Magnets and vacuum-the perfect match [MV distribution switchgear]

There are four main types of circuit breaker in use today for medium voltage distribution system applications: air; oil; SF₆; and vacuum. The first two are rarely manufactured nowadays in the West following the success of SF₆ and more recently the dominance in the medium voltage sector of vacuum. However there are still a significant number of these breakers in use. Typical mechanisms used to drive the circuit interrupter mechanism have been manufactured using pneumatic, hydraulic, springs, solenoids and now permanent magnetic actuator technologies. Pneumatic and hydraulic are considered expensive for the distribution market. They lend themselves more to the transmission sector circuit breakers where mechanical drive linkages become very large and cumbersome. It is far more efficient to use pressure pipes that can be directed in universal directions without the need for special mechanical couplings. This paper describes the ideal matching of the permanent magnet actuator mechanism with the characteristics required to operate successfully, reliably and efficiently a vacuum interrupter type switch