The effects of an inert central core on the thermal pyrolysis of an electrical cable

Abstract

A mathematical model is formulated to simulate pyrolysis of the insulation layer of an electrical cable. The cable is vertically orientated and the model resembles a cable flammability test similar to IEC 60332-1 (Test on Electrical Cables Under Fire Conditions). Only non-flaming pyrolysis is investigated in this paper. The composition of the cable is idealised such that it consists of an inert central core and an insulation layer. The configuration of the external heat source is also simplified such that only the truncated end of the cable sample receives heat. Pyrolysis is modelled as ablation which assumes a single constant critical pyrolysis temperature. Investigations are concentrated on the effect of the thermal properties of the central core on the pre-heating time and the initial stage of pyrolysis.