Why 3 Phase Power? Why not 6 or 12?
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- Опубликовано: 5 фев 2025
- Power Transmission Engineer Lionel Barthold Explains how 3 phase, 6 phase, and 12 phase power works, advantages, disavantages, and hopes for the future. Rotating phases, form an anisotropic tube. He worked on experimental 6 and 12 phase power lines at his company Power Technologies, Inc. before it was sold to Siemens after a long successful career. The experimental polyphase lines were located in Malta, New York, not far from company headquarters in Schenectady.
Lionel Barthold is 104 years old today and still kicking. Mr. Barthold, Wishing you good health and a long life !
Engineering has always been about resolving what can be done vs. what can be done economically.
That was what I was thinking as I was watching the video. How much more expensive and complex it would be to double everything. Miles and miles of extra wire, plus all of the breakers, transformers etc. Three phase is already very expensive. Six phase would practically take an act of Congress to get it anywhere. Only heavy industry could ever afford it.
@@bekimbal9658 In some places, particularly California, the cost isn't putting stuff in. The cost is the environmental, zoning, not-in-my backyard lawsuits it takes to put anything in. In many places, you have the cost of buying the right-of-way and maintaining it. These remain constant regardless of how many wires you put in. Then you have the cost of the energy lost due to inefficiency. That's why technologies like HVDC and superconducting transmission lines are being deployed. The moral of the story is considering costs isn't about installation or capital costs, it's lifecycle costs.
@@straightpipediesel Wow! Thanks for the info. I am glad I don't live in California. If I had a lot of capital and wanted to locate a business, I don't think California would ever make the list.
What can be done economically, legally, ethically, environmentally friendly. Unfortunately we have some people (Republicans) who care only about the economics and the rest be damned.
@@mattfoley6082 three phase vs six phase has nothing to do with politics. And most engineering projects often get tripped up by costs. Just not in the way you think.
This is how I sound to my parents when I explain how I set up their Netflix
Damn that’s funny
😂😂😂
So funny
@Hungarian OK. We're friends now. Now what??
This had me wheezing
3AM and I'm awake learning about power supply and transmission. I have no control of my life.
snap.....
HektorbajsmanIII it's 5 am for me
2.11am here. ;-)
9PM for me. Well I work overnights and got to be at work in couple hours. Usually I am sleeping right now until 10 35PM before I gotta be at work.
no control? don't let it phase you ;) HAH * bad joke ik, I'll go uninstall youtube
I like how older people speak in a considered way. People now days decide what they want to say beforehand and speak the words in a fast and ‘detached’ manner. This bloke is running it through his head and commentating. This gives the listener the correct time to follow closely to what is being said.
You don’t notice it till you hear an older, intelligent person speak.
Whenever an elderly gentleman talks about something he knows a lot about, it's always interesting. Be it 3 phase power, war or factory work...
this is why we must ensure knowledge is never lost, share it!
or squirrel 2:48
....or the crazy guy wasting hours of my employees time talking about breeding betta fish when I worked at petsmart.
I like the conservation of his emotional energy. Say what's most important, without any fluff or ego.
What is he saying that is nonsense? Stfu
Thank you for the clear, practical explanation. As a mechanical engineer who has always been interested in electrical engineering, I have certainly learnt something today.
- Channel is named after Edison
- Talks about alternating current
The irony
Tesla > Edison
Marcus Tornea
Do your snide remarks apply to other fields?
Can Ford detail the benefits of torsen differentials? Or turbo power?
Was Ford activelly trying to destroy people who came with better inventions? No he didn't. Edison on the other hand was a complete cunt against AC.
yeah take a day off ferrous bueller!
Just as ironic is that TESLA, the car, runs on DC Power.
I have been an electrical engineer in the electric utility industry for 30 years. I am convinced of two things, technologically. 1) If you can dream it, it can very likely be done. It's usually just a matter of time and money. 2) The most amazing thing about the electric grid: It WORKS!! Of all the little in-series things that can go wrong, the fact that people have, at their very fingertips, a virtually endless supply of electrical power for THEIR convenience is utterly astonishing!!
