A contactor is a special type of relay used for switching an electrical circuit on or off. They are most commonly used with electric motors and lighting applications. A contactor is an electrically-controlled switch used for switching an electrical power circuit. A contactor is typically controlled by a circuit which has a much lower power level than the switched circuit, such as a 24-volt coil electromagnet controlling a 230-volt motor switch. Contacts perform the current carrying function in a contactor. There are different types of contacts in a contactor, and they are; auxiliary contact, power contact, and contact spring. The power contact has two types that are; stationary and movable contact. A contactor really has only two basic parts: the contacts and the coil. The coil energizes the contactor, moving the contacts into position. The contacts transmit the current from the source to the load.
Each of them has their own individual role to play. Electromagnet: This is the most vital component of a contactor. It provides the driving force that is required to close the contacts of the contactor. Enclosure: The enclosure provides insulation and protection from personnel touching the contacts. The contactor on your AC unit is like a switch located in the AC system’s outdoor condenser unit. It provides power to components such as the compressor and condenser fan and turns the AC unit on and off. Contactors can fail electrically or mechanically. Three-phase, 480 volt AC power comes into the three normally-open contacts at the top of the contactor via screw terminals labeled “L1,” “L2,” and “L3” (The “L2” terminal is hidden behind a square-shaped “snubber” circuit connected across the contactor’s coil terminals).
We use a contactor to turn on and off heavy and high voltage electrical devices such as motors, fans, pumps, etc. – The reason that we use a contactor is to control these heavy high voltage electrical devices indirectly and safely via a PLC and not to connect the PLC directly to these output devices. DC and AC contactors operate on different principles. DC contactors use a magnetic field generated by the coil to move the contacts, while AC contactors rely on the magnetic field created by the alternating current to move the contacts. A contactor is an electrically operated switch which is designed to make or break the electrical power circuits.
