Insulation Failure Mechanism of Cable in Fire Environment

In order to reveal the insulation failure mechanism of the cable under the fire condition, the conductive mechanism and aging mechanism of the cable insulation material were analyzed theoretically, and the relationship between the thermal decomposition weight loss curve and the insulation resistance and temperature of the cable insulation material was constructed. The results show that the reason for the failure of the cable in the fire is that the insulation performance of the insulating material decreases after heating. For different thermal aging degree of the cable, the decomposition process of insulating materials are divided into two stages. When the failure occurs, the insulating material is not decomposed; when the breakdown occurs, the insulating material is in the first stage of thermal loss. Therefore, the failure temperature of the cable can be considered mainly depends on the characteristics of its insulating material, regardless of the structure, shape and size of the cable.