I would give this man a hug. He taught me a lot scientifically with one story told in a conversational format
One important property of 3 phase power is that the power delivery across a section is constant therefore a motor torque is constant.
Very close to constant. Why reinvent the wheel. 3-phase has worked well for over 100 years.
It's nice to see these recordings of the greats that were there when standards were being worked out.
It's great to think that there's whole groups of people just trying to improve every part of the world all the time.
An important thing is glossed over here with 6 phase. We can construct special air core transformers whereby the phases can be put into high mutual inductance circumstances using spirals and tuned for series resonance whereby the contribution made by a centrally acting phase will be repelling the magnetic fields created by the two outer phases in mutual induction, thereby increasing the volume of magnetic fields issued outwards from polar areas for an increased efficiency of amp turns/ field.
Fantastic, I wish I could have had lecturers like this guy when I was at college.
he is awful at explaining.
the function of college is NOT to educate, its function is to INDOCTRINATE !!!!
This guy would put you into a coma.
They do have 6 9 and even yes 12 phase systems, but they are generally for use in near immediate conversion to DC mainly for extremely high current applications like electroplating and aluminum smelting. They are carried as bundles of 3 phase sets and each set is offet by 1/3 of wave timing from the next set.
A prominent example in recent times is 6 phase ev motors. Both Ford in their race-only SuperVan and Koenigsegg in their commercial Gemera used six phase motors to a scary effect
Wow, love how nonchalantly this guy completely blew my mind, and yet still I finished the video understanding why we don’t use more than three phases for power transmission. Although I still don’t understand what he was saying in the beginning about voltage of a six phase system.
Answer: /watch?v=MnH_ifcRJq4
It is highly useful in the application of rectifiers since the the higher the pulses the further offset the harmonics will be which makes complying with THD limits a bit easier. You can achieve this though by branching the 3 phase power with one set going into rectifier directly and another going through a transformer with a phase shift before going into the rectifier to get 6 pulse.
He talks with a lot of conviction,. It is pleasant watch a video where someone like this gentleman talks with conviction about the subject. Great video.
Lionel Barthold, you are a perfect example of why it's important to get a good education....you can explain the answer to this complex question simply, yet intelligently and understandable.....thank you sir.....
Six or Twelve phases are created from Three phase supplies using special transformers. These have been used to feed multi MW rectifiers such as those used by older electric railways.
When I was in engineering school my professor explained it a little differently. DC power requires two conductors. Three phase power is P=sqrt(3)VIpf. That square root of three factor is the key. For a 50% increase in the number of conductors, you get a 73% increase in the amount of power that can be transmitted. That only works for a three phase system.
Even in my engineering my prof explained in a similar way.. Which i dont remenbet exactly.
Excuse me sqrt of 3 is for the balance supply so it doesnt have to be sqrt of 3 thats just the factor
Cabron Sliver if you go through the development of power capacity you will that the what is inside the square root is directly related to the number of conductors. It is not a supply balance factor.
i worked in the power supply industry for most of my life. A lot of military equipment runs on 3 phase 400HZ, we used to regularly wind the transformers with a delta and star secondaries so we could feed them into a 6 phase rectifier stack. That reduced the size of the output capacitor and in some case let us do away with the capacitor.
iam electronics technician for 15 yrs and i appreciate his theory, basically electronics is from electricity.........thanks giving another hints of my minds about basic in electricity.
It only took about 15 years to finally learn this. Great vid.
Why the power do not doble with the number of phases ?
Is it just the efficiency wich drop ?
why ?
michaelovitch I have the same question.
Please someone explain it to me too.
diminishing returns in power transmission is very similar to that of Yagi antenna design. After the first 3 elements, the gain by adding more elements (4,5,6...) become substantially less than the gain of the first 3 elements. So the best compromise between # of elements and size/cost/gain (especially with large antennas), is to limit it to 3 elements.
