Surviving a strike

A lightning strike is not a pleasant experience under any circumstances. For electrical equipment it is not just the voltage peak that can cause damage, but also the sudden and rapid voltage rise. In some cases the voltage transients are far steeper than those that occur in typical situations covered by common standards – they can surge by megavolts in the space of microseconds. The insulation covering the windings of transformers and motors is not normally designed for such transients and can suffer permanent damage if no additional protection is used. Studies show that despite each piece of equipment being designed to withstand typical surges, as many as 35 percent of total dielectric failures in power equipment may be caused by such surges [1]. One solution is to totally redesign equipment to better cope with such transients. A simpler approach involves adding a component that protects the equipment from surges without affecting normal everyday operation.