A busbar stability test evaluates the ability of busbars to remain mechanically and thermally stable under normal operating conditions and during short-circuit events. Busbars are the backbone of power distribution systems in substations, switchgear, and industrial plants. Special service conditions, for example in ships and in rail vehicles provided that the other relevant specific requirements are complied with. Electrical equipment of. Differential protection provides high speed fault-clearing necessary for critical busbars such as transmission busbars, or distribution busbars where arc flash hazards are a concern. Two different types of high-voltage busbars, consisting of a polyamide 12 and a glass-fiber-reinforced (30%) polyamide 6.