Some early comments on this video suggest 6 and 12 phase systems are not practicable because it would be difficult to build six phase motors and distribution systems and similar. However, the intent of phase orders above three is for transmission only, and in particular higher power density in a given right-of-way. A high phase order bulk transmission grid could be built or developed over time, but all evaluations of high phase order that I am aware of were point to point transmission lines with conversion to three-phase at each end via transformers.
Thank you. From looking at the logic of 6 phase +, it didn't make sense why it wasn't implemented. This video explains why perfectly.
Tried this once. As soon as we went to warp it blew out half the plasma conduits and it took weeks to rebuild the anti-matter injectors. The ship was adrift around Neptune for a week. Star Fleet was furious!
...or so the Romulans would have us believe.
We've got something going here. You repliers are a very large cut above the typical YT reply legions.
🧐🧐🧐❤️❤️❤️🇬🇧🇬🇧🇬🇧😂😂😂😂👍🏻👍🏻👍🏻🤝🤝🤝💪🏻💪🏻💪🏻🤣🤣🤣
As long as we stay near neptune. There have been reported sightings of a high number of Klingons around Uranus. ;-)
Trev0r98
Romulans love David Hasselhoff.
The power of a phase goes up and down at twice the rate of the frequency of the alternating current.
With three phase three powers are out of phase and the sum is a constant.
So single phase power produces power in a device that is modulating. And you can hear the hum and feel the vibration.
With three phase power the power in the device is constant and not modulating. So the only hum is due to the imperfections of the device.
dsrekjw say it again with more simple words please!
The explanation is really simple: three is the minimum amount of points to represent a vector in two dimensions. As rotational movement is in two dimensions you need three phases.
If you wanted to move a ball in three dimensions you would need four phases (forming a three sided base pyramid)
@@nirodper you made it even more complicated
3 phase devices humm too. Just stand next to a transformer. The hum is due to magnetostriction and its frequency is either 50 or 60 Hz.
I just want to sit in this guy's living room, drink decaf coffee with him and just listen for hours.
And smoke a fatty:).
Sky - decaf aint gonna help keep you awake.
i wish i could still sit with my grandfather, talk and also record it
I have sat with one of his ilk. We were doing a project on monitoring induced currents from Aurora on the Fairbanks to Anchorage inter-tie . Professor Bob Merritt, RIP. The point regarding additional breakers at the sub-station is only the beginning. The switching for capacitors to achieve the R Factor due to predominant inductive loads would certainly be interesting. That is only a drop in the bucket.....
You lost me at decaf
I actually indirectly lost a job over this topic. The little boy above me (at a high end primary voltage switch house manufacturer) was always mumbling about inventing "four phase". Finally one night, in front of everyone mind you, I taught about how two, four and hypothetically twelve phase had already been tried and how three phase has the best efficiency and other optimal parameters for our AC grid... Pissed the little boy off, he was a horrible electrician anyways. I posed a threat it seemed. Was fired the next day. Thank you for the lecture/Video.
fla playa I think I met the guy. Wasn't it him who said that when a fuse blew it was because it pulled too much power?
jgstargazer May have been. This guy would ask you to lift him up and rotate him, as he grabbed a hold to change that fuse.
The New Zealand Railways Department had 3 phase to 12 phase transformers feeding twin pumpless steel tank Mercury arc rectifiers for the 1600V DC suburban rail service in Wellington. They were being replaced in the 1980s with 6 phase bridge connected solid state rectifiers.
Great walkthrough of the constraints and trade offs involved.
The real reason we use 3 phase is Star Dalta!
This gives two different voltages dependant on configuration. If you go 6 or 12 phase you are basically doubling up on your 3 phase with no additional benefit! When you factor in the skin effect in HV transmission it becomes even more apparent!
Star Delta ..... If you generate 3 phases and connect your load across each phase (Delta)..(like a motor) you get a voltage (415V in the UK) but if you take those same lines and connect your load from one of the 3 to a central point (star) you then get 240V (in the UK)! As an addad bonus you get reduced neutral sized cables because when you get multiples of 3 single pahases the power flows not just back to the star point at the transformer in the substation but allong the neutral and back through the adjacent loads to the other 2 phases! In effect if you have a well ballanced system you can loose the neutral connection at the substation completely and not even notice! Obviously this is an oversimplification as the star point is not only connected to neutral but grounded to Earth!
