What is the Difference Between Single Phase and Three Phase???

what's going on my friends dustin with electrician you today we are going to talk about the difference between single phase and three-phase power [Music] so when we talk about single phase and three phase what are we actually saying let's start out with single phase single phase means we literally have a single loop a single circuit i know that when we think of like at a house you know we've got a house over here that's a terrible house we got the service we got a weather head that comes up here and we've got conductors that go over and hook up to each one of these we look at that and we say well we have two circuits right we have two phases a black and a red and then a white so like how is that one loop how is that only one circuit why do we call it single phase because in the utility generation portion of this um we only have one circuit so through this generator we have a single circuit copper touching from literally here all the way through the transformer on the primary winding then we have a secondary which is completely isolated it's not touching in any way so just one big loop of current and in single phase what we have is like really out in the field this is not red if you ever look at the conductors as you're driving down the highway there's just two black conductors it's not a black and red so it's really just a single loop that goes all the way out into the field but during the traveling of the of the current to the load and the traveling coming back there's actually a pushing and a pulling motion that's happening at the same time so you can think of it literally as one just large piece of wire with um you know that starts here and and ends over there well so it starts here and goes all the way through and ends back here but it has to go through a load of some sort to kind of slow that current down so we can actually do work over here and make it useful so while you can think of single phase as a single loop you need to understand that there's two different things happening at the same time so current is always going to be traveling in one direction coming out of that generator generator but it's coming back the other direction in equal magnitude at the exact same time so you can kind of think of this motion like it's pulling and pushing at the same time through that whole circuit it's not just like pushing and then pulling both are happening at that load so when we look at something like this if you look at like single phase generation at a generator you're going to have some kind of like motion of some sort that's going to move some kind of turbine essentially that's going to start a spinning motion so at hoover dam we might have water that's falling on this thing and it's actually turning a turbine or you might have wind and like a solar farm somewhere that's turning a turbine that motion is connected to a shaft inside of here and that shaft has magnets on it that can they all look a little different this is not how it actually looks i'm just like this is the concept the the conceptualization of all of it for analogy's sake but this rod this uh this rotor actually starts to turn and as it turns there's magnets on it and as those magnets turn they're right next to these conductors so you we would know from you know the basics foundations of electrical theory that when you have a magnet and you bring it next to a conductor you can actually uh induce current flow in those conductors so we're inducing motion in this circuit and so there's probably a pole that's like more on one side and a pole that's more on the other side and so as it is pushing as it's spinning it's pushing current in this way but the other side of the magnet is also pulling current this way at the exact same time so it's alternating uh you know 60 times a second but that's all that's happening is we literally have just one big loop of wire and we have a magnet next to it spinning that is just non-stop spinning and it's creating this push-pull push-pull or push and pull at the same time and then a push and pull that changes polarity and to better understand that let's look at a sine wave so sine wave is is not how current travels people are like well does what does the sine wave even mean is there like sine waves going through wires or something no it has nothing to do with that a sine wave is just a graphical visual representation that we can make for something that has 360 degrees of rotation so anything that rotates we use a two dimensional graph to display what's happening during 360 degrees of that rotational cycle so let's say we've got this and this is 360 degrees or zero you can think of it either way this is 90 degrees this is 180 degrees this is 270 degrees all of you that were in algebra algebra 2 calculus precal trig you should recognize this right so a sine wave what all it's saying is that at 360 degrees where this thing starts or at zero as this thing spins this could be the magnet inside of the generator so we've got a positive and a north and a south as this thing is spinning and it gets up to 90 degrees it's actually at its maximum that current is flowing through this conductor and when we get back to the zero crossing this is zero uh so this is what we call the zero crossing once we get back down to the zero crossing we're back flat again so the magnets inside of this thing might actually be or so the conductors inside of this thing might actually be here and here and right here there's no conductor so there's actually no current flow but once we get one of the poles of that magnet closer to that conductor it actually increases it to a maximum and then as we keep rotating we drop back and there's no conductor in either either one of the the poles but then it just keeps spinning but now instead of this current that's leaving here out of this conductor pushing it's got the south pole