Lightning and Surge Protection

Surge voltages are a significant hazard in power transmission and distribution systems. Surges are the causes of much equipment failure, such as downed conductors, fires, and step and touch potentials, which may injure people nearby. The design manufacture and installation of electrical power equipment and systems must be fundamentally based on safety both for users of the equipment and for those who operate and maintain it. Opening of circuit breakers on capacitors may produce overvoltages resulting in restrike. The restrike is caused by the voltage across the opening contacts to exceed the breakdown voltage of the gap. The resulting transient can reach three times the peak voltage. The temporary overvoltage (TOV) rating should be greater than or equal to the maximum line-to-ground voltage during a single-line to ground fault (SLGF).