接地故障引起电力电缆轰燃的机理与监测预警系统

Mechanism and Monitoring and Early Warning System of Power Cable Burning Caused by Ground Fault

研究了接地故障引起电力电缆轰燃的机理:接地故障电流长时间流过电缆相屏蔽层,因电流密度过高,使之发热熔融了电缆的绝缘材料,并热分解出可燃性气体,进而被单相接地故障点的电弧点燃所致。分析了电力电缆在接地故障状态下的发热过程,建立了热积累模型,并结合电力电缆安全运行规范,以保证电力电缆的使用寿命为目标确定轻预警值,确保不发生因接地故障发生电力电缆轰燃事故为目标确定重预警值,并建立了1个由300余个监测点组成的10 kV配电网的电力电缆轰燃监测预警系统。

Studying the mechanism of power cable burning caused by ground fault:the grounding fault current flows through the cable phase shield for a long time,and the current density is too high,causing it to heat and melt the cable insulation material,and thermally decompose flammable gas,which is ignited by the arc at the single⁃phase grounding fault point.The heating process of power cables under ground fault conditions was studied and a heat accumulation model was established.Combined with the power cable safe operation specifications,the light warning value was determined with the goal of ensuring the service life of the power cable,and the heavy warning value was determined with the goal of ensuring that the fire accident of the power cable does not occur due to ground faults.A power cable burning monitoring and early warning system for a 10 kV distribution network consisting of more than 300 monitoring points was established.