I remember my EE professor from my undergraduate days filling three chalk boards with a beautiful derivation of WHY three phase power, why not 4, 5 or n phase power? Answer: Because three phases was the minimum number of phases whose average power was a constant. Additional phases require additional windings and transformers, so go with THREE phases for the most efficient power grid. Beautiful. How I wish I had a video of his derivation. Even after over forty years as a now semi-retired Electrical Engineer who dealt with RF systems (FM broadcast, TV broadcast, and microwave), it was masterful derivation.
@@theachebes5724 Not on 60 Hz AC power. My AC power/motors experience ended with college. My experience is in RF-- its propagation, and also loss/gain calculations for hight power radio and TV stations. Did several 5 MW ERP/60 to 80 kW TPO analog TV designs, but with digital the maximum allowable ERP is just 1 MW, so TPO's are typically in the 40 to 50 kW range. Still, it's 6-inch rigid coax line to handle the power. No more waveguide transmission lines, given that UHF TV now stops at Channel 36 (605 MHz) instead of Channel 69 (803 MHz).
120V/240V "residential" power comes from a single 240V phase supply line produced from a step-down transformer (secondary side). The primary side of the transformer is fed by one phase (1 of the 3 phases) from the substation (commonly 12kV). The secondary side of the transformer is stepped down to a 240V SINGLE phase output. Because the secondary of the transformer is split into two halves with the neutral (or ground) at the middle of the transformer's secondary winding, two 120V reference-to-ground signals are produced. So there are 3 wires coming from the secondary of that transformer, (2 hot--1 wire on each end of the winding, 1 neutral/ground wire tap at the middle of the winding). Measuring the voltage potential from each hot wire to the neutral wire yields 120V. Measuring the potential difference from one end of the winding to the other end yields 240V (ie. 120V + 120V...actually, 120V minus a negative 120V). This configuration is also called a split-phase system. I added this comment because at 8:00 of this video, it's not clear enough, because it says "it's 2 single phase lines". Technically, it's one phase split into two halves and the waveforms are "out of phase" only because they are referenced to ground at the middle of the transformer winding.
@@fuckjewtube69 here’s my understanding, take it for educational purposes, not instructional or safety purposes: the neutral wire DOES carry current, specifically the returning current through the home’s loads (ie. lightbulbs, tv’s, appliances, etc…). The neutral wires coming from the loads in a home’s breaker panel are tied to ground and the neutral wire coming from the secondary transformer is also tied to ground at the pole. Because neutrals are tied to ground, the Voltage potential from the neutral wire to ground is minimal. Power can be calculated by multiplying Voltage by the current (Amps). If there is practically 0 volts on a wire, then the power is going to be ~0 as well. **That is why it is possible for a person standing on the ground to touch a home’s bare neutral wire without getting shocked. It is also why the neutral wire coming from the pole transformer into a home is a bare conductor (no insulation). **If there are situations like lost/disconnected neutrals or grounds; ground faults where limbs of a tree touch bare high voltage wires; etc… then this statement may not always be true, it may be possible to get shocked. In summary, it’s about completing a path for current to flow, but also how much force (aka Voltage) behind the current flow; and it depends on exactly what two points in the electrical loop/circuit are being touched/connected in order to cause current to flow.
Great explanation of three phase. My son is entering the generation field and this will surely help him better understand three phase vs single phase. Me, 30+ years in hydro generation, so sometimes Dads explanations might be a little over whelming. Thanks.
This begins with faulty description of the effect of the north pole of a magnet rotating by a fixed linear conductor. Electrons do not flow towards the north pole of the magnet. According to Lenz's Law, the electrons in the conductor flow in such a direction as to oppose the motion of the passing north pole. That means that as the north pole approaches the end of the linear conductor, the electrons flow in such a way as to create a north pole at its end. As the north pole passes and receded from the conductor, the electron reverse their flow so as to produce a south pole at its end, to attract the receding pole. Lenz's Law is really a consequence of Faraday's Law of Induction, which states in mathematical terms that the direction the induced magnetic field is always opposite to the direction in which the magnetic field is increasing. The electrons in the conduction flow in the direction required to produce that opposing field. In the mathematical expression, the negative sign is what Lenz's Law expresses in words.
The conductors between a voltage source and a load are called lines, and the voltage between any two lines is called line voltage. The voltage measured between any line and neutral is called phase voltage. For example, for a 208/120 volt service, the line voltage is 208 Volts, and the phase voltage is 120 Volts.(9:32) EU: 230VAC => Phase voltage 400VAC => Line voltage.
@@enyakang6950 Yes. He meant "I was only wondering about 3 phase for about 25 years ..." but another way of saying it would be "I've only been wondering about ...". So he probably started one way then switched to the other without noticing. As you probably noticed, the "only" is ironic, because 25 years is really a very long time to wonder about something. Only been wondering for 25 years! I've been wondering for longer, as I'm probably older and it's a long time since I first heard the term.
as an EE I want this video to be tough in colleges, it explains it perfectly , I want to go back to college, who would not want to be in college -all you have to do i study nothing else lol kids these days have it made with the internet, this is a great video, I watched it twice because its so well done, who ever did the animation I want them to do my power point stuff and make it like this
Another, unmentioned, benefit of 3-phase power is that 3-phase AC induction motors are much simpler, not needing a shaded-pole device on the field windings or a special startup motor to get the principal motor started. A 2-phase AC induction motor, like an internal-combustion engine, can keep itself going but needs a separate device to get it started.
True (sorta). It is actually 2 phases, but they are phase locked 180 degrees apart and we have access to the 2 hots and that center tap. So in reality, it is a combination of both single and double phase. Imagine if someone had 2 lines each 120V and each having a neutral center tapped to the same transformer's secondary winding. Next imagine if they could put say a 45 degree delay in one of those lines. Would it then still be single phase or 2 phase? If 2 phase, then you are saying that when 2 lines are 180 degrees apart it is single phase but is it really? Some people would agree and some would disagree.
