Hey thanks for watching this video. This specific video is on three-phase motors, a particular type of three-phase motor, known as the dual voltage and or the part start. Motor and you'll see this a lot in larger commercial applications, because in larger three-phase commercial situations, you will see a lot of three-phase what they call 208-240 or you'll, also see some 480 volt, often also called 460., so you'll kind of hear those used interchangeably. In the same way that in the past, people would say: oh that's a 110 volt and then they went to 115 and then 120 you'll also see some will call it a 208 230, 208, 220, 460 or 480.

But you can break it down into two. Very simple ways of thinking of it: we say: 464 80 in terms of three phase: we're talking about a high voltage, so we'll call that high voltage three phase and then low voltage three phase again. This is not low voltage as in control voltage but low voltage. As in a lower voltage of main distribution power, your main power coming into the structure or into the unit that you're working on the particular system, that would be your 208, 230 240..

Now again, generally speaking, when we're working on a three-phase y system, which is the most common that we see, we will say 208 three phase and now again, if you're not familiar with three phase, it's probably better to watch a different video than this one, because i'm Going to be talking about some things and kind of glossing over what three phase is, but just a quick summary when we're working on typical 120 or 240. Those are single phase, applications we're taking one phase of power from the power company and we're splitting it into two, and so you have two legs that are 180 degrees at a phase from one another, and so that's how you get 240., but in three phase applications. You have three different sine waves that are all 120 degrees out of phase from one another. So if you think of a circle - and you break it up into three parts, they would all be 120 degrees out of phase from one another, which is why, when you go from any two phases, even though they're 120 volts to ground or neutral, there are only 208 volts thereabouts to one another, and so that's again, a very typical y, three-phase application.

There's also something called a delta, three-phase configuration, which is where you get what we would call the wild leg to ground or to neutral again. This video is not specifically about that, but just so you kind of know some of the terms in case you're, coming into this a little bit cold. So specifically, when we talk about a dual voltage motor you're, going to see, there's all these numbers - and so essentially what's happening is - is the manufacturer of this motor is splitting up the windings? So that way you can either wire them across. The line is the term that we use, where you're using a high voltage source and you're just wiring it.

So that way, the voltage goes all the way through the winding or you're splitting the winding into two parallel circuits, and so, if you pay attention to this y configuration on the left, this is the one we're going to focus on more. If you're wiring in high voltage - and that would be your 460 480 type application, you would literally wire your l1 l2 l3. That's your power coming out of your contactor! Now again we say l coming out of your contactor. That may be the t, but again we're just saying your your main legs of power, you're going to wire directly across the line literally l1 is going to go to 1 l2 is going to go to 2 line, 3 is going to go to 3 and then You're just going to connect together your 6 and 9, your 8 and 5, and your 4 and 7., and so, if you think of this very simply, if you're wiring it across the line, you're literally wiring it exactly like you would a normal motor you're just having To make some of those internal connections, you know the winding terminals that are closest to one another to make those windings whole, but if you're using a lower voltage so you're using that 208 240 volt type of situation you're now going to wire your l1 to both One and seven, and so you can see that single winding one and seven are being wired together.

Two and eight are being wired together to l2 or our second phase and then 3 and 9 are being wired together to our l3 and then we're joining together. 4. 5 and 6.. So if you take a look at that diagram, 4 5 and 6 are being wired together and those now become the center of that other three phase winding in essence, when you're wearing it in low voltage, you're, making two parallel circuits or essentially two sets of parallel.

Windings so you're essentially doing the same job now that motor in total, by the time you take into account both of those parallel circuits will draw double the current, because you have two parallel circuits at the lower voltage you're going to draw double the current, because it's Half the voltage, which will end up with the same wattage and that's just basic watts, law stuff there and again, i'm not going to bother you with a bunch of math there. But you know this from a very practical standpoint. If you were to wear this up on the high voltage across the line set up, you would see you know, let's say you're, let's say on a single leg. You measure 20 amps, we'll use that just as a as an example that i just made up.

