The Motor Starter Pracbox will let you do DC injection braking with this DC power supply and the three-phase motor. To do that demonstration, we’ll use the contactor, the output from the VSD, through that contactor do a direct online and then connect the motor. And then I will use this push button to route the DC supply through it. Now, normally you’ll need a timer and another contactor. So if you already have our control circuit Pracbox, you can use both of them together and control the braking circuit that way. Let’s connect the DOL circuit first.

Okay, that’s our DOL circuit. Let’s see if it works. That, and stop. What I’d like you to notice is how long it takes for this motor to turn off. So with this flywheel, as I said, visualization will be quite easy. So let’s turn it on, full speed. If I stop it, you can see how it takes a few revolutions before it comes to a complete stop. So what we’ll do now, we’ll use this DC supply. We’ll connect the terminals across the red and blue phases, so U and W phases, and we’ll route it through this push button’s normally open terminal. That way when I press this, it will allow the DC to go through it.

However, the reason you would need another contactor for a proper circuit is because you want the AC to be disconnected completely before the DC comes in. So for that, what I’ll do, I will start the motor, stop the motor, and as soon as I’ve stopped it, I know that the circuit is disconnected. Then I’ll press the push button to see how quickly the flywheel stops. So let me connect that circuit. All right, now my circuit’s ready. First, we’ll operate it normally without the brake, takes a few revolutions to stop. Let’s do that again, but this time we’ll press the brake, after we press stop. You can see how the motor stopped almost instantly. Let’s do that again. So that’s our DC injection braking.

Now that we’ve looked at the demonstration for braking, let’s now talk about the safety aspects of the Motor Starter Pracbox. The first thing for electrical safety is the voltage. So in this case, on the panel, all we have access to is extra low voltage. So the output from the VSD is ELV, the contactor is ELV, the soft starter is ELV, and the motor itself is also extra low voltage. The second safety consideration is the mechanical safety because we have a motor here. We’re using a safe torque motor, which is quite low in torque. So when we wire it up, you can see how the flywheel is exposed. Students will be able to touch it without any problem. And the reason we kept it that way so they can stall it if they wanted to. Let me wire it up and show you how that works.

Okay, I am going to turn the motor on now, and now I’m going to try and stall it. You can see how I can stall the motor with no problem. And the third aspect is circuit protection. As you can see, every line from the VSD output has a fuse, DC supply has a fuse, and the AC supply will also have a fuse, so that way if the students create a short circuit, the circuit protection will kick in. The DC power supply also has a short circuit and overcurrent protection built in. So if anything happens, that safety will also kick in.

Now that we’ve talked about the safety aspects that we’ve put in the Motor Starter Pracbox, let’s now talk about the upcoming changes because this still is a prototype. After some feedback and discussion, we found that there are some changes that we’ll have to make. The first and the most obvious one is the three-phase motor terminal. We’re using six terminals at the moment, but what we’ve found with research is when people are using VSDs or soft starters, they only need three terminals and they want a Delta connected motor. So we’re going to replace this with a three terminal and do the Delta connection internally. That way we can save some space and you will need three less wires. The second change that’s coming up is the DC and AC supply. So this DC power supply will move from here and put it around this area. We’ll also include a toggle switch. So in case you don’t want to use this push button, you can just use the toggle switch to turn it on and off.

We’ll also add a separate AC supply terminals here, which will also be taken from the VSD output. So rather than piggybacking from one of these terminals as I was doing when I was doing the demonstration, you’ll be able to use it separately. So for the contactor operation or the soft starter operation, you’ll be able to use the 24 volt AC. And the third change that we’re considering is we’ll replace this push button with a selector switch because some of the macros on ABB requires a selector switch. For example, doing forward or reverse or hand auto, I think selector switch will be much better control rather than a push button. We’ll also add a pilot lamp because some of the digital outputs using macros, they need a lamp to show the motor is operational. And that’s all the changes we’re planning to make in the final version of the Motor Starter Pracbox. I hope you enjoyed the demonstration of our new product Motor Starter Pracbox with VSD and Soft Starter. If you have any questions or feedback, please feel free to contact us. Thanks for watching.