Hus Rupani:
Hi, I’m Hus. In this video, I will connect the split phase motor using our Motor Faults Pracbox. Let’s get started.

So in this circuit, we’ll have a 41.5 volt power supply, which will connect right across our main winding. And across the main winding, we’ll have our auxiliary winding and a power resistor, which will, in combination, be our simulated start winding for the split phase motor. We’ll then connect that in series with a toggle switch, which will be our simulated centrifugal switch or a start relay. Let’s connect this circuit on the Motor Faults Pracbox, and we’ll cross off the wires as we connect it.

Here we have our Motor Fault Pracbox, and this is our single phase induction motor. These are all the components that we have to connect in this circuit, but we’ll only connect our main winding auxiliary winding power resistor and our toggle switch. On this side, I have our distrobox, which is coming from the porter phase to give us the 41.5 volts that will run our single phase induction motor.

First, we will connect our power supply to the main winding. Then we’ll connect the neutral to the main winding. Before we proceed in connecting our circuit further, let’s turn the power supply on and see what it does. Since it’s only got the main winding in the circuit, it doesn’t have any starting circuit. If I then flick the shaft, you can see how the motor starts to spin, and if I stall it and then flick it in the reverse, then the motor starts turning as well. Now we will add the start circuit or the starting circuit to the main winding.

Now we will wire the active to the auxiliary winding, then the auxiliary winding to the power resistor, and the power resistor to the simulated centrifugal switch. So active to the auxiliary winding, auxiliary winding to the power resistor, and power resistor to our simulated centrifugal switch. Now what we have here, auxiliary winding and the power resistor in combination, they create a simulated start winding. As you can appreciate, the resistor isn’t a real component inside a motor, but what it’s giving us here is a phase shift between the main winding and the auxiliary winding when they are in combination. The start winding, as you know, for a split phase motor, will have a higher resistance than the main winding, and that’s what we’re trying to simulate here. The centrifugal switch or this toggle switch is going to be in the on position when we start the motor, and then we’ll see, step by step, how the motor will respond to the speed of the shaft. Finally, we’ll connect our neutral to the main winding neutral, which will then go back to the power supply.

So let’s connect that. Okay, now our circuit is complete. Let’s turn it on and see what happens. If you remember when I had just connected the main winding, it wasn’t turning the shaft. I had to physically turn it, but this time, we have a starting circuit, which means the motor shaft should turn on its own. Let’s take a look. If I turn that on, we can see that the motor shaft starts spinning. If we look at this whole process step by step, we will say that soon as the motor starts, the centrifugal switch is in on position. Once the speed reaches 75% of its rated speed, the centrifugal switch will turn off or the start relay will turn off, and the motor will continue to spin. At this stage, with this centrifugal switch disconnected, we only have the main winding in the circuit, not the rest of the starting circuit.

However, if the load on the shaft increases and the motor goes below the speed that the starting circuit needs to kick in, that’s when the starting circuit will kick back in, and it will start turning the shaft. Once it reaches the 75%, it will disconnect again, and it will keep going.

As you can appreciate, the phase shift between the main winding and the start winding isn’t a lot, because it’s only a resistive circuit here, and that’s an inductive circuit, so it’s only got higher resistance. It’s got a very small phase shift. Theoretically, I think the phase shift is about 30 degrees. Of course, this can be improved if we were to put a start capacitor in this circuit, but that’s a topic for another video.

As you can appreciate, the split phase motor isn’t designed for a high starting or running torque. That’s what the cap-start, cap-run-type motors are designed for, but it is good enough for a certain type of applications.

I hope you enjoyed this video. If you have any questions or feedback, please feel free to contact us. Thank you for watching.