Vacuum interrupters: the new technology for switching and protecting distribution circuits

This paper provides application guidelines for, and shows the advantages of, applying vacuum interrupters (VIs) to switch and to protect power distribution circuits. The performance of VIs for load switching and for short-circuit interruption is discussed with reference to long-term switching life and low maintenance costs. During this discussion, the unique ability of the VI to handle developing faults is analyzed. The effects of current chop and voltage escalation on the components in a distribution circuit are examined, and straightforward methods to minimize their effects are presented. The advantages of using VIs for long life, maintenance-free performance for capacitor switching, and for motor switching are discussed. The paper discusses the very fast recovery characteristics of VIs and shows how these characteristics can be used to produce a circuit breaker that will reliably protect distribution transformers. Finally, the use of VIs for other switching duties is examined.