Skin effect .... To transmit power over a distance you raise the voltage to high levels (you get the same volt drop but it is now a smaller % of the total) the electricity flows not throughout the cable but concentrateds in the outer skin. If you look at a Pylon the cables are not single cores but usually 4 bunched together giving a greater effective area and allowing cooling!
6 or 12 phase ...... Unless you generate a separate multi phase you are simply adding multiple parallel paths. this does not get you a great deal of benefit! If you generate multi phase you have problems in how you connest a star point as you will get different voltages with relation to each other. If you want to visualise this draw a set of 3 points forming an equalatral triangle with another point in the middle. Measure the distance between the points and you have your voltage (4.15 cm/ inches between points gets you 2.5 cm / inches to the center) Now draw your extra phases and note you can no longer get the same measurements between all outer points!
Sorry for prattling on but when you know it becomes realy apparent there is only one good way to do it ;0)
A great reply which took me 1/10th of the time to read as to watch the video.
240/415 UK ??? We had 220/380 on the european continent, but that was decades ago. As far as I know, both have 230/400 now.
@@ronaldonmg It is the same ratio .... just a different starting voltage! Europe is now 230v ;0)
Short and sweet it is more cost effective with 3 phase conductors ! End of story !
Actually no, it's most cost effective today with no phases--DC. Why China's transmission grid is being built as DC. His idea might have been useful if the electronics used to convert to and from DC hadn't been dramatically improved.
@@straightpipediesel Note the keyword "more" cost effective. And AC is generally still cheaper over shorter distances.
i haven't understood from the video, so that means if taking aside complexity and economic problems, 6/12 phase would be better than 3 phase, right? or it doesn't provide any benefit?
Naturally there are competing factors. It would have been more interesting if he started with just one phase, and explained why two or three were better. I imagine it's a combination of generators working better with multiple phases, wiring being more efficient (shared ground?), and industrial loads like big motors working better with multiple phases.
@@straightpipediesel only for long distances
My ex went through 12 phases between coffees
LMFAO 😁
john woodworth lol
Another winning reply. You guys out there must be practical, practicing, shrinks.
@Ryan Plethra As often, your reply to John W. went to me, John L. Sorry. (But I do appreciate the different takes on divorce. My take was a release of 20-years worth of tension headaches, tho I didn't realize it until the gavel was banged.) Cheers, JL
feeling great to hear about it from the person who actually did this by himself
Our old dairy farm was three phase. Had idea what three phase was until we had one of the barn re-wired and one of the electricians explained it to me. The place had a zillion pumps and electric motors and was a maintenance nightmare. Glad to have sold it.
To answer the question. It take 2 wires to carry a single phase. but it only take 3 wires to carry 3 phases. in essences. by adding just one more wire(50% more capacity.) , you have tripled the amount of power you can now carry. To put it another way. For the same given "total" psychical wire size, 3 phase carries twice the power then a single phase does. to go from 3 phases to six would require twice the wires and only give you twice the power capacity, thus "No gain".
For 3 Phase versus Single Phase It is actually 50% more cost (in wire, insulators and switching) gives 3 times the capacity or a 200% increase.
You miss the point. If you have limited ROW and need more power, you can effectively intersperse a second three-phase line with the first one to get the doubling of power without a new ROW or adding ROW width for a second three-phase line.
Too bad you did not make this video because you answer the questions he fails to answer. Thank You
Yeah - but you STILL need a 4th wire for ground.
What is "psychical wire size"!??
This is electrical engineering. I thought that the 3 phases is convenient for driving electrical motors. 2 phases , each on the opposite side of the shaft can not tell a motor which way to start spinning because the equal torque force is on both clockwise direction and counter clockwise direction. 3 magnets 3 phases allows deterministic spin direction.
