ABSTRACT
Switching surges occur on power systems as a result of instantaneous changes in the electrical configuration of the system, and such changes are mainly associated with switching operations and fault events. Possible switching surge magnitudes are indicated, and operations and areas of interest that might warrant investigation when applying such equipment are discussed. Surges associated with switching transmission lines include those that are generated by line energizing, reclosing, fault initiation, line dropping, and fault clearing. Single phase switching as well as three phase switching operations may also need to be considered. Switching surge overvoltage produced by line switching are statistical in nature—that is, due to the way that circuit breaker poles randomly close, the instant of electrical closing may occur at the crest of the system voltage, at voltage zero, or somewhere in between. The occurrence of a fault on a transmission line also can result in switching surge type overvoltage, especially on parallel lines.
