Recently one of my YouTube channel subscribers asked an interesting question. He asked me that how he can connect a 3-phase motor protection circuit breaker (MPCB) to a single-phase motor?
Can we do that, is that possible?
Yes, but with word of caution.
Caution!
Be sure to use the correct type of breaker for the electrical circuit. Read the manufacturer’s guidelines before doing such connections. If in their manual/catalog, they mention such connections then only you can do otherwise not. Like Schneider GV2 and GV3 allows you to connect single-phase load as mentioned on their official website.
Unless do not try to do the connections without knowing the internal circuit of the circuit breaker.
Check out this video to understand and see the inside view of the circuit breaker.
Here. I will give you step by step guide to connect 3 phase MPCB to a single-phase motor.
How to connect 3-phase motor protection circuit breaker to single phase motor?
Step 1: First connect the live wire to L1. Look at the below image.
Step 2: Then connect the neutral wire to L3.
Step 3: Now connect the motor wires to the T1 and T2 terminals of MPCB.
Step 4: Finally, connect a wire from L2 to T3 of MPCB.
Explanation
In a single-phase circuit, neutral acts as a return path.
You know that – right?
So, we must do a connection such that all three poles of the motor protection circuit breaker come under the loop.
Take a look at the below image. The two poles of the motor protection circuit breaker are in series.
In this way, you can run a single-phase motor with 3-phase MPCB.
Make sure that now you adjust the range of MPCB as per motor nameplate current ratings.
So if wiring a motor with a timer circuit.
Motor connects to MPCB as your diagram.
Power to MPCB comes from contactor, neutral goes from MPCB back to contactor..
This circuit is for ON / OFF purpose only.
For connecting timer circuit as well as contactor, you may need to rethink and design the circuit.
Good