If the starter winding is out or the centrifugal switch is non-functional, you can hand-spin a single-phase motor and it will run both ways. We had a bench grinder with a failed "cent" switch that would have sent power to the start winding. I put a momentary-contact switch in the start circuit, and then at the moment I would turn on the grinder I would push the added switch until it got up to speed, and then let that switch go and all was well! It we didn't hit that switch the motor would howl and not turn. If I hand-spun the grinder wheel backward and then did the other steps before it stopped drifting backward it would run in the wrong direction! Also, if I am not mistaken, the 3-pase motor was invented first, and it was supposedly a battle to make an effective single-phase motor after that.
Been studying for an upcoming test and needed some refresher material. You explain the material beautifully. Definitely have a knack for explaining complex processes in a simplified manner.
Very good very clear explanation, l have been looking at this stuff for years and for some reason for me it just takes one mind and l know......yippee....what a life ...does it ever puzzle you why we have to search for so long before we find the right answer ....why can't we get it straight away
@@mikeymcmikeface5599 i dont think it does becuz only one line will ever be perpendicular to the magnet every time it rotates while the other two will be parrallel to the magnet
Errata: At 0:40, the sine waves are 60 degrees apart, but they should be 120. Magnets do not attract or repulse electrons. Varying magnetic fields cause electrons to experience a perpendicular force, which is why you need coils in a generator and motor, straight wires would not work properly...
thanks for this. I'm a recruiter and working with construction and 3 phase power is a huge plus for what I'm hiring for. Your videos do a great job explaining this to a layperson w/o the background.
you don't want a lay person without the background working on 3 phase, lol, lmfao, pmsl and ha ha. not unless you have a good Hoover to clean up the little pile of dust that will be left where he once stood 💥😵🌬💨👋
Practically all automotive alternators are three phase, when rectified, the ripple voltage was less that 8%, single phase is 100%, no need for huge capacitors. Ideal in plants when AC had to be converted to DC. Three phase motors were very efficient. Three phases 120 degrees apart inherently generated a rotating field, without capacitors so motors could be made much smaller. Wish we had three phase in our homes especially for air and refrigeration compressors and fans.
for people who might don't understand this comment but will understand after this reply: 1 phase ac motors are actually 2 phase, since 1 phase would be impossible to synchronize. in order to get 2 phase from 1 phase, you would need a capacitor 2 phase electricity has a sine wave with 90 degrees offset from the first
You suggest that electrons are attracted / distracted by a magnetic field. That's wrong. It's the changing magnetic field that causes an electric voltage in the coils.
The waveforms at 4:50 and 5:25 look totally different. Why is the first one asymmetrical, as if the waves are grouped together? Just a crappy animation?
@@joshbachman7706 indeed Industrial inverter drives are brilliant for matching speed matching ramps or current limit I have fitted thousands from 0.05kW up to 3000kW fun days.
At trade school 40 years ago we studied the GM delcotron alternator.. the study materials called it the six sweeps of the alternator... which btw are all three phase... great video!
Nice job. Working as an EE in the power field for 40+ years its always been easy for me to understand but difficult to explain to laymen....especially on a napkin with a pen. 😊
Unfortunately this doesn't show a very good representation or explanation of how an AC generator moves electrons around, but there are a number of other good concepts in the video that help explain the basics of AC power. Electrons need a loop of wire to move around, and if that were shown (and it has to be in a specific orientation), we'd see that electrons move both towards and away from a magnetic pole in an AC circuit. If it were as simple as saying electrons were attracted to a "+" or "-" as in a DC circuit, they wouldn't be able to move around the loop at all. A better explanation is that the magnetic forces of a north pole push electrons in one direction around a loop and a south pole pushes them in the other direction. In between poles the magnetic forces are near zero so the electrons stop. Further, electrons only move in a changing magnetic field so the magnetic poles have to always be moving or the wires themselves have to be moving. In a large generator magnets rotate (spin) horizontally inside stationary coils made of copper bars that run vertically and the electrons move up or down in the bars depending on whether a north or south pole is acting on them. They also move perpendicular to both the magnetic field and direction of rotation (see Flemings Right Hand Rule for Generators).
Scott J Electrons do not necessarily need a wire to move about. Electrostatic charge is one example. Electron beam is another. Old CRT TVs used the steered electron beam for half a century. There are scan converters that still use them today. Then there is always radio. Electrons are not pushed anywhere. They are lured to an electron depleted field through what ever means they can. Open space requires very high potential levels, metal conductors very little. This is a small sample of what you left out of your educated reply.
Bryan St.Martin, Although everything you've said is true, it's irrelevant to the understanding of 3-phase power and the functioning of electric motors. The current in an antenna is negligible compared to the current in an electric motor, generator, or transformer where the electrical circuit is complete. I do agree with Scott J that the pictures in this video demonstrating the magnet and the current in the wire are a bit wonky. The video makes it appear that electrons are attracted to the north pole of a magnet, and repelled from the south pole. If this were true, we could obtain free energy by using magnets instead of batteries. Rather it's the moving magnetic field that induces a force on the electrons. Neither the pictures, nor the explanation in this video explain this, and in fact imply that this is not true. For someone who doesn't understand these things and who is trying to learn, this is going to cause a lot of confusion.
There's a reason he said at the beginning of the video that this video requires an understanding of how AC power works, and that if you don't have such an understanding you should watch the video on AC power first. You're criticising this video for something that was explicitly stated would not be in the video. It's like someone saying they are going to show you how to cook pasta, and you're complaining that they skipped over how stovetops work.
