Contactor
From Wikipedia, the free encyclopedia
AC contactor for pump application.
In semiconductor testing, contactor can also refer to the specialised socket that connects the device under test.
In process industries a contactor is a vessel where two streams interact, for example, air and liquid. See Gas-liquid contactor.
A contactor is an electrically controlled switch used for switching an electrical power circuit, similar to a relay except with higher current ratings.[1] A contactor is controlled by a circuit which has a much lower power level than the switched circuit.
Contactors come in many forms with varying capacities and features. Unlike a circuit breaker, a contactor is not intended to interrupt a short circuit current. Contactors range from those having a breaking current of several amperes to thousands of amperes and 24 V DC to many kilovolts. The physical size of
contactors ranges from a device small enough to pick up with one hand, to large devices approximately a meter on a side.
Contactors are used to control electric motors, lighting, heating, capacitor banks, thermal evaporators, and other electrical loads.
Contents [hide]
? 1Construction ? 2Operating principle ? 3Arc suppression ? 4Ratings
o 4.1IEC utilization categories o 4.2NEMA
? 5Applications
o 5.1Lighting control o 5.2Magnetic starter o 5.3Vacuum contactor ? 6References
Construction[edit]
Albright SPST DC contactor,
sometimes used in Electric vehicle (EV) conversions
Powerful DC contactor with electro-pneumatic drive
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A magnetic starter is a device designed to provide power to electric motors. It includes a contactor as an essential component, while also providing power-cutoff, under-voltage, and overload protection.
Vacuum contactor[edit]
Vacuum contactors utilize vacuum bottle encapsulated contacts to suppress the arc. This 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 fairly extensively in dirty applications, such as mining.
Vacuum contactors are only 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.