ABSTRACT
Switching surges occur on power systems as a result of instantaneous changes in the electrical con-šguration of the system, and such changes are mainly associated with switching operations and fault events. ese overvoltages generally have crest magnitudes which range from about 1 to 3 pu for phaseto-ground surges and from about 2 to 4 pu for phase-to-phase surges (in pu on the phase to ground crest voltage base) with higher values sometimes encountered as a result of a system resonant condition. Waveshapes vary considerably with rise times ranging from 50 μs to thousands of μs and times to halfvalue in the range of hundreds of μs to thousands of μs. For insulation testing purposes, a waveshape having a time to crest of 250 μs with a time to half-value of 2000 μs is o¶en used.