Jeffery Wells, I'm criticizing the video because what he's showing is not only confusing, it's wrong. The north pole of a magnet does NOT attract electrons. The wires have to be moving perpendicular to the magnetic flux lines in order for there to be a force on the electrons. The wire has to be oriented so that force is in a direction that causes current to travel through the wire. What is shown in this video will cause no current at all.
Scott, I'm the creator of the video. If you watch the first video, you'll see and hear where I say that while I SHOULD show a loop of wire (per your comment) BUT in order to keep things simple, I will only show half. The issues with creating these types of 7-10 minute videos are: what do I include and what do i cut; what analogies do I use to explain the basic concepts which are rarely well explained. I decided that showing a looping wire would be harder to visualize and animate. It would also open more esoteric topics. My goal was to explain the topic to people who didn't understand 3 phase.
Data centers, and other commercial and industrial buildings don't necessarily use 3 phase power because of less amperes; it is because 3 phase power provides a "more balanced system". Such buildings demand more power than dwellings even though dwellings are served with lower voltage power.
I hope that you can make a video using three phase graph to educate rookie electricians about the danger of letting the phase wires to touch each other in electrical wiring, as three phase wiring nowadays is more popular for domestic electrical wiring compared to single phase
Altough the information in this video is completely correct, still one question was not answered: why 3 phases? why not 2, 4, 5, 6? why 3? And there is ONE major reason why 3 phase power is the way to go and the reason is the same why 1, 2, 4 phase power sucks. 5 phase power supply would have been the next choice. why? because power output over time is constant with 3, 5, 6, 7, 9 and so on phases (uneven numbers and any nmultiples of those)
yeah.. that video doesn't explain anything, because the numbers seem to be chosen arbitrarily. so.. no real background there. again: after 3 phase power the next possible number of phases would have been 5 for the reason of a steady power output. but it can be explained quite easy why 3 phases were the way to go - there is no need for a 4 minute long explaination.
Hace mas de 100 años, en los inicios de la electricidad, se probaron sistemas de varias fases, pero el sistema que venció a los demás fué el trifásico.
Here's a simple answer - the cost of copper. The detailed answer is a very technical analysis of cost of additional copper for each phase versus the increased "performance" of more phases.
the need for an alternating current with constant power output (and not any sin-wave power!) came from electric locomotives. they would slip with a power peak coming for example from a single-phase sin-wave power. when slipping, the friction reduces a lot limiting the capibilities of it! but with a constant power output the trains could be built smaller and more efficient. and again: 3 phases, 5 phases, 6 phases, 7, 9, 10, 11, 12, 13, 14, 15, ..(any uneven and multiples of those uneven numbers mentioned before) have a constant power output over time. and obviously when they all do the trick why use more than 3 phases? wouldn't have made sense in any way (yes, cost, but also complexicity). always think of the histrory of the technical system you have in front of you and electricity wasn't always for wide public use! then tesla and westinghouse had their stupid fight over AC vs DC is was already decided in europe to use 3 phase AC. that's what noone from the north-american continent seems to know and maybe they just don't want to know..?
Voltage is a potential difference between two points. It doesn't make sense to say that a line carries 120 volts. You need to state the configuration precisely.
good video the way the narrator tries to go slowly through the material to make sure it gels and gets absorbed. Sadly at this point in time there are 333 dislikes meaning there are 333 confused people out there still scratching their heads with a bewildered look on their faces.
the real reasons for three-phase are: firstly that it is impossible to manufacture a high power single-phase alternator (see Leblanc's theorem and the theory of rotating magnetic fields, so-called reverse magnetic fields in a single-phase alternator are disastrous), an alternator of more than a few kva is necessarily polyphase. secondly it is possible to transport more power on a balanced three-phase line (same current in all three phases) with the same amount of copper as with a single-phase line, this is a basic demonstration in electrical engineering training. for three-phase motors, three phases are sufficient to generate a rotating magnetic field of constant amplitude and constant speed of rotation (proportional to frequency, Ferraris theorem). The mechanical torque of these motors is not affected by the sinusoidal shape of the power supply. 6- or 12-phase networks have sometimes been used to fabricate rectified direct current with low ripple residue.
At 4:48 the wave forms are not 120˚ apart. I thought that you did not understand. Later on you make it clear that you do. I knew that 3 phase had something to do with generator layout. You made that clear.
It's just how the AC power is transmitted, it's 120 degrees out of phase from each other. The magnet is the generator that is generating the power i.e. Hydro-electric Turbine at a Dam.
I don't understand the 10.8kVA calculation. I get how each pair gives 208V x 30A. But why do you multiply by 1.732 again to get the total power for three pairs? Why not multiply by three?
If you look at each individual leg, you have 120V X 30 A = 3600W, then you can multiply by 3 and get 10800 W total, but taking each 2 leg pair and multiplying by 3 doesn't work because each of the 3 legs, A, B, and C is shared in 2 pairs (A to B, B to C, and C to A) and thus, each leg cannot devote its total power to each of the 2 pairs it is simultaneously powering. There has to be a derating for sharing the lines and when the calculus of the RMS sinusoid wave form is done that all these overlapping sinusoid wave forms come from (it's been years and calculus escapes me now), there are definite integrals that solve down to the square root of 3 as the deciding factor to multiply by.
You can multiply by 3 but then you have to use the phase voltage 120 V. The power you get is same whether you connect to star or delta. It is just simpler to understand the star connection as you can essentially for get the phase angles and view it as three 120 V circuits so 3x the power.
I was hoping he would talk about how the Utility people go about routing Three Phase power through a town, versus how they go about routing more ordinary 220vac Single Phase power around a town.
The windings of a 3 phase generator are 120 degrees apart. It would seem reasonable that the power coming from a 3 phase generator would reflect the 120 degree locations of the generator windings. It would be an interesting experiment to wind a generator with the coils located at different degree locations and observe the phase pattern david
I read a paper on 5 phase systems a decade or two back. Very interesting, and extremely smooth operating. Imagine building a Bridge Rectifier for that. Tremendous torque.
