Study on Fire Initiation of Wire Insulations on Board the Satellite

The damage and overheating of wire insulation is the main ignition source in the fire incidents of the manned spacecraft in microgravity. Anyway, until now the study on wire insulation flammability in microgravity is limited. Thus the study on fire initiation of wire insulation in microgravity is of importance for fire safety in spacecraft. The experimental hardware was developed to perform the experiments of fire initiation of wire insulation caused by overload on board the SJ-8 China recoverable satellite. In the experiments, the fire initiation characteristics including the temperature and radiation characteristics of the wire insulations were presented. The temperature histories of the wire insulation in microgravity and the low-pressure environment in normal-gravity were obtained. Effects of overloaded currents on the fire initiation were investigated for different wire coiled states. The results indicate that the natural convection almost vanished and the heat loss of the electric components decreased in the microgravity environment. It might cause overheat of the electric components and then results in fire, and thus the fire risks of wire in the microgravity condition are much more dangerous than that in normal-gravity under the condition of overload.