You misunderstand what 2-phase means. "2 phases, each on the opposite side of the shaft" is actually single-phase - a 180 degree phase shift is just the opposite polarity of a sinusoid. Two-phase power has phases 90 degrees apart. Most single-phase motors start by using a capacitance to generate a second phase during startup.
The main reason for the popularity of 3-phase power is that if you balance the loads on the phases, you don't need a return "neutral" line, so you only need three wires. This doesn't work for 2-phase - you still need three wires.
The thought exercise here is, "If 3 phases is more efficient, more powerful, and just better... why not more phases?"
@@BrightBlueJim ... how do they go about balancing the loads? So, if you have 3 phase power connected to a 3 phase motor, you would have a balanced load, correct? I'm gonna have to study balanced loads until it makes more sense...
@@truthbebold4009 A 3-phase motor is always a balanced load. It has the same number of turns on each of the windings, and each winding is powering the motor for part of the time. Rotor inertia helps ensure that the load is spread over all of the phases, even if the mechanical load is higher in some shaft positions than others. I only mentioned balanced load because if you run a building on 3-phase power, many of your loads are single-phase, so they're not automatically balanced. You have to design the building wiring such that there will be approximately the same amount of load on each phase, or you end up wasting money because of the extra copper you're not really using. Three phase power, when designed to use the same amount of power on each phase, saves copper cost, because single phase loads are wired from one phase to another, and all of the current from one phase returns on another. So there is no need for a neutral wire.
Its cutting the distribution loss in half that makes 3Φ power desirable. 3Φ power is the smallest number of phases that create a virtual ground removing half of the the resistance (aka copper) loss incurred distributing the power. The phasor sum of equal load currents from all 3 phases to ground cancels out and there is no net ground current. 1Φ clearly has a hot and a ground. 2Φ at 180° still requires the current to travel both out and back for 2-way round trip copper loss. Its more plainly equivalent to 1Φ hot-ground when you realize "ground" is an arbitrary designation so choosing 1 of the 2 as ground or physically connecting one of them to ground return to a simple hot-ground 1Φ system again. 2Φ at 90° requires a 3rd wire to be ground but only a fraction of the balanced load current cancels at the ground terminal. But since it need 3 wires you can drive all 3 wires 120° offset and cancel a;; the ground current instead and deliver more power with the same installation cost. Any number of phases 3 or greater can be used to cancel out each other's ground current out. but a number greater than 3 provides no additional benefit, it only increases the cost of wiring and equipment.
A 3Φ induction motor can start and run at the line frequency, but as noted a 1Φ induction motor that runs at the line frequency doesn't have any average torque starting from 0RPM and may randomly spin up in either direction unless something is added to split the phase to create starting torque. For fractional horsepower motors the cost of 3 windings and building wiring isn't justified and torque is created by splitting the single phase electrically with another winding at an offset angle either as a coil (split phase motor) or a capacitor (capacitor split phase aka permanent split capacitor or psc motor) in series with the main winding or by creating torque magnetically using the wider soread of the high stalled rotor magnetic flux with a shorted turn (shaded pole) to create a net torque . The electrical phase splitting can be combined with a starting switch to disconnect the starting winding after the motor starts. It can be as simple as a positive temperatur coefficient resistor (used for small refrigerators and A/C) or timer relay (most typically used one-size-fits-all repair part) a centrifugal switch on the motor shaft (for low lifetime start count applications) or a relay that opens when either the start winding current falls below a specific value or the voltage rises above a specific value. There are also 1Φ induction motors that also use a reduced excitation of the extra winding to achieve a higher running torque. Sometimes they use the same basic scheme, e.g. the CSCR capacitor start capacitor run motor, or different schemes like the CSIR capacitor start induction run motor that connects the start winding and a series capacitor in parallel with the main winding to start and switches to run by removing the capacitor putting uses the two windings in series.
After building a few RC cars I gotta I've become interested in AC and DC electronics so stuff like this makes me geek out... lol. I should have went to school for EE. Electricity is mind blowing.