Explanation is quite good enough but the rotating magnetic field is generated after current passes we should not place magnet before to understand this that makes it complicated.
Id be one of those people but it's hard to avoid the brainwashing terminology of the ac power fans. Hot neutral and earth? Isn't it power, ground, and redundant ground? Also wouldn't a pulsing DC run a transformer just the same? I mean unless ignition coils are some sort of black magic.
There is always a real component (I.e watts) in power calculation of AC circuits. Apparent power includes the real and imaginary vectors in the calculation and units is VA. Most electricians widely misuse these units and how to calculate them.
"Positive and negative phase don't cancel" Meaning the AC frequency is non destructive? I'm not 100% sure what you meant, could you clarify? Plus and minus should offset eachother.
The _radical symbol_ *√* is NOT an "r"-it is a mathematic symbol. *√3* means _the square root of 3._ Or, _3 to the power of_ ½. *√3 ≈ 1.7320508075688772935274463415059*
If you don’t understand trigonometry, you just have to accept that you multiply 120 by the square root of 3, or 1.732, to get 208. Trigonometry tells you why. The why may be useful sometimes.
Most of the negative comments are dealing in symantics While they may be correct technically the method of showing the process is successful. Besides, who gets thier electrical engineering degree from youtube videos? Chill tf out. Nobody's gonna get killed because the video didn't follow every rule of science in the illustration.
Almost all of my higher voltage "Data Center" equipment (Printers, CISC based CPU and HD Racks) required 240v as standard. When we relocated and the power company could only supply 208v to our facility we had to have the manufacturer come out and make adjustments to operate on the reduced voltage. At least now I think I understand where the 208v came from, but why is 240v 3 phase standard for so much of the older, heavier equipment and household appliances such as stoves and dryers?
Because there was/is a common configuration that is 120V to ground on 2 legs with a stinger leg which is 208V to ground. They are 240 delta with a center grounded winding, quite common where I live. Your company probably could have bought a transformer.
agree, and before that on 3 phase diagram it is 208*30* 3^(1/2), but it should'nt be 3^(1/2), becouse 208 is already 120*3^(1/2), so u should'nt multiplying voltage between lines. Thats pretty big mistakes for person who lecturing about electrotechnics matters.
So thats why a neutral is not necessary? The leg that is perpendicular would make the system balanced. Is this correct? If yes ten the ground only serves as a safty
I remember my EE professor from my undergraduate days filling three chalk boards with a beautiful derivation of WHY three phase power, why not 4, 5 or n phase power? Answer: Because three phases was the minimum number of phases whose average power was a constant. Additional phases require additional windings and transformers, so go with THREE phases for the most efficient power grid. Beautiful. How I wish I had a video of his derivation. Even after over forty years as a now semi-retired Electrical Engineer who dealt with RF systems (FM broadcast, TV broadcast, and microwave), it was masterful derivation.
Wow good testimony. Can you mentor someone? I am an electrical engineer
@@theachebes5724 Not on 60 Hz AC power. My AC power/motors experience ended with college. My experience is in RF-- its propagation, and also loss/gain calculations for hight power radio and TV stations. Did several 5 MW ERP/60 to 80 kW TPO analog TV designs, but with digital the maximum allowable ERP is just 1 MW, so TPO's are typically in the 40 to 50 kW range. Still, it's 6-inch rigid coax line to handle the power. No more waveguide transmission lines, given that UHF TV now stops at Channel 36 (605 MHz) instead of Channel 69 (803 MHz).
i'm ee undergrad student, can i get your contact?
most stupid explanation
120V/240V "residential" power comes from a single 240V phase supply line produced from a step-down transformer (secondary side). The primary side of the transformer is fed by one phase (1 of the 3 phases) from the substation (commonly 12kV). The secondary side of the transformer is stepped down to a 240V SINGLE phase output. Because the secondary of the transformer is split into two halves with the neutral (or ground) at the middle of the transformer's secondary winding, two 120V reference-to-ground signals are produced. So there are 3 wires coming from the secondary of that transformer, (2 hot--1 wire on each end of the winding, 1 neutral/ground wire tap at the middle of the winding). Measuring the voltage potential from each hot wire to the neutral wire yields 120V. Measuring the potential difference from one end of the winding to the other end yields 240V (ie. 120V + 120V...actually, 120V minus a negative 120V). This configuration is also called a split-phase system. I added this comment because at 8:00 of this video, it's not clear enough, because it says "it's 2 single phase lines". Technically, it's one phase split into two halves and the waveforms are "out of phase" only because they are referenced to ground at the middle of the transformer winding.
I understand all that 100%. What I can't understand is how is there not live power on the neutral?
@@fuckjewtube69 here’s my understanding, take it for educational purposes, not instructional or safety purposes: the neutral wire DOES carry current, specifically the returning current through the home’s loads (ie. lightbulbs, tv’s, appliances, etc…). The neutral wires coming from the loads in a home’s breaker panel are tied to ground and the neutral wire coming from the secondary transformer is also tied to ground at the pole. Because neutrals are tied to ground, the Voltage potential from the neutral wire to ground is minimal. Power can be calculated by multiplying Voltage by the current (Amps). If there is practically 0 volts on a wire, then the power is going to be ~0 as well. **That is why it is possible for a person standing on the ground to touch a home’s bare neutral wire without getting shocked. It is also why the neutral wire coming from the pole transformer into a home is a bare conductor (no insulation). **If there are situations like lost/disconnected neutrals or grounds; ground faults where limbs of a tree touch bare high voltage wires; etc… then this statement may not always be true, it may be possible to get shocked. In summary, it’s about completing a path for current to flow, but also how much force (aka Voltage) behind the current flow; and it depends on exactly what two points in the electrical loop/circuit are being touched/connected in order to cause current to flow.
