How Three Phase Electricity works – The basics explained

How Three Phase Electricity works – The basics explained


hey there guys Paul here from the
engineering mindset .com in this video we’re going to be looking at Three phase
electricity and this follows on from our series on Electrical Engineering so if
you haven’t watched the previous videos on this so far then please do this first
links are in the video description below coming up we’re going to be looking at
how a simple AC generator works then we’ll look at a single phase power then
two phase power and then finally three phase power as well as how three phase
power is used and why also while we don’t use four five six phase etc power
so first of all let’s start with a simple AC generator we’ll start with a
single phase to understand what’s happening and then we’ll add in other
phases until we get two three phases let’s take a copper wire and wrap it
into two coils and then place these coils or perceive each other within a
stator and connect the ends together to create a complete circuit now if we
place a magnet in between these coils and we start to rotate the magnet then
the magnetic field will disturb the free electrons within the copper wire and an
electrical current will begin to flow we’ve covered how the free electrons
flow in a previous video on the electricity basics so please check that
out if you’ve not done so already links are in the video description below as
the magnet rotates so does the polarity of the magnetic field as you can see in
the illustration the North and South Pole of the magnet are rotating and as
they rotate they pass across the coils which force electrons to move notice the
lines of the magnetic field are in these oval shapes on each side and they meet
through the central axis of the magnet you can think of these as one side being
positive and the other side being negative and in between these overalls
the magnetic field is neutral you can see that the intensity of the magnetic
field increases on either side until the center where it is at is maximum
strength and then it decreases again until it gets back to the neutral point
so as this field rotates through the coil the coil will experience an
increasing intensity of the magnetic cause positive half and during this
increase the free electrons within the copper coil will be pushed and begin to
move faster and faster in one direction up until it reaches the maximum point of
the magnetic field then as the magnetic field decreases the flow of electrons
will begin to slow all the way until it reaches a neutral point where no
electrons will flow then comes a negative side of the magnetic field and
as this passes through it’s going to pull the free electrons backwards the
game the flow of electrons will flow faster and faster up until the maximum
point of the magnetic field and then it will decrease back to the neutral point
this is why AC electricity is called alternating current because the current
of electrons alternates in direction backwards and forwards just like the
tide of the sea if we were to plot on the graph the speed of the electrons
flowing during the rotation then we would get a sine wave pattern in this
sine wave you can see that the electrons are stationary at the start in the
neutral zone and then the speed increases through the positive half all
the way up to the maximum and then it begins to decrease all the way back down
to the neutral where no electrons will flow again after this comes a negative
half where the electrons speed up to the maximum point and then they begin to
slow down again until the magnet has completed one full rotation where this
will then repeat this complete rotation is known as a cycle and the number of
cycles per second is called the frequency which is measured in Hertz
you’ve probably seen 50 Hertz or 60 Hertz written on your electrical goods
this means that the generator of the power station is completing a full
rotation either 50 or 60 times per second so the direction of the current
is therefore also changing 50 or 60 tones per second also when it is written
on electrical products this is just telling the user what type of
electricity the product should be connected to now coming back to the sine
wave that we saw earlier this product of current also represents power and if we
connect a lamp into the circuit we’ll see that it will increase in brightness
all the way to the peak that maximum point then it decreases in brightness
all the way down until the neutral point where the lamp is actually
off because no current is flowing but then it will increase in brightness
again as a negative half of the cycle comes fruit and the electrons start to
flow back through in the opposite direction and tell again it reaches the
neutral point so at these points in the cycle the lamp is not producing any
light and at these points in the cycle the lamp is not very bright so it’s not
of much use so if you’re working in a room and this lighting is flickering
like this it’s going to get really annoying to improve this we can add
another set of coils or a second phase into the generator we can do this by
placing the coils a hundred and twenty degrees rotation from the first set of
coils and then connect this up to another lamp this rotation means that
the coils will experience the changing intensity of the magnetic field at
different points in time the first coil reaches maximum current and brightness
and as it decreases the second coil will begin to increase this has improved the
lighting for there’s still a gap which will cause a flicker so we can add in a
third set of coils or a third phase and this will mean that one of the lamps are
almost always at its maximum brightness so the lighting is nearly constant there
are still some small gaps between the phases and you could keep adding more
and more phases to fill these gaps but this will become more and more expensive
to keep running all these cables so three phase became widely accepted as it’s a
good compromise between power provided and cost to build now in the real world
you’re not going to use three different lamps on different phases to create
lighting the lamps in your homes are all on single phase but they are flickering
it’s just that they are turning on and off so fast that the human eye can’t see
it unless you record the lamp in slow motion a more practical application is
the power electrical induction motors and other commercial and industrial
equipment as three phase will provide a lot more power to these items meaning
you can pump water higher or you can run motors faster etc etc power is generally
generated and distributed in three phase and transformers are used to change the
voltage if you want to learn how transformers work we’ve also
covered that two links are in the video description below now one of the
interesting things with three phase power is that you can connect all three phases
and power large industrial equipment or you can also connect to only one of the
phases and also power small electrical goods this is generally how large tower
blocks and skyscrapers distribute electricity through the building the
lift motors and air conditioning pumps etc will need three-phase power but the
computers and office equipment will need single-phase power so they distribute
three phase power up the building and then draw off from this as needed the
same occurs with the distribution of electricity across a city houses will be
connected to only a single phase because they do not require much power whereas a
large building will be connected to a three phase supply as they will require a
lot of power okay guys that’s it for this video thank you very much for
watching I hope this has helped you and you’ve enjoyed it if so then please
don’t forget to Like subscribe and share this video and also follow us on
Facebook Twitter Google+ Instagram as well as our website the engineering
mindset com