Wow. A direct, honest, and respectable comment. You rock.
I am a 33 year Electrician. We have 3 phase power because it works well, and that is what got established first.
The breakers for three phase must be properly adjusted in order, not random as most two phase panels are, all of them in residential areas. The load balancing necessary for all three phases is critical. It would be a constant resetting of the adjusters of breakers depending on the varying hour to hour and day to day changes in load, both for the end user and for the utilities... This one reason why three phase is used for commercial use, not residential. Transmission lines are a different case.
very simply yes, more "straws" and more power can flow, but Tesla found that you could use minimal copper to distribute using particularly 3 conductors. apparently "creating a complex electrical spiral down the line, who's analysis really boggles the mind, particularly in transient cases. Steinmetz attempted to crack it and backed off from it" ( Eric Dollard: Anti-Relativity)
2:48 SQUIRREL!!!!
*bark*
OHMYGOCAN'TYOUSEEIT'SASQUIRREL?
*bark bark*
YOUREALLYDON'TUNDERSTANDTHEWEIGHTOFTHISSITUATION!
*bark bark bark*
ASQUIRREL!!!
*barkbarkbarkbarkbark*
when the guy is too boring and you se a squirrel
2:49. Thanks.
haha! good observation.
i would say lizard
reminds me of my grandfather, amazing blend of knowledge and wisdom
2:35 - almost after the video is over, now you're introducing the guy. genius.
Lionel Barthold and the other geniuses at PTI (Paul DeMello and Don Ewart to name a few) have pioneered electrical transmission for us all. We stand on the shoulders of Giants....
I will use this at bedtime to help me sleep.
This video's presenter is a carbon copy of the lecturer who taught this subject when I was at University. Besides looking the same, they shared a knack for repeating points and making many hand gestures but never really understanding which concepts were easy/hard or answering the right question. I agree, the subject of electrical power transmission makes a good sleep aid!
That's not economically efficient.
Although I liked this explanation, I have to say that I laughed out loud at your comment.
im sure its a very effective tool!
Its dry subject may be, had one interesting instructor for Pwr. Trans. course but he hardly ever taught the subject matter!
I did that when we built the Tokamac Fusion test reactor power supply. Lawrence Berkeley Lab 1979
What happened then?
3-phase transmission lines are the most efficient for the following reason. Single phase lines require 2 conductors, or 2 conductors per phase. 3 phase delta requires 3 conductors, or 1 conductor per phase. 4 phase delta would require 4 conductors (etc.), which is also 1 conductor per phase, but requires more conductors due to additional phases. Wye arrangements would add a conductor, requiring (#phases +1)/#phases conductors.
This is a very interesting discussion, presented in a rather understandable manner.
It’s amazing how few people had ever heard about Tesla in the 1970s when I was in high school. Very few books about him then. Now THE WORLD knows. I’m not sure when that all turned around or exactly how but I’m certainly glad it did.
This video was uploaded in 2011, I wonder how the old man is doing right now. Is he still alive?
Got this recommendation just when i have to wake up from my bed
Mizhidor - I wonder if you would have gotten the same recommendation if you had to wake up from your floor. Or if you didn't just wake up at all. Hmm
@@onekerri1 I do occasionally wake up from the floor
yup. probably more useful for educational instruction than practical use
Right. EE education starts at DC (remember PIEs and EIRs?), then moves on to AC in the 2nd semester.
I was really wondering why not 6 or 12 recently. This is great!
The answer is simple, it's the smallest number of phases that gives motion on a specific direction. As soon as you add more phases, the cost of transmission becomes progressively more complex and expensive for no real gain.
his gentle voice lulls me into trance, I find myself writing large donation checks to PTI
More phases means smoother rectification, and such.
This is a program you should watch if you're having trouble sleeping.
That voice. This guy could explain quantum mechanics to me and not only would I understand it but enjoy learning it too.
Who the hell does he sound like? Its like hes narrated a movie or something I've seen before.