Great explanation of three phase. My son is entering the generation field and this will surely help him better understand three phase vs single phase. Me, 30+ years in hydro generation, so sometimes Dads explanations might be a little over whelming. Thanks.
Best explanation of 3 phase power I have come across. Currently I am an apprentice electrician.
This begins with faulty description of the effect of the north pole of a magnet rotating by a fixed linear conductor. Electrons do not flow towards the north pole of the magnet. According to Lenz's Law, the electrons in the conductor flow in such a direction as to oppose the motion of the passing north pole. That means that as the north pole approaches the end of the linear conductor, the electrons flow in such a way as to create a north pole at its end. As the north pole passes and receded from the conductor, the electron reverse their flow so as to produce a south pole at its end, to attract the receding pole. Lenz's Law is really a consequence of Faraday's Law of Induction, which states in mathematical terms that the direction the induced magnetic field is always opposite to the direction in which the magnetic field is increasing. The electrons in the conduction flow in the direction required to produce that opposing field. In the mathematical expression, the negative sign is what Lenz's Law expresses in words.
Absolutely, good point. I saw the same wrong explanation in other videos about AC...
Boring!
You are a true educator, not only do you make it understandable, you also create the desire to learn more, many thanks
The conductors between a voltage source and a load are called lines, and the voltage between any two lines is called line voltage. The voltage measured between any line and neutral is called phase voltage. For example, for a 208/120 volt service, the line voltage is 208 Volts, and the phase voltage is 120 Volts.(9:32)
EU:
230VAC => Phase voltage
400VAC => Line voltage.
This is the best explanation of phases current I came across 🙌🏾. The clock analogy made it so easy to stick it in. Thank you, you are a blessing 🙌🏾 ❤
I've was only wondering about 3 phase for about 25 years now, thank you.
Is there a Grammer error? I have was??? Think you for your advice
Say that again in English
@@enyakang6950 Yes. He meant "I was only wondering about 3 phase for about 25 years ..." but another way of saying it would be "I've only been wondering about ...". So he probably started one way then switched to the other without noticing.
As you probably noticed, the "only" is ironic, because 25 years is really a very long time to wonder about something. Only been wondering for 25 years!
I've been wondering for longer, as I'm probably older and it's a long time since I first heard the term.
as an EE I want this video to be tough in colleges, it explains it perfectly , I want to go back to college, who would not want to be in college -all you have to do i study nothing else lol kids these days have it made with the internet, this is a great video, I watched it twice because its so well done, who ever did the animation I want them to do my power point stuff and make it like this
This is one of the best descriptions and explanations on the Internet. Thank you
Another, unmentioned, benefit of 3-phase power is that 3-phase AC induction motors are much simpler, not needing a shaded-pole device on the field windings or a special startup motor to get the principal motor started. A 2-phase AC induction motor, like an internal-combustion engine, can keep itself going but needs a separate device to get it started.
We don't use 2 phase. We use single phase, with 2 lines 180° apart.
Common misnomer.
True (sorta). It is actually 2 phases, but they are phase locked 180 degrees apart and we have access to the 2 hots and that center tap. So in reality, it is a combination of both single and double phase. Imagine if someone had 2 lines each 120V and each having a neutral center tapped to the same transformer's secondary winding. Next imagine if they could put say a 45 degree delay in one of those lines. Would it then still be single phase or 2 phase? If 2 phase, then you are saying that when 2 lines are 180 degrees apart it is single phase but is it really? Some people would agree and some would disagree.
Brightwriter also you can reverse direction on it
If the starter winding is out or the centrifugal switch is non-functional, you can hand-spin a single-phase motor and it will run both ways. We had a bench grinder with a failed "cent" switch that would have sent power to the start winding. I put a momentary-contact switch in the start circuit, and then at the moment I would turn on the grinder I would push the added switch until it got up to speed, and then let that switch go and all was well! It we didn't hit that switch the motor would howl and not turn. If I hand-spun the grinder wheel backward and then did the other steps before it stopped drifting backward it would run in the wrong direction! Also, if I am not mistaken, the 3-pase motor was invented first, and it was supposedly a battle to make an effective single-phase motor after that.
Been studying for an upcoming test and needed some refresher material. You explain the material beautifully. Definitely have a knack for explaining complex processes in a simplified manner.
Thanks for the professional breaking down of information to simple yet informative points. It's great to have instructors like you.
Very good very clear explanation, l have been looking at this stuff for years and for some reason for me it just takes one mind and l know......yippee....what a life ...does it ever puzzle you why we have to search for so long before we find the right answer ....why can't we get it straight away
4:18 Why did the electrons stop in lines 1 and 2 even with the magnet rotating?
@@mikeymcmikeface5599 i dont think it does becuz only one line will ever be perpendicular to the magnet every time it rotates while the other two will be parrallel to the magnet
Errata: At 0:40, the sine waves are 60 degrees apart, but they should be 120. Magnets do not attract or repulse electrons. Varying magnetic fields cause electrons to experience a perpendicular force, which is why you need coils in a generator and motor, straight wires would not work properly...
Simple , Easy , Concise , Thoughtful .