100 thoughts on “How Three Phase Electricity works – The basics explained

  1. IMPORTANT The magnetic field shown in the video is an overly simplified illustration to help visualise whats happening. This is not representative of the real world. If you need to dive deeper on how magnets and their fields work, please start with this wikipedia article: https://en.wikipedia.org/wiki/Magnetic_field
    IMPORTANT WHY DOES HE SAY "Free fasze" … because he has a regional British accent.

  2. Most private homes (in Scandinavia I must add as I don't know rest of Europe) have 3-phase drawn into the building. We largely use 3-phase for stoves and other appliances giving us the ability to have high energy consumers with low amperage main fuses, typically 16 amps*3.

  3. Can anyone explain to a moron (me) why an electric motor powered by AC decides to run in one direction rather than the other – or rather, doesn't try to turn in both directions alternately, changing its direction 50 or 60 or whatever times per second?

  4. Bro bro bro that's it ya that's it . All my life teachers said about 3phase is 120° and bla bla but it never understand how 120,3phase mean n lots more. But here u comes. U know what YouTube was recommending this video from a long time but I always ignored it bcz I know noone can explain better but i finally decided to watch n I m amazed i mean love u bro u r awesome explainer u cleared my doubts which noone could this way.
    I liked n subscribed u bro🤩

  5. "They are turning on and off so fast the human eye can't see it"
    Then i am not a human because i can definitely see it, i hate this generalization that humans can't see beyond 24, 30, 50, 60 Hz.

  6. Good explain and presantation against university educators who just memorized and do not know how easily it works

  7. I understand your explanation about using 3 phase generation to keep the AC power supply constant (as with your example of the light bulb in your video). However how does that explain residential lighting and equip such as tv’s, computers, etc. that are running off of single phase electric from a pole mounted 120/240 transformer? Is it because even with single phase power supply at 60 htz its still to fast for the eye to see?

  8. That was so well explained. Just wish I found this sooner. Now that I'm subscribed things should be easier. Thanks very much!

  9. A simple explanation that most everyone will understand. Where was this guy when I was learning about electricity in school? He explained it much more clearly in a couple of minutes than a bunch of long-winded lectures by "teachers" ever did.

  10. I'm an engineer working in manufacturing and work with electrical contractors a lot. This greatly helped clear up some concepts for me! The Engineering Mindset channel is awesome! I'm watching your other videos kinda binge watching. Great job explaining things in layman's terms!

  11. Thank you Paul! You make this complex and dangerous subject knowable and easier to grasp. Fantastic graphic animation; You are a teacher and instructor par excellante`

  12. Electricity was never one of my strong suits, and the extent of my knowledge of it was how to screw in a lightbulb. LOL. But after this video I feel like I have learned something, and am grateful for you explaining it in terms that I can grasp. Thank you.

  13. This is very intuitive. I never knew how an AC current is the way it is. I've read books and tried to researched, but got nothing. Congrats on making me understand the concepts of this whereas other sources could not.

  14. seems its serving secondary purpose now days as no one uses 3 phase motors from it , just advantage is load distribution in house and if one phase is weak then it can b switched to normal one . in out house we have just selector for phases .

  15. THANK YOU ! I get it now! so now i have a question… i have a wind generator that produces about 2.0 volts AC (yes two volts) and it is a 3 phase generator. so if combined that would give 6 volts correct? how could this be used to make 12 volts of DC current?

