 So, three phase, how three phases reverse rotation, it's all about the way that the waveform works and I talk about it in a previous video, I've got a video on three phase power so you can go back and check that out. If you go to the YouTube channel, you can find all this stuff that's completely searchable. So what I want to show right now, just move this out of the way, is this is the control circuit. So this probably looks very familiar to anybody who's taken a motor control course or has kind of come through my course. You've got a stop switch here that's normally closed, you've got a push button here which is normally open. Again, these are all momentary contacts, I've got a forward push button and a reverse push button. Now, if I've got, not if I've got, I've also got a set of normally open contacts here that are connected to my f-coil. So if you want to know more about that, watch that relay video that I posted last week. But I've got this f-coil here, when this energizes, these guys close. Alright, because it's normally open, so when it's energized, they close. The thing also is, I've got this set of normally closed contacts here, when this energizes, these contacts open. And vice versa, when my R-coil, my reverse coil energizes, then these guys close, when my reverse contact coil energizes, these guys open. So let's walk through what this circuit really does. Now, what we don't want to have happen is you don't want this contactor and this contactor to pull in at the same time, because what that does is create a short circuit. And I'll show you that in the next slide here. So I want to, we want to make sure that never happens. So what they do is they put in two things to prevent that from happening. We have these guys here, which we call our electrical interlocks. And this dotted line here, that is the mechanical interlock. The mechanical interlock's like a paddle between the two contactors, so that when this guy pulls in, it prevents, like, holds this guy out, so it can't be, can't be energized and pulled in. Now these guys, they come along, power comes here, I push this button down, this energizes, these close, so this holds in. So that runs through, and I should do a little mini lesson on how it, just a basic start-stop three wire circuit works. So we'll talk about that holding contact there. But just trust me that that holds in. So this f-coil energizes, which allows my motor to run forward. Now at the same time, this set of contacts opens. So if I try to energize this, I can't get through this, because these contacts are open. Then I hit stop, the energizes, opens up, closes, and now I can go into reverse. So these guys here are your electrical interlocks. Now the way we have to get these guys to have the motor go forward and reverse is, like I said, we have to swap any two leads. So we have our f-coil and our r-coil. So look at this. This would be our f-set of contacts. This would be our r-set of contacts. So if we hit f, f closes, energizes, closes these static power contacts. What happens is line one goes down to T1. Line two comes down to T2. Line three comes down to T3. And so the motor runs in a certain rotation. Let's say it's going clockwise at this point. Now we hit stop and hit the reverse button. These contacts open. These contacts close. Now if you look at it, I've got line one comes down and those contacts close and line one actually goes to T3. Line two goes to T2, which it did before, and line three, sorry, goes to T1. So I've swapped out the one in the three leads here, if you trace that through, which swaps any two leads, which will now, my motor was running this way. Clockwise, now it's going to run counterclockwise. And so that is the way that we reverse it by using the power contacts, all right? Now the next question is just for those who want to know actually how does this work? Let's look at the waveform. So again, don't worry too much about this. You just got to trust me in the three phase. You have three waveforms happening and they happen 120 degrees after each other. So we have the red waveform happens, goes up, down, goes up, down 120 degrees later, the black waveform happens and 120 degrees later, the blue waveform happens, all right? So that's how three phase works. Again, I've got another video on that in my three phase. If you go to the YouTube channel, you can check that out there. So we go with the red, black, blue here in North America quite often for three phase power, red, black, blue. So what happens is this runs at red, black, blue, red, black, blue and keeps going and going and going. If we swap any two leads, here I had red, black, blue, well, what I've done now is I've swapped the blue and the red and I go blue, black, red, blue, black, red, blue, black, red and let's make more sense in a second. I'm getting to a point here other than pretty colors. Then we go back to red, black, blue and if I do another one, I can go black, red, blue. So I've swapped, I'm just showing you guys how I swapped two leads, the different permutations that that can happen. So now I have my red, black, blue wave form up here. My blue, black, red wave form right here and my black, blue, sorry, my black, red, blue wave form here. Now let's call red A, let's call black B and call blue C. When this gets going, it goes A, B, C, A, B, C, A, B, C, you see that A, B, C and keeps running, just keeps repeating itself, A, B, C, A, B, C, A, B, C. So that's what's going to give us a rotation going in one direction. Now the next one is this. I've swapped out the blue and the red. So I go blue, black, red and by doing that, I go C, B, A. So I get C, B, A, C, B, A, C, B, A. So I get my thing rotating that way. All right. The next one is I've swapped out my black and my red. So now I have B, A, C, B, A, C, B, A, C, C, so it's all changed here, right? A, B, C, A, B, C, A, B, C, C, B, A, C, B, A, C, B, A, C, B, A, C, B, A, C, C, Now let's take a look at this though. They all look sort of different right now, but they do two of these follow the same pattern. So we look at this and we look for a pattern here. C, B, A would be a good pattern to follow through. I just picked the spring to make it easy for you. C, B, A, C, B, A, C, B, A. If you look down here, this one actually follows the same pattern. C, B, A, C, B, A. See that? Mine blown. No matter what, when we swap those two leads, I either swap the one in the three lead or the one in the two lead, I end up with the same pattern going through there. So that's why when we swap any two leads, then we end up with a different rotation because when you swap the two leads, you get just the same rotation no matter what. C, B, A, C, B, A, C, B, A. And that's how that works. Now let's call me back on.