Engineer's Asylum

3-phase relay connection

How can I connect a 3-phase relay to motor and Arduino for operating motor with Mobile which is in fields?

Give more details! What’s the operating voltage and power of the motor?

5/7HP, 440volts water pump

First of all, I am not an expert in high power electrical system. So I had to borrow the solution suggested by GeraGueb in our Telegram Group.

According to him, you have to use a magnetic contactor to do the job.


You have to connect the three-phase motor circuit breaker before the contactor. The three phases line goes to 3 phases breaker just as shown in the below image. The image is for 2 phases but the same method applies for 3 phases as well.

The A1 of the contractor goes to Arduino pin and A2 goes to the board’s ground.