It is used in control circuits.   

The contactor is a switch in the condensing unit that receives a signal from the thermostat to turn the compressor and fan motor on & off.

A two-state (On-Off) device for repeatedly establishing an interrupting an electric power circuit. Interruption is obtained by introducing a gap or a very large impedance.

An electric relay switch.

An electromagnetic actuated relay. Usually used to refer to the relay which closes the circuit to a compressor.

A switch that can repeatedly cycle, making and breaking an electrical circuit. When ample current flows through the A-coil which is built into the contactor, the resulting magnetic field causes the co [..]

An electromagnetic actuated relay. Usually used to refer to the relay which closes the circuit to a compressor.

A contactor is an electrically operated switch usually used in control circuits and whose contacts are considered high amperage, compared to a relay.

A switch that can repeatedly cycle, making and breaking an electrical circuit. When sufficient current flows through the A-coil built into the contactor, the resulting magnetic field causes the contac [..]

A switch that can repeatedly cycle, making and breaking an electrical circuit. When ample current flows through the A-coil which is built into the contactor, the resulting magnetic field causes the co [..]

A device used to energize and de-energize an electric power circuit.

an electromagnetic actuated relay. Usually used to refer to the relay, which closes the circuit to a compressor.

A contactor is an electromechanical device used to open and close an electrical power circuit.

An alarm unit used in cable pressurization schemes which activates when there is a fall in pressure. Also a large mechanical relay used to open or close electrical circui [..]

A switch that can repeatedly cycle, making and breaking an electrical circuit. When ample current flows through the A-coil which is built into the contactor, the resulting magnetic field causes the co [..]

A switch that can repeatedly cycle, making and breaking an electrical circuit. When sufficient current flows through the A-coil built into the contactor, the resulting magnetic field causes the contac [..]

A switch that can repeatedly cycle, making and breaking an electrical circuit. When ample current flows through the A-coil which is built into the contactor, the resulting magnetic field causes the contacts to be pulled in or closed.

A switch that can repeatedly cycle, making and breaking an electrical circuit. When ample current flows through the A-coil which is built into the contactor, the resulting magnetic field causes the contacts to be pulled in or closed.

A switch that can repeatedly cycle, making and breaking an electrical circuit. When ample current flows through the A-coil which is built into the contactor, the resulting magnetic field causes the co [..]

A switch that can repeatedly cycle, making and breaking an electrical circuit. When sufficient current flows through the A-coil built into the contactor, the resulting magnetic field causes the contacts to be pulled in or closed.

An electric switch, usually magnetically operated.

A switch that can repeatedly cycle, making and breaking an electrical circuit. When sufficient current flows through a coil built into the contactor, the resulting magnetic field causes the contacts to be pulled in.

An electromagnetic actuated relay. Usually used to refer to the relay which closes the circuit to a compressor.

This is the gateway for the outdoor unit to receive high voltage.  Low voltage is sent from the air handler after it has gotten the signal from the thermostat to turn on and cool.  Once the low voltag [..]

A switch that can repeatedly cycle, making and breaking an electrical circuit. When ample current flows through the A-coil which is built into the contactor, the resulting magnetic field causes the co [..]

A switch that can repeatedly cycle, making and breaking an electrical circuit. When ample current flows through the A-coil which is built into the contactor, the resulting magnetic field causes the co [..]

A switch that can repeatedly cycle, making and breaking an electrical circuit. When ample current flows through the A-coil which is built into the contactor, the resulting magnetic field causes the co [..]

An electro-magnetic device for opening and closing an electric power circuit.

An electro-mechanical device that is operated by an electric coil and allows automatic or remote operation to repeatedly establish or interrupt an electrical power circuit. A contactor provides no overload protection as required for motor loads.