and the magnet on it so now as this goes up down here is pushing and over here is pulling and it just keeps doing that over and over so we have this push that's happening and it drops back to nothing and then we have a pull that's happening and it drops back to nothing and we just keep doing that that rotation is creating positive negative push pull push pull push pull push pull 60 times a second they time the spinning of this 60 times per second that's what we call 60 hertz so that's essentially single phase that's what a sine wave and all that means now one thing you could do to think about this is this is a graphical representation of what's happening over the entire circuit but to think about how current is flowing i find it useful to draw the red side of it like this because as time goes on throughout this motion you actually have the north pole side of this magnet and the south pole side of this magnet that are affecting the circuit equally so as the north pole is pushing current down one side of that current one side of that circuit the south pole is also pulling at the same time so you can see that both the push and the pull are of equal magnitude and they're equally at nothing when they're not next to a conductor so that is single phase now let's move forward to three-phase so same kind of thing three-phase we have power generation three-phase literally just means three circuits three loops and these loops are kind of tied together in a certain way where they can all share the current that's going through all three of these circuits at the same time so they're not three completely isolated loops they're three loops that are connected together in a way that current can flow uh weirdly through all of them and they can kind of share the load that's happening through three different circuits so one way to think about this is we've got three generators three complete loops so from black here we've got a loop that goes to red and it goes through and back to this motor so it's connected in a loop but at the same time we also have red to blue so it goes all the way through there you see we have a completed circuit but then we also have red to black so we've got or i'm sorry blue to black so we've got blue goes all the way over black over here back to that so they're all connected to each other so current can literally travel through all of these generators through all of these circuits and out to a load and it does the same thing at a transformer say we have a delta y transformer there's an air gap in between the primary and the secondary of this so they're actually on the secondary side up on the pole on that transformer there are conductors that are part of the primary circuit and we call those primary we usually label that with a p and then we've got secondary which are isolated completely by an air gap so any current flowing in the primary through magnetism allows current to start getting pulled in the secondary as well when you hold two conductors right next to each other and one of them's got current the other one has current too depending on the device and how you do all of that but that's what induction is so we have we have to have circuits right so at our house we're on the secondary circuit we're not on the primary circuit the primary circuits spin and doing its alternating current thing secondary circuit we'll say down in the building we've got blue these aren't in the right order you know right to left or anything like that in proper phase order but there we have three phase that we would run to a building you know and we've got on the building we've got a service and we've got a weather head just like we did uh before where we will have three phase run into that building so this is the secondary circuit so again complete loop complete circuit from the transformer up here we can kind of think of the transformer as the source for us where the source for the primary circuit is the generators and it's going to a load to the transformer it completely inverses on the secondary side so that we have the transformer that's providing a loop to the loads and we'll have motors and all kinds of things so the transformer secondary is driving all of the loads in here whereas on the primary circuit the loads are generating the current to the primary side of that transformer so they're kind of inverse of the same thing but it's just important to note we're talking about complete loops right complete circuits current cannot flow without them so what's really interesting to note is how all of this works there's a relationship of 120 degrees that these magnets are set apart in when they're being generated there's a still rotational motion but there's three different rotational motions happening and they're not all spinning together like this there's like one like this and one like this and one like this and they're they're 120 degrees out of phase of each other so while current is kind of pushing on one really strong it's going to be kind of barely pulling like pulling a little bit and pulling a little bit on the other two and they keep changing as the rotation goes the other one will start pushing and the other two will start pulling but there's always a relation of like two of them are kind of pushing at the same time one's pulling or two of them are kind of pulling while one other one's pushing there's never a point where there's not current flowing in the circuits so if you look at the generator you know like we had in our finger our single phase example we still have rotational motion somehow that's being uh externally um introduced into the generation um so like you know might have wind or something or water or whatever we still have that same kind of shaft which is you know we can think of this as a shaft or this is like the end of the shaft if you look down at this way this is not how these actually work i don't know i've never seen the inside