Vacuum Switchgear Application Study with Reference to Switching Surge Protection

The unique characteristics of, vacuum circuit breakers have raised the issue of whether special criteria should be developed relating to their application on medium-voltage power systems. A computer program is described which models vacuum switching surge phenomena and the measurements required to obtain the vacuum interrupter inputs to the program. The program has been validated by good correlation between computed and measured results relative to a single-phase laboratory circuit and a three-phase unloaded transformer circuit. Examples of the use of the computer program in switching transformer and motor circuits are presented.