The relay and contactor are electromechanical protective devices. These two devices work for the switchgear and protection power system.
Both devices are widely used for the same purpose-
- to perform circuit switching operations during abnormal circuitry conditions
- and to protect the connected device from hazardous situations.
These are the basic roles to perform the circuit switching task. Under the working role and other specifications, these two components can be differentiated.
In this article, we are studying the difference between relay and contactor.
Let’s compare both.
Relay vs Contactor [in Tabular form]
| # | Content | Relay | Contactor |
| 01 | What are the relay and contactor? | A relay is a protection device that operates and controls low-power signals. | A contactor is an overload protection device that operates and controls high-power signals. |
| 02 | Construction | Usually, it is assembled in the control circuit. | It is assembled in the main circuit (i.e. both control and power circuits). |
| 03 | Inbuilt Function | The relay is designed to operate with normally open (NO) contact or normally closed (NC) contact at specific requirements of the system. | The contactor is designed to operate only normally open (NO) contact. |
| 04 | Voltage Capacity | This device is rated for low and medium voltage i.e up to 250V. | This device is rated for high voltage i.e. up to 1000V. |
| 05 | Current Capacity | It has a less current-carrying capacity i.e. below 15A. | It has a more current-carrying capacity i.e. above15A. |
| 06 | Power Consumption | The relay consumes low power. | The contactor consumes more power. |
| 07 | Power Source | This device is suitable for a single-phase AC system. | This device is suitable for a single-phase or three-phase AC system. |
| 08 | Switching Speed | It has a high switching speed. | It has a low switching speed. |
| 09 | Features | This device does not contain additional safety features. | This device contains additional safety features (such as spring-loaded contacts, arc suppression, overload, etc). |
| 10 | Working | It works in the control loop. | It works in the main loop. |
| 11 | Cost | The cost of the relay is low as compared to the contactor. | The cost of the contactor is high as compared to the relay. |
| 12 | Size | The relay finds in a compact size than the contactor. | Usually, the contactor finds in a larger size than the relay. |
| 13 | Uses (or Applications) | It is commonly used in industrial automation (for PLC systems), automobile, and other domestic applications (for example- electric motors, telephones, railway lines, etc). | It is commonly used in commercial and heavy load applications (for example- electrical transformers, induction motors, capacitor banks, etc.) |
These are the basic difference between relay and contactor. This comparison covers the advantages (or pros) and disadvantages (or cons) of both.
If you have any queries or points to add, you can comment below.
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Thanks for Reading!
I have completed master in Electrical Power System. I work and write technical tutorials on the PLC, MATLAB programming, and Electrical on DipsLab.com portal.
Sharing my knowledge on this blog makes me happy. And sometimes I delve in Python programming.
Great post! You explained the difference between relays and contactors in a very clear way.
Thank you 🙂