10 Differences Between A Contactor And A Relay

Today we will talk 10 differences between a contactor and relay. Contactors and relays are two common electrical control devices. Their differences are mainly reflected in appearance, structure, function, application scenarios, etc., as follows:

Table of Contents

1. Appearance difference between a contactor and relay

Contactors are usually larger than relays, and have a structure consisting of an electromagnet and contacts on the outside. The contacts are made of copper alloy, which has high wear resistance and electrical conductivity. The relay is usually smaller than the contactor, and has a structure consisting of an electromagnet and contacts on the outside. The contacts are made of silver alloy, which has good electrical conductivity and low current breaking characteristics.

the differences between a contactor and relay

2. Structure

Contactors and relays are also different in structure. Contactors usually include electromagnets, contacts, connectors, and fixed plates, while relays usually include electromagnets, contacts, moving irons, and fixed plates.

Contactor and relay structure difference

4. Application scenarios

Because the contactor can withstand large current and voltage, it is usually used in high-power, high-load application scenarios, such as motors, resistance furnaces and other equipment in industrial production. Relays are usually used in electronic circuit control, automation equipment control, instrumentation and other fields.

5. Switching voltage and current

Contactors and relays also vary in switching voltage and current. Contactors can usually withstand higher voltages and currents, generally up to thousands of volts and hundreds of amperes, while relays can usually only withstand voltages and currents of tens of volts and tens of amperes.


6. Accuracy and stability

Because the contacts of the contactor are made of copper alloy material, it has good electrical conductivity and wear resistance, making it still have high precision and stability under high load and frequent operation environment. The contacts of the relay are made of silver alloy material. Although its electrical conductivity is better, compared with copper alloy material, its wear resistance and service life are slightly inferior.

7. Noise

Since the contactor is usually used for higher power load control, it will generate a lot of electromagnetic noise when operating. Relays are usually used for low-power load control such as electronic circuit control, and the noise is relatively small.

8. Control method

Contactors and relays are also controlled differently. The contactor usually adopts three control methods: manual, automatic and remote, and can be remotely controlled by buttons, control cabinets, computers, etc. The relay usually adopts electric signal control mode, which can realize automatic control through computer, PLC, etc.

9. Reliability

Contactors and relays also vary in reliability. When the operating frequency and load current of the contactor are high, problems such as poor contact, arcing and electromagnetic interference are prone to occur, which will have a certain impact on the stability and reliability of the equipment. The relay is relatively more stable and reliable because it is used for signal control of small current and low power.

10. Cost

Due to the large load capacity of the contactor, the materials used and the manufacturing process are relatively complicated, so its cost is usually high. The relay is relatively low in cost due to its advantages of miniaturization and stable electrical performance.


To sum up, beside the above part metionded 10 differences between a contactor and relay, there are also different in terms of control methods, reliability, and cost. It is necessary to select suitable equipment according to specific application scenarios and needs in order to achieve the best control effect and cost-effectiveness.

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