What Is The Difference Between Relays And Contactors?

by Sebastian

If you have dealt with electric circuits at any point, you certainly have the head of the terms relay and contactor or contactor relay. Both relays and contactors are electric gadgets, and their functions are almost similar. For this reason, contactors are often mistaken for relays and vice versa. This article explains the contrasts between the two electric devices.

How are contactors different from relays?

Defining the two devices may not be enough to create an adequate distinction between them. Below are further distinctions based on operation and physical elements;

1. Loan Capacity

The main difference between the two is their load capacity. Relays only have a load capacity of 10A or less. On the other hand, contactors have a load capacity that surpasses 10A easily. \

2. Contact standards

Contactors are solely intended to work with regular open, which is known as form A contacts. On the other hand, in relays, the way they open or close is significantly dependent on the desired application. This implies that with a contactor when it is not energized, there is no connection entirely while in a relay, there could be some connection.   

Another significant difference is that contactors are regularly fitted with helper contacts. The contacts can either be NO or NC. The secondary contacts are utilized to play out extra capacities related to the control of the contactor. For instance, the contactor may transmit capacity to the engine, while the helper contact is in the control circuit of the engine starter and ordinarily used to turn on a pilot light showing the engine is working.

3. Safety

The safety features differ from one type of contact to another. Some common safety features include;

· In spring-loaded contacts

Since contactors are regularly conveying high loads, they frequently contain safety features. Spring-loaded contacts help guarantee the circuit is broken when the device is non-excited. This feature comes in handy in situations where the contacts are likely to weld themselves together.

· Arc Suppression

Another wellbeing element generally that is included in contactors is arc suppression. The main reason it is included is because of the high loads they ordinarily convey. The feature works by a magnet. Magnetic arc suppression works by broadening the way a circular segment would need to travel. In the event that this separation is broadened further than the energy can survive, the arc is suppressed. Since ordinary relays aren’t intended for high loads, arcing is, to a lesser degree, a worry hence the reason why they don’t feature arc suppression elements.

· Overloads

Contactors are ordinarily associated with overloads that tend to interrupt on the circuit if the current surpasses a set edge for a chosen timespan, typically 10-30seconds. This is to help ensure the gear downstream of the contactor from harm because of the current. Over-burdens are considerably less regular on relays; hence they do not feature overload elements.


Contactors and relays are constructed similarly. They both have an outer envelope to shield all the inward parts from the environmental conditions. An electromagnetic coil is used for opening and shutting of contacts. The contacts are opened and shut when this electromagnetic coil is energized.

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