  16. I have a wish-list:
    1. That you had a means, less cumbersome than comments; to quiz the students to see how well they've grasped things so far;
    2. that a multi-channel oscilloscope could be configured to show each phase in color;
    3, that you covered power factor before going on the 3-phase power.

  17. hello very much from Colombia I would like a video that explains that electrons are made inside a coil so that it produces magnetism as well as the example of the bulbs that the electrons collide against the atoms and heat the filament I would like an example in the coils as I said previously thank you so it would help me to better understand the electronic and also repecto that is the magnetism and what phenomena have related to the electronic thanks are very good giving us good examples

  18. Great video, I would make one correction though. Most if not all houses in the US are wired with two phase. Most circuits only use a single phase, but for something heavy duty like an electric furnace, or electric cloths dryer, you would see a large plug and the appliance would be marked 220-240V

  19. Any chance I can just connect my brain to yours and get a whole data transfer sir? lol, I/we commoners appreciate you!

  20. Dude thank you so much. We had electrical engineering subject for a year and I never understood how 3 phase appliances work. Now when I am starting my own factory after all these years, I had to understand 3 phase power to understand functioning of my powerful induction motors. You did a greatr job! Thank you so much man 🙏

  21. Great video, though I do have a comment:

    It's stated that homes are usually supplied with 1-phase power, due to lower power needs.
    However, some places (like Northern Europe, where I live), homes are supplied with 3-phase power, even in a small flat. This is due to the fact that some home consumer, like stoves, require 3-phase power. So here power is supplied as 3-phase 400 V (previously 380 V) 50 hz., and different areas of the home is supplied by 1 of the 3 phases, whereas areas like the kitchen has an 3-phase 400 V outlet for the stove.
    I have also noticed that in areas like suburbs, local substations (transformers) supplies as many as 5 – 6 lines, each providing 3-phased 400 V 50 hz. , usually at up to 32 Amps per home.

  22. I'm blown away by the fact that someone gave this a thumbs down. The video was clear and well understood. The illustration was on point and very direct. What more can you ask for? Google should force people to leave a comment to say why this deserves a thumbs down.

  23. Ok this was a good video. But i have some questions. If electrons are moving back and forth with each rotation of the magnet, then surely the electrons' net movement is zero? It looks like the same electrons are moving back and forth through the same bit of wire.. this obviously isn't what is happening, but could someone explain what is?
    Also, this is a minor point but wouldn't the direction of current change 100 times per second at 50 Hz? Not 50 times per second? Because within one cycle the direction of current changes twice.

  24. Hey I have a question since lights are on single phase do the flicker more when it's a single phase generator or 3 phase and y ?

  25. 👉How 3 Phase electricity works: https://youtu.be/4oRT7PoXSS0 AND 👉Three Phase Electricity: https://youtu.be/4oRT7PoXSS0 are the same

  26. What… I had no idea this was a thing… now I'm going to keep my eye out for indicators… I'm guessing the big power lines are all in 3s and I just never thought about it… <excitement builds>

  27. One suggestion before I continue watching the video. You might want to remove the "jiggle" of the video title above the animation we are trying to concentrate on, it is a bit distracting. Thanks for sharing knowledge

  28. 6:00 Don’t lamps nowadays use capacitors so they work with single face and never fluctuate light?

  29. Ive searched for years to understsnd what three phase actually is and how it works. This, my good man, is the best explanation ive ever come across. Thank you so much.

  30. Question… Does the voltage increase with the number of phases? Meaning, One phase = 120 v, Two phase = 240 v, Three phase = 360 v.
    Or does the voltage remain the same?

  31. Premed physicis (among other courses) humbled me, and made me realize what an anencephalic monster I really AM!

  32. I honestly went to school for Instrumentation and Process Control. If your videos were played in a classroom setting, the institution could have crammed three semesters into two. Excellent video!

  33. Sometimes while I write something for a long time I begin to see how my lamp begins to flicker very fast, this makes me very nervous so I can’t continue my work

  34. I certainly learned what normally takes a whole semester in a college, just by watching this video. No really, this video did an EXCELLENT job with the narrating in sync with the illustrations. GREAT GOD above THANK YOU for Youtube Channel and Youtube!!! 😀

  35. Откуда может быть синусойда, если ротор делает круг…? График неправильно показан….

  36. Hi Engineering Mindset, apology if you included this in the video and I missed it – but did you cover "Why not more phases?" ? Also, I see there are 5 Phase motors out there – what do they do?

  37. Holy crap these videos are outstanding! I finally get it AND I have a better appreciation for electricians (not that I didn't before).

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