Husnen Rupani:

Hi, I’m Hus. In this video, I want to introduce you to our brand-new equipment called the Transformer’s Pracbox. It’s designed to cover most of the practical components of the transformer’s unit of competency. Let me walk you through the components of this equipment.

So here is our transformers practice. I’ll start from the top left corner. We have one EI Core transformer, we have some power resistors, we have another EI Core transformer. In the middle column, we have a power supply, power meter and a multimeter. And in this final column we’ve got a variac and two toroidal transformers.

The two EI Core Transformers here are exactly the same, 240 volts on the input and 24 volts on the output. That’s the rating of it, so about 10 to one ratio. You can put any input on the primary and you will expect the step-down voltage on the secondary side.

The three resistors that we’ve used here are mainly designed to give you a load on the transformers, so you’ll be able to calculate the voltage regulation of the transformer’s output.

In the middle column, as I mentioned here, we’ve got a power supply, which is a fixed 25 volts, one amp max, and that’s just basically a fixed value voltage, but you’ll be able to make it variable using the variac, and I’ll show you that in a demo.

This unit here is a power meter, which shows you power, voltage, current, power factor, frequency, and energy all in one unit. It’s a very powerful unit. This one here is a multimeter, which is powered internally, and the ammeter fuses have been pulled onto the panel.  If the students blow the fuses, they will be able to replace the fuses themselves.

In the third column, first we have a variac, which is mainly there so you can have a variable output from the power supply, and you can then use it for a short-circuit test and any sort of variable output exercises.

The toroidal transformer here is a single input on the primary and two outputs on the secondary. And this toroidal transformer has two inputs on the primary or two windings on the primary and two windings on the secondary.

You will be able to train students in various combinations of whether you want to make a series on the output or parallel, or if you want to do parallel on the input or the primary and parallel or series on the output. So that gives you a variety of ratios to play with.

Let me show you some demos to show you how the transformer prep box works. In this demo, I want to show you a step-down transformer. We’ll use the EI Core as our step-down transformer. Let’s have a look at the circuit that we’ll connect.

We will connect this circuit where we’ll use power supply, the power meter, EI Core transformer, and the voltmeter to see this whole setup in action. Let’s connect the circuit. Power supply connects to the input of power meter. The output of the power meter connects to the primary of the EI Core transformer. Let’s use this EI Core transformer.

The secondary winding of the EI Core transformer will go to the voltmeter. Let’s set up the voltmeter to the AC setting. Okay, so if we turn this on, our input shows 31 volts, and our output is showing 3.43 volts. You can see that’s roughly 10 to one ratio, slightly higher on the output, and that could be because the transformer output is not loaded.

In this demo, we’ll connect the toroidal transformer as a step-down transformer. Let’s have a look at the circuits that we’ll connect. So first, we’ll connect this circuit where you can see that you have a power supply power meter, and the toroidal transformer that we’ll connect will only connect one of the windings on the secondary to the output.

Then we’ll change this circuit to look like this, where we’ll still have the power supply power meter, but we’ll connect the secondary windings in series and see what that does to the output voltage. Let’s connect the circuit.

We’ll connect the power supply to the power meter. Now I’ll connect the output of the power meter to this toroidal transformer’s primary winding. Now the S1, so one of the windings on the secondary, will connect that to the voltmeter first. And let’s see what output that gives us.

If I turn that on, I have 31 volts on the input or on the primary and on the secondary S1, we have 8.8 volts. Let’s now change the configuration of the secondary of this toroidal to turn this into series winding and see what it does to our output.

Turn the power off first, move our voltmeter connection to S2 and create a short-circuit between the winding S1 and S1. What this has done is made our secondary windings in series. Let’s turn that on and see what it does to our output.

As you can see, the output is doubled. That’s because you’ve got two windings on the secondary giving you the same outputs, and we’ve connected them in series. Our input or the primary is still the same, 31 volts and our output or the secondary voltage has gone up from 8.3 to 16.9.

In this demo, we’ll do a short-circuit test on one of the toroidal transformers. Let’s have a look at the circuit that we’ll connect. In this circuit we’ll have a power supply connected to a variac. And from the variac, we’ll go to our power meter.

From the power meter, we’ll go to one of the primary windings of the toroidal transformer, and the output will be connected to one of the sec. And the output, which is one of the secondary windings will connect straight to an ammeter. So that will allow us to do the short-circuit test. Let’s connect the circuit.

First, we’ll connect our power supply to the variac and the output of the variac to the power meter and see how that changes the voltage. The input terminals of the variac are one and two, and the output terminals are one and three. Let’s see what sort of voltage we get out of the variac, so if I turn that on.

If you remember, the output of the power supply was around 31 volts, but here we only have 23. If I change my variac, you can see I’m adjusting the voltage that is coming out of the variac. Let’s go all the way to zero. Zero volts.

Let’s now connect the output of the power meter to one of the primary windings P1. Just to see what sort of output we get from the secondary S1 of this transformer, we’ll connect the secondary to the voltmeter first.

If we turn this on, if you remember, we had turned the variac right down to zero volts. If I increase that voltage, you can see how the output of the secondary of this transformer is also changing based on what our input is. But since we want to do our short-circuit test, let’s go back to zero and change our configuration slightly.

So instead of connecting our voltmeter, we’ll change the setting to ammeter, AC, and we’ll go to the 10-amp range. So right now, this ammeter is like a load to this transformer, and as we increase our input voltage, you will see the current will increase here as well because ammeter is the load.

The maximum current rating of this transformer winding, the secondary transformer winding is 1.39. We’ll see how close we get to that output. At 13.6 volts on the primary, we have a primary current of 0.256 or 256 milliamps, and our output is giving us a full current of 1.39 amps on the secondary.

That’s our part of the short-circuit test. Now, obviously there is next part to it where you have to do some calculations to understand how that affects the transformer, but this part was the short-circuit test procedure.

As you saw, we have all the components that you will need to do majority of practical tasks and assessments for the transformer’s unit of competency. If you have any questions or feedback, please feel free to get in touch with us via the email and the phone number on the screen. Thanks for watching.