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Relay vs. Contactor: Key Differences Explained

relay contactor electrical switch circuit current

This article explores the differences between relays and contactors, two essential electromechanical devices used for switching electrical circuits. Let’s delve into what distinguishes them.

What is a Relay?

A relay is an electrically controlled switch that opens and closes contacts to control other devices within the same or a different electrical circuit.
Relays are typically employed in circuits with lower current capacity, generally up to a maximum of 20A.
They are generally smaller in size compared to contactors.
Relays usually possess at least two normally open (NO) or normally closed (NC) contacts.
Relays find applications in various circuits, including control circuits, automation circuits, protection circuits, and switching circuits.

Relay vs Contactor

What is a Contactor?

A contactor is also a specialized type of relay, specifically designed for switching electrical circuits ON and OFF.
Contactors are used to handle the switching of high currents, potentially up to 12500A.
They often house a set of 3-phase power contacts. Some contactors also include auxiliary contacts for additional functionality.
Arc suppression mechanisms are typically integrated within contactors to handle the arcing that can occur when switching high currents.
Contactors are primarily used in switching applications involving motors, lights, and capacitors that draw substantial currents.

Relay vs. Contactor: Key Differences

The following table highlights the main differences between relays and contactors:

Specifications	Relay	Contactor
Application	Used for lighter load switching (below 5 KW). Light duty switch.	Used for heavier load switching. Heavy duty switch.
Voltage	Used for low voltage applications.	Used for high voltage applications.
Cost	Cheap	Expensive
Repairing	Not economical to repair.	Designed such that it can be repaired.
Main application	Used in control circuit only.	Used in both control circuit as well as power circuit.

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