Differences Between Intermediate Relay and Contactor

1. Core Distinction in One Sentence

Intermediate Relay: Transmit signals, carry low current, serve as signal transfer station

Contactor: Drive loads, carry high current, control motors

2. Intuitive Comparison
3. Current Carrying Capacity

Intermediate Relay: Max 6~10A, only for low current circuits

Contactor: 10A up to thousands of amperes, applicable to high-power equipment

2. Main Application

Intermediate Relay: PLC signal conversion, multi-circuit wiring, circuit interlocking, contact expansion

Contactor: Directly control high-power loads such as motors, water pumps, fans and heating tubes

3. Contact Difference

Intermediate Relay: Equipped with only small contacts without main/auxiliary distinction, large quantity of contacts

Contactor: Composed of high-current main contacts and low-current auxiliary contacts; main contacts are specially designed for load current transmission

4. Arc Extinguishing Performance

Intermediate Relay: Without arc shield, incapable of breaking strong electric arc

Contactor: Built-in arc shield to extinguish electric arc during power-off and prevent contact burnout

5. Size & Price

Intermediate Relay: Compact and low-cost, densely installed in control cabinets

Contactor: Larger in size and higher in price

6. Coil Working Principle

They share the same working principle: Low-current coil pulls in to control contact on-off.

The only difference lies in the maximum current bearing capacity of contacts.

3. Practical Selection Rules

Use intermediate relays for weak current signal conversion

Use contactors for start-stop control of high-power motors

Add intermediate relays to expand contacts when auxiliary contacts of contactors are insufficient

4. Typical Application Scenarios

Low signal switching inside control cabinets: RXM series intermediate relays

Start-stop control of 380V motors: AC contactors are mandatory