Thanks
thanks for this. I'm a recruiter and working with construction and 3 phase power is a huge plus for what I'm hiring for. Your videos do a great job explaining this to a layperson w/o the background.
you don't want a lay person without the background working on 3 phase, lol, lmfao, pmsl and ha ha. not unless you have a good Hoover to clean up the little pile of dust that will be left where he once stood 💥😵🌬💨👋
this is the best explanation I have watched so far
Practically all automotive alternators are three phase, when rectified, the ripple voltage was less that 8%, single phase is 100%, no need for huge capacitors. Ideal in plants when AC had to be converted to DC. Three phase motors were very efficient. Three phases 120 degrees apart inherently generated a rotating field, without capacitors so motors could be made much smaller. Wish we had three phase in our homes especially for air and refrigeration compressors and fans.
for people who might don't understand this comment but will understand after this reply:
1 phase ac motors are actually 2 phase, since 1 phase would be impossible to synchronize. in order to get 2 phase from 1 phase, you would need a capacitor
2 phase electricity has a sine wave with 90 degrees offset from the first
Super video. The detailed graphics and annotations are really helpful
This is one of the best explanations/animations I've seen.
Kevin Butler
Woow. This is absolutely superb explanation. But why have you switched off the save button
How do I turn the save button on?
You suggest that electrons are attracted / distracted by a magnetic field. That's wrong.
It's the changing magnetic field that causes an electric voltage in the coils.
Lenz law, basic electromagnetism.
The waveforms at 4:50 and 5:25 look totally different. Why is the first one asymmetrical, as if the waves are grouped together? Just a crappy animation?
9 out of 10 comments are praising this video's claptrap. Unbelievable.
I was thinking the same thing. Anyways, most modern three phase industrial motors are induction and controlled by some kind of VFD.
@@joshbachman7706 indeed Industrial inverter drives are brilliant for matching speed matching ramps or current limit I have fitted thousands from 0.05kW up to 3000kW fun days.
At trade school 40 years ago we studied the GM delcotron alternator.. the study materials called it the six sweeps of the alternator... which btw are all three phase... great video!
Thank you. This is the first explanation that has made it clear to me
Of all the videos I have watched regarding 3 phase power this is the best one. Thank you.
Nice job. Working as an EE in the power field for 40+ years its always been easy for me to understand but difficult to explain to laymen....especially on a napkin with a pen.
😊
Unfortunately this doesn't show a very good representation or explanation of how an AC generator moves electrons around, but there are a number of other good concepts in the video that help explain the basics of AC power.
Electrons need a loop of wire to move around, and if that were shown (and it has to be in a specific orientation), we'd see that electrons move both towards and away from a magnetic pole in an AC circuit. If it were as simple as saying electrons were attracted to a "+" or "-" as in a DC circuit, they wouldn't be able to move around the loop at all. A better explanation is that the magnetic forces of a north pole push electrons in one direction around a loop and a south pole pushes them in the other direction. In between poles the magnetic forces are near zero so the electrons stop. Further, electrons only move in a changing magnetic field so the magnetic poles have to always be moving or the wires themselves have to be moving. In a large generator magnets rotate (spin) horizontally inside stationary coils made of copper bars that run vertically and the electrons move up or down in the bars depending on whether a north or south pole is acting on them. They also move perpendicular to both the magnetic field and direction of rotation (see Flemings Right Hand Rule for Generators).
Scott J
Electrons do not necessarily need a wire to move about. Electrostatic charge is one example. Electron beam is another. Old CRT TVs used the steered electron beam for half a century. There are scan converters that still use them today. Then there is always radio. Electrons are not pushed anywhere. They are lured to an electron depleted field through what ever means they can. Open space requires very high potential levels, metal conductors very little. This is a small sample of what you left out of your educated reply.
Bryan St.Martin, Although everything you've said is true, it's irrelevant to the understanding of 3-phase power and the functioning of electric motors.
The current in an antenna is negligible compared to the current in an electric motor, generator, or transformer where the electrical circuit is complete.
I do agree with Scott J that the pictures in this video demonstrating the magnet and the current in the wire are a bit wonky. The video makes it appear that electrons are attracted to the north pole of a magnet, and repelled from the south pole. If this were true, we could obtain free energy by using magnets instead of batteries.
Rather it's the moving magnetic field that induces a force on the electrons. Neither the pictures, nor the explanation in this video explain this, and in fact imply that this is not true. For someone who doesn't understand these things and who is trying to learn, this is going to cause a lot of confusion.
There's a reason he said at the beginning of the video that this video requires an understanding of how AC power works, and that if you don't have such an understanding you should watch the video on AC power first.
You're criticising this video for something that was explicitly stated would not be in the video. It's like someone saying they are going to show you how to cook pasta, and you're complaining that they skipped over how stovetops work.
Jeffery Wells, I'm criticizing the video because what he's showing is not only confusing, it's wrong. The north pole of a magnet does NOT attract electrons. The wires have to be moving perpendicular to the magnetic flux lines in order for there to be a force on the electrons. The wire has to be oriented so that force is in a direction that causes current to travel through the wire. What is shown in this video will cause no current at all.
Scott, I'm the creator of the video. If you watch the first video, you'll see and hear where I say that while I SHOULD show a loop of wire (per your comment) BUT in order to keep things simple, I will only show half. The issues with creating these types of 7-10 minute videos are: what do I include and what do i cut; what analogies do I use to explain the basic concepts which are rarely well explained. I decided that showing a looping wire would be harder to visualize and animate. It would also open more esoteric topics. My goal was to explain the topic to people who didn't understand 3 phase.
सर आपका वीडियो बहुत बढ़िया और शिक्षाप्रद है. 3 फेज एसी को आपने अच्छी तरह से समझाया है.
That's exactly what I was taught in the apprenticeship classes at Davis Electric. We didn't have animated video available to us.
S
Did you ride dinosaurs to school?
Data centers, and other commercial and industrial buildings don't necessarily use 3 phase power because of less amperes; it is because 3 phase power provides a "more balanced system". Such buildings demand more power than dwellings even though dwellings are served with lower voltage power.
I hope that you can make a video using three phase graph to educate rookie electricians about the danger of letting the phase wires to touch each other in electrical wiring, as three phase wiring nowadays is more popular for domestic electrical wiring compared to single phase
Good vid. Memories refreshed
Awesome very instructive all the confusing that i had for my whole life was cleared in your 10 minutes video
Thanks a lot!
