Also found in: Dictionary, Acronyms, Wikipedia.


(chemical engineering)
A vessel designed to bring two or more substances into contact.
A heavy-duty relay used to control electric power circuits. Also known as electric contactor.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



an electrical device used for frequent closing and opening (up to 1,500 operations per hour) of power circuits carrying direct or alternating current. Contactors are widely used for remote control of machinery and apparatus in DC and AC installations at voltages up to 500–650 volts and currents up to 600 amperes.

Contactors are classified as unipolar or multipolar, depending on the number of contact pairs connected to the power circuit. A unipolar contactor has one pair of contacts, one of which is fixed and the other is movable. The movable contact is fastened to the armature of an electromagnet (with a sucking coil mounted on the core). When the control current flows through the coil the armature is attracted by the core and the contacts are closed. Contactors are usually equipped with an arc quencher, which interrupts the electric arc that arises upon separation of contacts (interruption of an electric circuit carrying a current). A contactor is closed by pressing a push button provided in the supply circuit of the sucking coil. A distinction is made between closing contactors, whose contacts are normally open, and opening contactors, whose contacts are normally closed.

The sucking coil in a contactor draws a current that is insignificant in comparison with the current in the circuit being switched. Both the sucking coil and the contact system in a contactor may operate on direct current, or both may operate on alternating current. Contactors that have a contact system for alternating current and a sucking coil for direct current also exist. In a number of designs, the contacts are locked in their closed position by a latch. Locking contacts, which are structurally connected to the latch, automatically disconnect the power to the sucking coil when the main contacts are closed. In this case the closed position of the contactor does not depend on whether the power is connected to the sucking coil. To open the main contacts of this type of contactor, a separate opening coil is required. Contactors are capable of performing several million switching operations. Contactors are manufactured as self-contained, independently mounted devices and as built-in devices in magnetic starters and industrial machines and installations.


Babikov, M. A. Elektricheskie apparaty, part 2. Moscow-Leningrad, 1956.
Chunikhin, A. A. Elektricheskie apparaty. Moscow, 1967.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


Any device for repeatedly opening and closing an electric power circuit.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
Cohu develops, manufactures, sells and services semiconductor test and inspection handlers, micro-electro mechanical system (MEMS) test modules, test contactors and thermal sub-systems for semiconductor manufacturers and test subcontractors worldwide.
Pointe Claire, Canada, October 22, 2014 --( Future Electronics, a global leading distributor of electronic components, offers Crydom's DRC3 Series of solid state contactors.
Reset power means that the aircraft has the power load applied, but the power is held at the contactors waiting to be distributed throughout the various systems.
Once your unit receives the replacement contactor, you must ship the failed contactor to Ametek.
Summary: TEHRAN (FNA)- Iranian researchers in collaboration with colleagues at University Teknologi Malaysia (UTM) produced appropriate nano membranes to be used in membrane contactors and analyzed their application in gas separation processes.
The YieldPro contactor employs precious metals at the contact point, which, unlike plating, do not wear off and are partly responsible for the contactor's long operating lifetime.
The 14 x 40 Membrane Contactor utilizes a polypropylene hollow fiber and durable PVC housing.
The patent applies to the treatment of water whereby RO or NF permeate is fed into a membrane contactor, which is used to remove dissolved carbon dioxide from water.
Multitest announced that its new 0.3-mm-pitch Atlas contactor successfully passed a customer production-floor evaluation.