A contactor is essentially similar to a relay, only that it’s used in applications that require much higher current. One of the features that distinguish it from a standard relay is its ability to withstand high currents. Contactors are designed to be either open or closed. In open contactors, the circuit breakers are normally closed to allow for opening when conditions on the circuit become dangerous. This allows for the power to the load to be shut down when the power is cut off. 


Compared to relays, contactors are almost always larger in terms of physical size. That’s why the smallest contactor will be almost the size of a human hand. The largest contactor would typically require heavy equipment to move and install.

Contactors are generally categorized as industrial grade equipment used in circuitry with much higher electric current and voltage than what’s used in most households. As switches, contactors have the ability of being operated remotely. They are usually designed to operate at voltages similar to the loads they control.

Complex machines

A contactor is composed of three parts. Contacts refer its current-bearing parts such as contact springs, power contacts, and auxiliary contacts. The second component is the electromagnet which provides the force to close the contacts. The enclosure, a frame housing the contact and the electromagnet is the third and final component. It is usually made from insulating materials such as Nylon 6, Bakelite, and Thermosetting Plastics. Apart from insulating the contacts, these usually provide a measure of protection from the effects of being touched by some personnel. Some contactors may even have an additional enclosure to protect them from the elements, oil, dust, and explosion hazards.

One of the ways of distinguishing different types of contactors is the type of switching they provide. They can either be referred to us poles or throws just like any other switch. They function by either by changing the state of one particular circuit or that of multiple circuits. Simple as they are, contactors are part of some of the most complex machines in the world.


Contactors find their most basic use in industrial-scale applications such as starting the motor, controlling furnaces, and regulating the speed of very large motors. As electricity flows through the device, it turns on the electromagnet causing it to generate a strong magnetic field. This pulls an iron core into the coil creating an electrical arc. This allows electricity to pass through one contact into the parent device. Deactivating a contactor simply entails removing it from its parent device. Alternatively, disconnecting electric current activates the spring to push the core away from the coil. This breaks the connection.

There are many different types of contactors. If you’re interested, you may check out this website.

Contactors are usually very reliable only when they are used for the right application. Motor contactors should thus be used or only that. Using them for lighting will only mean exposing them to premature malfunctioning. When they transmit too much current, the most likely result in overheating. The voltage that’s too low or too high may also make the coils to overheat.