of one of these big utility generators but i'm conceptualizing again how this rotational motion works so that you have something visual you can tie your understanding to so if we think about the this this shaft that goes through these three generators kind of like a uh a camshaft a camshaft is gonna allow like a magnetic field on uh one part of the circuit and then we're going to have another part of it on a different part of the circuit and then we might have another part of it so that as this thing's spinning none of these are actually pointing the same direction one of them is pushing current while the other one's kind of pulling it and kind of pulling it and as it spins it changes the nature of which one's pulling in which direction so i drew this as kind of an understanding of like you know camshaft essentially you're gonna look down at and you're gonna have one of these like lobes that is at uh at one position and then 120 degrees from that you're gonna have another one that's kind of at its top dead center or whatever you can think of it's maximum amplitude and then you have your third phase so there's 120 degrees between all of these things so each one of these is pointing 120 degrees differently and as it spins it's pushing or it's pulling it's doing the same thing as single phase but the one loop uh that's connected to this one is just at 120 degrees to the loop connected to this one they're all still connected current has to flow through all of them through the complete system to allow all this to happen but they're just positioned in a way that they're 120 degrees apart so we look at a sine wave for this and it's a little bit crazier because we have three different circuits that we're talking about in the same graph rather than one circuit that we're talking about so when we say 120 degrees out of phase we're not talking about the actual rotation of the motion when we say 120 degrees we're saying each one of their 100 360 degrees of rotational motion that each one of these circuits goes through is at 120 degrees apart from each other so that you'll see like right here where the maximum point of each one of these the full current flow max current is actually at the point where the two minimum currents meet up for the other two same thing over here you look at the maximum and the negative polarity that's where you have the minimums where the other two meet up so there is no point along this line where any of this current the current actually is like an entire bandwidth of current in a three-phase environment that's pushing so you don't ever have this pulsing effect whether it's an on and off like you would uh over here every time these swell and come back you have a point where there's no efficiency there's no work being done because it completely stops but in a three-phase you don't have that that's why a three-phase is used in a lot of commercial buildings and industrial motors and machines and things like that because there's no point where there's not current flowing it's so efficient and so strong and you have three circuits holding doing all the leg work of that work for you so when we say 120 degrees just understand that we're talking about each one of the generators each one of the circuits is 120 degrees out of phase with each other um in respect to how they're generated so if we look at rotationally uh say we've still got the three uh 360 degree diagrams that we're going to look at to try to understand this we still got zero we still got 180 i'm not going to do all of these still got 90 and 270. so while we might have on this black you know it looks it still says 180 and 360 and you're like well wait shouldn't say 120 no again it has nothing to do with the uh rotation of this thing and where the where that's set up it's still the same thing per circuit each circuit has its own rotation it goes through so when this when this magnet inside of this thing spins it's still at 90 degrees we'll say that you know our conductors are here and here but this one they might be here and here and this one they might be here and here so as this one is spinning we get uh 90 degrees of current up here and then it goes back down to nothing but the other one while it is spinning is going to be decreasing its magnet well it would probably be this one this one's coming from its maximum here but it starts to decrease once we get to that 90 degree mark and as we keep going we get to our maximum the maximum is not at 180 once this thing spins at 180 degrees we're still not at our maximum yet we have to keep going past 180 degrees to get to its maximum because these are 120 degrees apart so say that we took each one of our phases and we drew a line right we got blue phase and then we say 120 degrees from the top of this down to the top of this as it were to spin that's 120 degrees difference and then we have this one over here so if we keep spinning this thing it goes through another 120 degrees so we've got these three different things that are rotating and that's what allows each one to kind of have like a push on one and a slight pull and a slight pull on the other ones and then they just keep changing directions so i don't mean to keep beating that with a dead horse but a lot of people don't really understand that they think that there's like one circuit that somehow has like three wires coming off of it or something like that and it's not it kind of is how it's all run through the generation you know you can think of it being one you know giant circuit but there's no point where like all three of the wires ever touch each other that's why you're never going to take a multimeter and go to like three conductors it's only a relationship between two things on a circuit so it's always a relationship between two conductors that we're talking about you may still have a three pole breaker where you're running three conductors into a breaker and three