A contactor and a relay are both types of electrically operated switches that can control and switch loads.
However, they have some differences in their construction, operation, and applications.
Here are some of the main differences between them:- A contactor is designed for switching high-voltage and high-current loads, such as motors, capacitors, lights, reactors, etc.
A relay is suitable for switching low-voltage and low-current loads, such as control circuits, small electronic devices, etc¹².
– A contactor usually has only normally open (NO) contacts, which means that the circuit is closed when the contactor is energized.
A relay can have both normally open (NO) and normally closed (NC) contacts, which means that the circuit can be either closed or opened when the relay is energized².
– A contactor often has additional auxiliary contacts that are activated along with the main contacts.
These auxiliary contacts can be used for performing additional functions related to the control of the contactor, such as turning on a pilot light or interlocking with another contactor¹².
– A contactor has some safety features to prevent or reduce the effects of arcing, which is the formation of an electric discharge between the contacts when they are opened or closed.
These features include spring-loaded contacts, which ensure that the contacts are separated quickly and evenly, and arc suppression devices, which extend the path of the arc and reduce its intensity².
– A contactor is typically used in three-phase applications, where it can switch all three phases simultaneously. A relay is more commonly used in single-phase applications, where it can switch one or two poles²⁴.