A vacuum circuit breaker comprises an interrupter for each phase of a three phase electrical system. Each interrupter includes a cylindrical housing for containing circuit breaker contacts. The axes of the housings are vertically disposed and are arranged to define an equilateral triangle. Projecting...http://www.google.es/patents/US4587390?utm_source=gb-gplus-sharePatente US4587390 - Vacuum circuit breaker
