 In this video, we're going to be looking at flex linkage. I've got myself a multi-winding setup here. I've got one winding there, one winding there, one winding there, one winding there. You notice that I've got this guy down here is connected in series, and we're going to read what the voltage is on the secondary side. Now let's talk about this primary side though. It looks like I was about to do a parallel connection because I'm missing a line here. So if we follow this through, you'll see that this winding here is connected. It's got a place to go. This winding looks like it's about to be, but now it's not. It has no connection point there, which means that basically all that's going to be put on this is on this winding right here. This winding is dead to us. We're going to ignore it because it's not hooked up. So what I'm going to do is we're going to take some numbers and we're going to trace this out and see how this circuit works. Now first thing we want to do with every multi-winding transformer I've said in previous videos is get your ratings for the windings in here. So that's our first step. Take a look at my primary side here. I've got a transformer that is rated at 10 kVA. That means when we're dealing with the windings, we take that kVA and we cut it in half, and that's what each winding is worth. So that's where I get this 5 kVA from. Then I take the lower of the two voltages, the 1200 volts, and that is my winding voltage rating. So I've got that written in there. Then I take 5,000 divided by 1200 volts and that gives me 41.7 amps. That means that this winding right here is built to be able to handle 41.7 amps. Now you notice that I don't have any ratings put in this side. That's because this side as we discussed previous is not hooked up. See that point there? Not connected to anything. I don't want to put numbers here because I don't want to confuse myself at this point or confuse you. Now let's take a look at our secondary. I go ahead and I go hog wild. I take that 10 kVA, I split that mofo in half, 5 kVA, 5 kVA. Take the lower of the two voltages, 120, 120. 5,000 divided by 120 gives me 4.17 amps, 4.17 amps. Now we're going to take a look at what happens to my voltmeter, what I'm going to read on that guy with the connection that I have. Okay, now I've moved my ratings off to the side here just to get them out of the way. I've also taken this 1200 volts and this 120 volts and I've worked out my winding to winding ratio of 10 to 1. Then I've got this 1200 volts that is actually put on this transformer. So what I've done is I've taken this 1200 volts and I've moved it down to here. This one winding here has 1200 volts impressed across it. Now this is where the magic of flux linkage happens. The flux that is being impressed on this guy, it is sharing its flux just like you would think with this winding here as well. But at the same time these guys are also close together that this flux is also cutting this side as well. And yeah, it's actually cutting this as well, which would mean that if you took a voltmeter across there and there you would see a voltage. So don't go ahead and lick those points because that will end up giving you a zap. But that's for another video for another time. But the important part of flux linkage is this. The flux from this side links with that as well as with that. So using this 10 to 1 ratio, this 1200 volts gives me 120 volts there, 1200 divided by 10, as well as 120 volts there. It doesn't affect my voltage at all. So when I've got this voltmeter hooked up, we're going to see what the voltmeter reads here. Just as you would suspect, it is reading 240 volts. So our voltages are fine. It's acting like there's nothing wrong with this transformer. Well then what's the problem you're wondering? The problem is this. We are going to now take this guy and replace it with a load. And we're going to try to figure out what would be the maximum KVA that this load could ask for. Okay, so let's take a look at that. All right, here we go. I've taken that voltmeter and I put this load in here and I'm saying, okay, this load here is going to draw 240 volts. What is the maximum KVA that this load could safely ask for without burning out this whole transformer? So what we can do here is let's look at our secondary side. We see that right now it's giving me 240 volts on there. And then we look to see what is the maximum current that this configuration can give us. Well, we see that these two windings are in series. In series, your current stays the same. Am I right? And I know I am. Which means that this is 41.7 amps, which is the winding rating. Well, it's in series, so it's going to be 41.7 amps the whole way across. So if I want to find out what is the maximum that this side can ask for, I just take 240 volts and I multiply that by 41.7 amps. And then we're looking at that and it's 10 KVA. And again, you're thinking, well, that's great. Nothing's changed. This flux linkage is amazing. However, let's take a look at this. This side can safely ask for 10 KVA. That is for sure. But if we go back and we look at the ratings of this guy here, what is the maximum KVA that this one winding can handle? It's five KVA. So even though that this side could safely go ahead and ask for 10 KVA, we also have to look at what the primary is doing here. Because remember, whatever the secondary asked for, the primary has to give. So yes, this guy could safely ask for 10 KVA, not a problem. However, whatever he asked for, this poor little fellow, this one winding whose buddy is buggered off, he can only give out half of that. So he can only give out five KVA. So if I was to ask you, what is the maximum KVA that this load could safely handle for this transformer? Because we only have one winding up top, it is five KVA. And that is the downside to flux linkage. The nice thing is though, if you have one winding burnout, then you can keep everything going, you have the same voltages, you just need to make sure that you have some of your loads turned off and keep that current down so that until we can get a transformer in there with, you know, to replace it or to fix it. So that's flux linkage.