胁林区防火安全。研究结果对穿越林区的低压配电线路预防山火具有重要意义。

In order to study whether the vegetation contacting with the low voltage distribution line fault will threaten the fire safety in the forest area,a 400 V overhead line vegetation touching the conductor fault simulation experimental platform was set up,common cedar and phoenix tail bamboo in the forest area were selected as typical vegetation samples,and in order to supplement experimental data,humulus and ivy were also added for the experiment.By analyzing the leakage current flowing through the vegetation during the fault,the temperature rise phenomenon of the vegetation and the charring traces on the surface of the vegetation,we study the possibility of ignition of lowvoltage distribution lines in contact with different types of vegetation.The experimental study shows that:cedar contact singlephase conductor failure without obvious temperature rise phenom‑enon;high water content of the fenugreek contact single-phase conductor failure temperature rise obviously,there are obvious traces of charring near the fault point,the maximum temperature reaches 95.3℃,the maximum leakage current is 180 mA;the thermal effect of current accumulates at the fault point,causing the temperature in the area to rise and water to evaporate.With the reduction of water content,the effect of water evaporation on vegetation impedance gradually increases,resulting in a decrease in leakage current,and ultimately the temperature drops to room temperature,so the vegetation will not spontaneously combust or ignite nearby flammable materials through arcing,indicating that the failure of vegetation-touched single-phase conductor of lowvoltage distribution line will not threaten the safety of fire prevention in the forest area.The special case of phoenixtailed bamboo across the two-phase conductor failure and humulus and ivy across the two-phase conductor failure temperature rise obviously,and accompanied by the phenomenon of discharge,under certain conditions can develop into a phase-to-phase shortcircuit,short-circuit arcing ignition of flammable materials near the point of failure,threatening fire safety in the forest area.The results of the study are of great significance for the prevention of fires on low-voltage distribution lines through forested areas.