If you wired it in the parallel application, then on one leg of each set of parallel circuits, you would read 20 amps for a total of 40 amps. So two parallel circuits 40 amps total with the lower voltage configuration. If you look over at the delta configuration, i'm not going to go through them one at a time, but it's basically the same thing again: high voltage going across the line, one two and three go to l1 l2 l3 and then you join together. Four and seven five and eight six and eight and again you're, just making two separate delta circuits.

If you go with low voltage and you're powering them independently, that's just the basic dual voltage motor, it's actually quite simple. The manufacturer is just splitting those windings in half. So that you can either create two parallel circuits in the case of low voltage or a single across the line circuit in the case of high voltage. So, let's take a look at an actual motor data tag and you can see this motor data tag on the connection diagrams on the right shows you literally how to connect it, so you don't have to memorize all this.

You can either refer back to the literature or you can even watch this video again. If you want but a lot of times, it will be on the data tag itself, and so, let's look down at where it says the voltage and the amperage. So if it's 208, then it's going to be 5 amps. If it's 230, it's going to be 4.8 amps and if it's 460, that's the high voltage wiring configuration it's going to be 2.4 amps, but just keep in mind that, depending on whether it's on the left or the right side of that, whether it's the 208 230 Or the 460, it has to be wired differently, so you'd have to wire it according to those connection diagrams.

So the top one on your right. There is your low voltage connection diagram and your bottom one is going to be your high voltage connection diagram again just using this particular motor as an example. All right now, let's talk a little bit about part start part start is something you'll hear in the field, and i want to make sure that you know what that means. In the case of a part start motor, you have a low voltage, dual voltage motor, but instead of energizing both of the windings.

At the same time, you energize one winding first and then you energize the other winding. Second - and you know, different manufacturers will call this different things. A lot of them will call it the start and then the run so you'll have, or some of it we'll call it the l and then the run. I think l stands for line, but all that means is that you're going to start by energizing one of those parallel windings.

So in this case the diagram being shown here. T1. T2 t3. That's kind of your outside winding on the y diagram you're going to energize that first and then generally in most cases it's going to be.

You know within a couple seconds uh many will say up to five seconds, but a lot of cases like with compressors we'll see it even within a second. Then it will energize the second part and the reason that they do. That is order in order to reduce in rush amp, so first energize half of that winding. Essentially you get the motor running.

It starts to reduce that inrush current and then you go to the second. Now again the motor needs to be specifically designed for this. There are a lot of dual voltage motors that you can run in. This part start configuration, but you definitely want to refer to the manufacturer's specifications.

So, just as an example, this illustration i pulled from one of the emerson bulletins, and it's specifically showing this is on a on a large um compressor. It's showing how you can wire it across the line or how it can be wired in a part, start connection type of configuration, and so you can see it's just showing you specifically for this motor, how you can wear in that part start method and there's going To be a time delay, you see how it shows a time. Delay relay so essentially you're, just creating this very quick time delay between your first set of windings and your second set of windings, which reduces inrush, and it also reduces the electrical load or the wiring. That needs to come into that particular device, so it can reduce your starter size, contactor, size, wiring sizes, things of that nature, and that's often why they will do that, because you're dealing with such a large inrush they're just kind of splitting that up you don't actually See that that often nowadays, but you will see it on occasion, especially if you work on much larger uh commercial equipment, nowadays we're seeing a lot more variable frequency drives or vfds coming in and that sort of performs the same function so that we don't need to Use this heart start type of configuration, but that's it.

That is what a dual voltage motor is and part starts. Quite simple across the line is just wiring it up like any other motor. So when you hear somebody say across the line, it just means that you're energizing the entire thing at once, with one set of controls, contactor starter, whatever you're, using to start it up or when we say part start or where you're using a multiple contact or start That just means you're splitting those up across multiple controls and you're doing that in order to have two parallel circuits. That can be because you just have lower voltage coming in and that's what you've got to do in order to power up that motor or it could be because you want to have that part - start type of configuration in order to manage those start.

Amps on that particular motor, so that's it a lot of technicians get overwhelmed with three-phase. It really isn't that complicated! You just have to follow your diagrams and take your time when you're wearing up your specific motor to make sure that you've looked at what the manufacturer says and two basic rules. Look at your data plates very carefully and also look for manufactured data and application bulletins. On proper wiring, thanks for watching we'll catch you on the next one,.