How beautiful! I love great engineers and scientists who are appropriately humble.
Please help shreekanthadpad@gmail.com
A three phase rotating electric field is enough to start any 3 phase electrical motor into rotation. That is why Tesla settled on 3 phases. It is simpler, more cost effective, and most importantly it was enough.
The power of 3,6,9 as he always said. It would make a triangle. A triangle is the simplest geometric shape that can house a perfect circle/most efficient angular wave pattern. So think of it as this. Why would I make a 6 sided shape to house a circle when I can do it with 3?
No one has wronged Tesla, most people from US put too much emphasis on Tesla and don't care about the other greats of the time including Dobrovolsky (Russian working in Germany), Oskar Von Miller (Germany), Galileo Ferraris (Italy), etc. US based media puts too much emphasis on both Tesla and Edison because they are North America based inventors. This is a gross oversimplification of history. Edison and Tesla are where you can start learning, please move on and learn more.
EdisonTechCenter Edison was a chancer though... Tesla did everything by mathematical proof. Hence the current wars.
I get a kick out of how there's a bunch of Tesla fan boys in here. I mean- WTF, who is still upset about Tesla. Really?
This what I was expecting to hear in this video! If I remember correctly after 3 phases the transmitted power per kg of conducting material stays the same.
What do you mean by "higher order systems"? I can see that the rectified signal will have double of quadruple harmonic frequencies. Is this what you mean?
Edison was a visionary, he invented so many things that we take for granted today, however his D.C. [direct current] had limited uses and could not extend very far because of the line losses involved with DC. There would have to be a power generating station on every city block in a high population area. Tesla had it right with alternating current and xformers.
People like this are amazingly creative - they think beyond the box
Simply put and very informative.
Excellent sir...Simple but superb....
the more phases, the more coils - so smoother motor speed control, weaker traction power
In the last 70 years there are no motors that would benefit from smother controls. Maybe in a confined system like a nuclear submarine but never in industry or domestic usages.
i was a lineman for an electric co. for 40yrs so this is an interesting topic for me. although i'm getting old and starting to forget how much i knew.
Thank you. It is always great to watch a video with so much depth.
What does he mean by "the voltage per foot is the same" for 6 phase?
+Enigma758 The voltage you can obtain per foot of conductor theoretically of course will remain the same
+Enigma758 He's talking about the voltage difference between the different wires. So if you look at two of the wires in the three phase line and they're 3 feet apart with a voltage difference of 120,000 volts, and then you put a wire between them it would be 1 1/2 feet from each of them and have a voltage difference of 60,000 volts from each of them so either way you have 40,000 volts per foot across the air gap between the conductors. Since the gap needed between the wires is determined by their voltage difference, this means that you don't have to move the original 3 phase wires any further apart to add the 3 offset phases to make 6 phase, so the suspended bundle of wires would take up the same space, but carry almost twice as much power.
jasexavier this is an excellent explanation. Thanks
But why 'almost' twice as much power? Why not *exactly* twice as much?
Power loss to heat.
This should be called TeslaTechCenter! Edison had no clue about AC, be it 1, 3 or any other phase.
It is a myth that edison did not research AC as an engineer.
No. Edison stole everything from others - just like Apple & Jobs.
That's the myth, Mikey.
@@mikeymcmikeface5599: And you were there watching! That's awesome. What did he do with "everything"?
Agreed! he was too busy electrocuting elephants and dogs to try to prove DC superior. Ironically, DC of the same voltage potential is more dangerous because Dc has no zero crossing
Material cost would be doubled for 6 phase and quadrupled for 12 xD
Thank you, thank you, thank you for taking the time to share this insightful video with us. You're a good man Mr. Barthold.
"Taking the time"? Yeah, he sure did that!
I am an EE major and every electrical class I take is purely math or code. The professors never really sit down and talk about the "why" part..
He didn't give the answers I was expecting. The main advantage of 3 phase power over single phase is that it can transmit more power per unit conductor weight and with the same insulators, though DC still beats 3 phase. Another big reason is that a 3-phase load can draw constant power throughout the cycle while a single-phase load has to flywheel through no power twice per cycle.
