Three-Phase Power Explained
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- Опубліковано 14 бер 2018
- www.raritan.com/
This video will take a close look at three-phase power and explain how it works. Three-phase power can be defined as the common method of alternating current power generation, transmission, and distribution. It is a type of polyphase system, and is the most common method used by electric grids worldwide to transfer power.
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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.
Best explanation of 3 phase power I have come across. Currently I am an apprentice electrician.
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.
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!
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.
Thanks for the professional breaking down of information to simple yet informative points. It's great to have instructors like you.
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.
You are a true educator, not only do you make it understandable, you also create the desire to learn more, many thanks
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...
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 one of the best descriptions and explanations on the Internet. Thank you
Of all the videos I have watched regarding 3 phase power this is the best one. Thank you.
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
Super video. The detailed graphics and annotations are really helpful
Simple , Easy , Concise , Thoughtful .
Thanks
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!
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?
Thanks for the video. First of yours I have seen and subscribed while watching. Very informative.
By far one of the best videos explaining three phase power.
Thank you for this very detail video.
Thank you. This is the first explanation that has made it clear to me
Brilliantly explained. Thank you!
One of the best explaination and illustration ive heard. Very clear. Thanks a bunch!
this is the best explanation I have watched so far
Engineering Mindset is perhaps the best channel for this kind of stuff. This is also a good explanation.
Super analytical & graphical explanation 👍
Good vid. Memories refreshed
सर आपका वीडियो बहुत बढ़िया और शिक्षाप्रद है. 3 फेज एसी को आपने अच्छी तरह से समझाया है.
very simple and very good explanation as i have ever seen.keep going..........
Thank you about explanation on Three phase. It's really good. Congratulations!
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
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.
very helpful... always wondered about 3-phase
Best explanation ever.....Great work
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
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.
An excellent explanation! Thank you!
Thanks for sharing your knowledge very informative, it inspired me to focus more making electrical video
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 💥😵🌬💨👋
Thanks for this great explanation.
Most enlightening 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.
😊
Nice quality video. Let’s see what else you’ve got.
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?
Good video! Dude sounds like a calm Ray Romano
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 have made it so easy to understand. You're such great teacher 👍👍👍👍
Best explanation of 3 phase.
Great explaination!
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
GREAT Explaining in simply terms. (inventor)
Very good explanation
Fascinating. Thank you.
Great video!
Excellent video
Very well.explained .thank u
Great analysis
Outstanding!
very educative. Thank you regards
Great job, keep up
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.
LOVE THE CHANNEL YESS.
Nice explains. Thanks regards
I had trouble understanding 3 phase but i instantly understood what you were saying & why ac asalates
Great Video..
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.
Very good, thank you.
I've always been curious where 208v came from and this helped. Where does the sqrt(3) come from?
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.
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.
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.
you talked about other videos to watch but they don't seem to be available on the website or youtube , how do you get access to these ?
Very nice & useful
What about 3 lines carrying 120 Volts each? Is there more than 208 Volts being supplied in that circuit?
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.
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
best explanation ever
Thank you.
Ths explanation for 3-phase power has to be easier than a 10 minute video. I still have absolutely no idea how this works.
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
Excellent
Mr.Raritan
Thank you so much
Your video is one of the most excellent explanation animation videos again I greatly appreciate your video
I would like to upload animation videos
Of synchronize rotating machines induction motors, Generators
I hope so look forward to hearing from you
Thanks again
so is the combined output modulating or are the phases so closely synchronized it remains steady?
Good job
i get some knowledge about 3 phase.tq
Thank you
WONDERFUL
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)
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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..?
good explain....
Sir any video on phase sequence and
detailed discussion on Star and delta connection in Power Transformer
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.
Nice explanation. Like it...
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Cleared and satisfied
Please explain 12 phase used in electroplating.
Superb !
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
I understood it yet didn't understand it. Lol I was always was curious about 3 phase. More power.
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.
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.
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.