conductors out to a breaker or you could have what's called single phase in a three-phase system where you're only using two of the conductors to make one loop you don't need all of it going for that specific motor so each one's a little bit different [Music] now speaking of three-phase wiring something that you might see in a three-phase environment is this guy um lebron is always sending me really really cool stuff so they wanted me to share this with you this is their brand new mixed-use commercial grade rfpa box so it's a floor box and it's meant to you know kind of like in in houses you're gonna have floor plugs underneath couches and stuff like that so you can actually walk across the floor and there's receptacles in the floor similar kind of thing a little bit more versatile though so you have a two gang a four gang and a six gang option and they're actually coming out with the 10 game option pretty soon uh this year in 2022 but what's neat about this is a the versatility so you can kind of put whatever devices inside of it that you want it doesn't come with devices that is something that you have to put your own devices in and configure it how you want but the really neat thing is on the inside how they've engineered uh the rounded corners on everything in here so you can actually pull conductors through this and there's not any sharp edges or anything that's going to nick up your conductors so it just saves time and it saves you you know having to pull out all of your mistakes and repo wires because you just nicked up all the conductors it also comes in a bunch of different variations so they've got round tops they've got different colors they've got different profiles so there's a lot of different options so you it's really versatile the types of enclosures as well as the types of devices that you can put them in they do have different styles for direct burial as well as at-grade or above-grade installations the reason this has a green coating on it is because it has a special fusion bonded epoxy corrosion resistant paint on it which makes it able to be put in concrete but if you were going to put something at grade or above grade not actually in the concrete they have just a standard zinc plated option as well another cool thing is you see all these different options knockouts all over it it already comes with knockout options some of their stuff has up to one inch knockout so it has two inch knockouts just depending on what model you get but this is a really really well engineered uh well-designed floor box so if you are looking for a floor box that is really versatile that you can put all kinds of cool stuff in get this link in the description below so also not just generators can be uh three-phase actual loads can be three-phase as well so when you have a three-phase load we'll say that this is a motor there's actually current coming through say we hook up a black to this we hook up a red conductor to this this is coming from a breaker at a panel somewhere we have three uh places where we're tapping into this motor and because there's current traveling forward and a little bit backwards and a little bit backwards on this there's kind of already this like spinning motion that we're doing to this thing so it makes this thing spin over and over and over and that's how a three-phase motor works um single-phase motor is just a little bit different than that you could still have like blue and red phase we could say on a three-phase coming from a three-phase panel but you don't need three phases to run this motor you only need a single-phase circuit you don't need three different circuits so you would still run just two conductors and we would call that single phasing something if it's a three-phase environment but you're only using a single phase of it we would call that single phase as well but you could run this whole motor from a circuit this way the interesting thing with single-phase motors though is a lot of times they have to have a capacitor because remember what we were saying about this whole like rotational motion this field if we've got a conductor here and a conductor here and we're spinning and there's no conductors right here there's no current so that magnet can actually get stuck in there and it won't move because there's nothing creating anything to like push it to get it to go so a motor on its starting circuit you might have a capacitor a capacitor is just something that like hooks up and as current goes through the capacitor it makes the the uh the phase shift a little bit so it actually shifts voltage and current enough so that it has a build up of potential and delays the current a little bit just enough so that it can it can uh time itself correctly to spin where the conductor is and then when there's no conductor there's a delay that releases the current through that capacitor uh that charges and then discharges late so that it still gives it a kick to go around so that's what a starting capacitor does is it just provides a delayed hit to a single phase motor to allow it to start spinning but that's it that single phase in three phase probably went way more than i should have let me know if you have any questions [Music] this can't music and video you

Channel: Electrician U

Views: 326,697

Keywords: electrician, electrical, electricity, dustin stelzer, electrician vlog, construction, commercial, residential, electrical courses, electrical class, electrician class, electrician school, current affairs, faulty, voltage divider rule, amp, what is voltage, alternating current, current electricity, current affairs today, electronics engineering, single phase transformer, three phase, 3 phase, 1 phase vs 3 phase, one phase atheon, 1 phase motor, electricial, three phase explained

Id: FEydcr4wJw0

Length: 23min 11sec (1391 seconds)

Published: Wed Mar 16 2022

Reddit Comments

[u/Care-Extension]

2

[u/Care-Extension]

2