Vacuum Contactor Switches
Vacuum contactors utilize vacuum interrupter encapsulated contacts to suppress the arc. Such arc suppression allows the contacts to be much smaller and use less space than air-break contacts at higher currents. As the contacts are encapsulated, vacuum contactors are used extensively in rugged environments such as mining. Vacuum contactors are also widely used at medium voltages from 1000-12000 volts, effectively displacing oil-filled circuit breakers in many applications. Vacuum contactors are usually applicable for use in AC systems. The AC arc generated upon opening of the contacts will self-extinguish at the zero-crossing of the current waveform, with the vacuum preventing a re-strike of the arc across the open contacts. Vacuum contactors are therefore very efficient at disrupting the energy of an electric arc and are used when relatively fast switching is required, as the maximum break time is determined by the periodicity of the AC waveform.