ΑΡΣΕΝΗΚΟΛΗΘΗΛΑ ΠΡΟΣΟΧΗ ΤΗΣ ΔΙΑΣΤΑΡΟΣΗΣ
Altough the information in this video is completely correct, still one question was not answered: why 3 phases? why not 2, 4, 5, 6? why 3? And there is ONE major reason why 3 phase power is the way to go and the reason is the same why 1, 2, 4 phase power sucks. 5 phase power supply would have been the next choice. why? because power output over time is constant with 3, 5, 6, 7, 9 and so on phases (uneven numbers and any nmultiples of those)
th-cam.com/video/HqZtptHnC2I/w-d-xo.html
yeah.. that video doesn't explain anything, because the numbers seem to be chosen arbitrarily. so.. no real background there. again: after 3 phase power the next possible number of phases would have been 5 for the reason of a steady power output. but it can be explained quite easy why 3 phases were the way to go - there is no need for a 4 minute long explaination.
Hace mas de 100 años, en los inicios de la electricidad, se probaron sistemas de varias fases, pero el sistema que venció a los demás fué el trifásico.
Here's a simple answer - the cost of copper. The detailed answer is a very technical analysis of cost of additional copper for each phase versus the increased "performance" of more phases.
the need for an alternating current with constant power output (and not any sin-wave power!) came from electric locomotives. they would slip with a power peak coming for example from a single-phase sin-wave power. when slipping, the friction reduces a lot limiting the capibilities of it! but with a constant power output the trains could be built smaller and more efficient.
and again: 3 phases, 5 phases, 6 phases, 7, 9, 10, 11, 12, 13, 14, 15, ..(any uneven and multiples of those uneven numbers mentioned before) have a constant power output over time. and obviously when they all do the trick why use more than 3 phases? wouldn't have made sense in any way (yes, cost, but also complexicity).
always think of the histrory of the technical system you have in front of you and electricity wasn't always for wide public use! then tesla and westinghouse had their stupid fight over AC vs DC is was already decided in europe to use 3 phase AC. that's what noone from the north-american continent seems to know and maybe they just don't want to know..?
By far one of the best videos explaining three phase power.
What about 3 lines carrying 120 Volts each? Is there more than 208 Volts being supplied in that circuit?
Voltage is a potential difference between two points. It doesn't make sense to say that a line carries 120 volts. You need to state the configuration precisely.
You have made it so easy to understand. You're such great teacher 👍👍👍👍
Nice quality video. Let’s see what else you’ve got.
good video the way the narrator tries to go slowly through the material to make sure it gels and gets absorbed. Sadly at this point in time there are 333 dislikes meaning there are 333 confused people out there still scratching their heads with a bewildered look on their faces.
Thank you for this very detail video.
very simple and very good explanation as i have ever seen.keep going..........
the real reasons for three-phase are:
firstly that it is impossible to manufacture a high power single-phase alternator (see Leblanc's theorem and the theory of rotating magnetic fields, so-called reverse magnetic fields in a single-phase alternator are disastrous), an alternator of more than a few kva is necessarily polyphase.
secondly it is possible to transport more power on a balanced three-phase line (same current in all three phases) with the same amount of copper as with a single-phase line, this is a basic demonstration in electrical engineering training.
for three-phase motors, three phases are sufficient to generate a rotating magnetic field of constant amplitude and constant speed of rotation (proportional to frequency, Ferraris theorem). The mechanical torque of these motors is not affected by the sinusoidal shape of the power supply.
6- or 12-phase networks have sometimes been used to fabricate rectified direct current with low ripple residue.
Super analytical & graphical explanation 👍
Thanks for sharing your knowledge very informative, it inspired me to focus more making electrical video
Most enlightening video
One of the best explaination and illustration ive heard. Very clear. Thanks a bunch!
At 4:48 the wave forms are not 120˚ apart. I thought that you did not understand. Later on you make it clear that you do. I knew that 3 phase had something to do with generator layout. You made that clear.
Best explanation of 3 phase.
Thank you about explanation on Three phase. It's really good. Congratulations!
It's just how the AC power is transmitted, it's 120 degrees out of phase from each other. The magnet is the generator that is generating the power i.e. Hydro-electric Turbine at a Dam.
You are correct, but in most cases the generator is moved with burned fuel.
Thanks for the video. First of yours I have seen and subscribed while watching. Very informative.
I don't understand the 10.8kVA calculation. I get how each pair gives 208V x 30A. But why do you multiply by 1.732 again to get the total power for three pairs? Why not multiply by three?
there are such things as magnetic influance
If you look at each individual leg, you have 120V X 30 A = 3600W, then you can multiply by 3 and get 10800 W total, but taking each 2 leg pair and multiplying by 3 doesn't work because each of the 3 legs, A, B, and C is shared in 2 pairs (A to B, B to C, and C to A) and thus, each leg cannot devote its total power to each of the 2 pairs it is simultaneously powering. There has to be a derating for sharing the lines and when the calculus of the RMS sinusoid wave form is done that all these overlapping sinusoid wave forms come from (it's been years and calculus escapes me now), there are definite integrals that solve down to the square root of 3 as the deciding factor to multiply by.
You can multiply by 3 but then you have to use the phase voltage 120 V. The power you get is same whether you connect to star or delta. It is just simpler to understand the star connection as you can essentially for get the phase angles and view it as three 120 V circuits so 3x the power.
When a capacitor goes bad, you can start the motor by rotating it. Since 3 phrase always has a flow of energy, no cap necessary.
Capacitors are only used in a single phase motor to create an artificial phase
Had to watch 9 mins to find out why a data center would want 3 phase power. But hey, it's cool, I learned something along the way.
