ABSTRACT
Surge-protective devices are components used in power and data systems to protect the hardware and, if possible, the function of these systems against damages or disturbances caused by transient overvoltages or overcurrents. This chapter presents an overview of surge protection, starting with the occurrence and nature of surges. It addresses toward power systems; varistor applications in the telecommunications industry will be guided by similar considerations. Therefore, the expectation of performance of surge-protective devices will depend on the point of reference of various users. These low-impedance paths include surge-protective devices as well as the paths established by dielectric breakdown. Lightning surges on power systems occur in two modes: direct attachment of the lightning path to the power system conductors, and electromagnetic coupling of energy into power system conductors by the radiation of a nearby lightning discharge.
