电线电缆带电燃烧研究进展

The State of the Art of Combustion Behavior of Live Wires and Cables

分析了当前国内外在电线电缆带电燃烧方面的研究进展,主要关注了在役电缆温升特性、带电电缆故障着火机理和电流变量与燃烧特性的相互影响,分别对应了带电电线电缆起火本质原因、引燃特性及火焰蔓延特性。在电缆温升特性方面,分析了以热路模型或者数值计算模型为基础所建立的各类电缆线芯温度预测模型,并介绍了基于电缆温度预测模型所建立的各类线缆温度监测系统。在带电电缆故障着火机理方面,分析了由于绝缘层表面导电路径、高温导致空气电离及绝缘材料热解而形成的电弧故障引发火灾,以及由于短路、过载和接触不良等导致电缆线芯过热引发火灾的机理,并揭示了不同故障之间的相互诱发关系,分析了多种故障综合作用引发火灾的机理。在带电电缆燃烧特性方面,分析了电场与燃烧的相互影响关系与机理,并揭示了外部引燃条件下,通电电流变量对电缆燃烧特性及蔓延速度的影响规律,分析表明在制定电缆安全的相关标准和规范时,需考虑电缆火灾中持续通电电流的影响。

The state of art on combustion characteristics of live wires and cables are elaborated in this article.The main focus was put on the temperature rise characterictics of inservice wires and cables,the failure-induced fire of live wires and cables,and the mutual influence between current variable and combustion characteristics,which correspond to the nature,ignition characteristic and flame spread characteristic of wires and cables,respectively.In the section of temperature rise characteristics of inservice wires and cables,the prediction models on core temperature based upon thermal circuit and numerical computational models,as well as the core temperature monitoring systems of cables,are presented.In the section of failure induced fire of live wires and cables,two essential failures are discussed.The arc fault due to conductive path formed in the insulating layer and ionized air under external heat is analyzed first.Except for the arc fault,core overheating is another failure that could induce electric fires,which is mainly caused by short circuit,over load and poor connection.The combining effects among different electric faults are also considered.In the section of mutual infulence between current variable and combustion characteristics,we discuss the relationship between electric field and combustion characteristics,and reveal the influences of current variable on combustion and flame spread characteristics of wires and cables under external ignition source.It can be suggested that the influence of current variable on live wire and cable fire should be taken into account when enact the electric safety standards.