Characteristics of faults on aircraft electric systems

THE protection of electric systems has been applied mainly to the prevention of damage to electric equipment caused by overheating or overstressing the components. Normal industrial installations result in systems that, in protecting the specific equipment for which they were designed, also give adequate protection to the surrounding equipment. Unfortunately, it has been assumed, without serious reservation, that similar protective systems for aircraft equipment could perform the same function. In reality, however, the environmental conditions in aircraft operation are much more severe - that is, the structure of the aircraft is much more vulnerable to arc damage - requiring that more extensive and efficient protection be used in the future. It would be rather pointless to install a system that assured the operation of specific equipment if, at the same time, it allowed the structure of the aircraft to be destroyed. Such a contingency can occur under the present philosophy of protection of aircraft electric systems.