I had trouble understanding 3 phase but i instantly understood what you were saying & why ac asalates
Ths explanation for 3-phase power has to be easier than a 10 minute video. I still have absolutely no idea how this works.
Like my old teacher was saying: a motor is the same as a transformer, except that voltage ratio is one and the secondary is rotating.
Thanks for this great explanation.
I was hoping he would talk about how the Utility people go about routing Three Phase power through a town, versus how they go about routing more ordinary 220vac Single Phase power around a town.
A few mistakes in this video regarding the magnetic field and calculating the 3-phase power @9:14
What do you think the mistake was?
Apparant power calculation formula(only magnitude) is correct
@@moulies2600 - dude he already explained the phase portion at the start of the video
@@alparker7686 multiplying by 1.732 twice, in the power calculation.
Mistake in 9:18 !! 2x1.732?
Brilliantly explained. Thank you!
The windings of a 3 phase generator are 120 degrees apart. It would seem reasonable that the power coming from a 3 phase generator would reflect the 120 degree locations of the generator windings. It would be an interesting experiment to wind a generator with the coils located at different degree locations and observe the phase pattern
david
I read a paper on 5 phase systems a decade or two back. Very interesting, and extremely smooth operating. Imagine building a Bridge Rectifier for that. Tremendous torque.
Bryan St.Martin can you give me the name or the link of that paper
Very good explanation
Great video!
GREAT Explaining in simply terms. (inventor)
Best explanation ever.....Great work
Good video! Dude sounds like a calm Ray Romano
Thanks for your explanation
Thanks brother I appreciate your help with this knowledge I'm said from Zanziber in Tanzania how can you please help me with this knowledge
Sir any video on phase sequence and
detailed discussion on Star and delta connection in Power Transformer
An excellent explanation! Thank you!
Explanation is quite good enough but the rotating magnetic field is generated after current passes we should not place magnet before to understand this that makes it complicated.
Thank you for using kVA instead of Watts! It drives me nuts when I see people trying to use ohms law for DC circuits, in an AC circuit.
roy yung- great point but hey at the end its all in "P" ie power
You can use ohms law if the load is pure resistive and power factor is 1
Id be one of those people but it's hard to avoid the brainwashing terminology of the ac power fans. Hot neutral and earth? Isn't it power, ground, and redundant ground? Also wouldn't a pulsing DC run a transformer just the same? I mean unless ignition coils are some sort of black magic.
There is always a real component (I.e watts) in power calculation of AC circuits. Apparent power includes the real and imaginary vectors in the calculation and units is VA. Most electricians widely misuse these units and how to calculate them.
"Positive and negative phase don't cancel" Meaning the AC frequency is non destructive? I'm not 100% sure what you meant, could you clarify? Plus and minus should offset eachother.
Really one of the best explanation but what is r3 ??
The _radical symbol_ *√* is NOT an "r"-it is a mathematic symbol.
*√3* means _the square root of 3._ Or, _3 to the power of_ ½.
*√3 ≈ 1.7320508075688772935274463415059*
All of these 3 phase power videos should be titled "3 phase power for people who never took trigonometry"
If you don’t understand trigonometry, you just have to accept that you multiply 120 by the square root of 3, or 1.732, to get 208. Trigonometry tells you why. The why may be useful sometimes.
Outstanding!
Excellent video
Most of the negative comments are dealing in symantics While they may be correct technically the method of showing the process is successful. Besides, who gets thier electrical engineering degree from youtube videos? Chill tf out. Nobody's gonna get killed because the video didn't follow every rule of science in the illustration.
very helpful... always wondered about 3-phase
I remember those days when physics teacher in 8 grade was going through this and not many of us paid attention but I should.
Almost all of my higher voltage "Data Center" equipment (Printers, CISC based CPU and HD Racks) required 240v as standard. When we relocated and the power company could only supply 208v to our facility we had to have the manufacturer come out and make adjustments to operate on the reduced voltage. At least now I think I understand where the 208v came from, but why is 240v 3 phase standard for so much of the older, heavier equipment and household appliances such as stoves and dryers?
Because there was/is a common configuration that is 120V to ground on 2 legs with a stinger leg which is 208V to ground. They are 240 delta with a center grounded winding, quite common where I live. Your company probably could have bought a transformer.
Very well.explained .thank u
In the end of the video you said that In single line is 208 v *30 amps =6kva it’s wrong , the right is , in single line 120 * 30 amps
agree, and before that on 3 phase diagram it is 208*30* 3^(1/2), but it should'nt be 3^(1/2), becouse 208 is already 120*3^(1/2), so u should'nt multiplying voltage between lines. Thats pretty big mistakes for person who lecturing about electrotechnics matters.
very educative. Thank you regards
Great analysis
Great explaination!
Is there a video showing what happens when one of three phases goes away?
I've always been curious where 208v came from and this helped. Where does the sqrt(3) come from?
Cleared and satisfied
this must be how the flux capacitor worked on Back to the Future!
Let me correct you. It runs on banana peels and stale beer.
best explanation ever
I understood it yet didn't understand it. Lol I was always was curious about 3 phase. More power.
Fascinating. Thank you.
LoVE It!! Thank you for sharing you knowledge and explaining it well
Would have been better without the crappy distracting music!
I gave up at 1:44. He doesn't have a clue how fluctuating magnetic fields induce an electric current.
@@-danR could you explain what's wrong? I'm not be facetious, I'd genuinely like to know what was wrong.
So thats why a neutral is not necessary? The leg that is perpendicular would make the system balanced. Is this correct? If yes ten the ground only serves as a safty
thank you so much i loved everything yet i still have a question, how does the delta 3 phases works? and what is the diffrence between these two ?
Two is clean
so is the combined output modulating or are the phases so closely synchronized it remains steady?
LOVE THE CHANNEL YESS.