***** Say what?
Notice the interleaving of the second three-phase line with the first, and of the second six-phase line with the first six-phase line. The benefit is very high power levels on an incredibly compact ac line.
***** Is it any more compact than DC?
ApolloWasReal As I recall, an equivalent six phase line can be much shorter than an HVDC line and somewhat narrower. Ground clearances are quite modest because the line-to-ground voltage is relatively low for the amount of power handled. The larger number of conductors may make an HPO line equally or more visible in spite of its modest stature.
***** Interesting. Let's see... assuming a phase-neutral voltage of 1V and a 6-way wye (asterisk?) load with a 1 ohm resistor from each phase to neutral there would be no neutral current and the total power would be 6W. The power per phase conductor would be 1W, same as 3-phase.
One difference is that the voltage between adjacent phases (A-B, B-C, etc) is only 1V. Non-adjacent, non-antipodal phases (A-C, A-E, B-D, etc) are 120 deg apart so the voltage between them is the same as the 3-phase phase-phase voltage: sqrt(3) = 1.732V. And opposite phases (A-D, B-E, C-F) are 180 deg apart so the voltage between them is 2V. Not sure what practical effect this has on an aerial line where the phase-to-neutral voltage that dictates the amount of insulation required. So for all practical purposes this is just two 3-phase circuits, with a higher voltage between some of the conductors than you'd see in 3-phase, and twice as many transformer windings. But the lower voltage between adjacent phases might allow more compact buried cable designs.
I'd have to model it, but the electric and magnetic fields at medium distance from a 6-phase aerial line might be lower than a 3-phase line carrying the same power. That would decrease losses. But it would still have inductive and capacitive losses that are completely absent in a DC line.
I'm up at 2:00 a.m. and can't put the phone down from learning
That's good, but, on the other hand, I hate to see an inquisitive mind wasted by staring into a little bitty screen.
switch it off amigo
, Excellent explanation, three divisible by six, twelve, eighteen, ask Tesla.
So basically it's possible and it works but the management of the transfer equipment gets way harder and more expensive. Interesting. Thanks for the info!
This is very easily understood. If the phase number belongs to 3*2^x you can just put them in the stator of the generator like you did on 0:48. However in this status you generates twice the power but also the resistance torque on the rotor is doubled as well. Energy doesn't appear out of nowhere. More than 6 phases would make the stator clumsy and rarely offers any more benefits (remember the resistance is there, if it's heavy then it won't rotate that fast!) so 6 is best. Get the phase shifter to couple them back to 3 phase and it's ready to go.
For sending powers sake a 3 phase compared to a 2 phase sends 3x the power (it equalizes itself so no neutral line) at 1.5x wires. It's efficient. Odd time phase numbers such as 5 or 7 does NOT offer more power per wire thus useless.
Tesla is the father of polyphase. Edison was stuck on direct current.
You are absolutely right.
You don't get 'stuck' on direct current, you get stuck on alternating current. Pedantic, I know :D
Dennis S the problem with ac is the skin effect. you see, tesla hadn't forseen this. neighter edisson. but at high power/high frequency there is such thing as a skin effect...where in the electron flow is not going trough the entire conductor, they flow trough the outher edges of the conductor...thus the skin effect.
nuclear power plant output stations send the power to the natuonal power distribution grid via tubes, pipes...
thats why..in the near future, where electric vehicles are foreseen, dc main distribution lines make more sense, also dc does not have inductance and capacitance losses.
ihavecojones - the bus bars I install are kidney shaped.
Actually it's not a problem, and Tesla made use of the effect in his demonstrations. He also tried to get a deal with some Natural Gas companies to use their copper pipes to conduct alternating current as well as gas. The gas companies were scares of sparks and refused.
Thanks, now I watched the whole video again to see the squirrel :P
161 people still want to shove a knife into an electrical receptacle.
In catscan and xray imaging we use 12 phase to create a more consitant power Source so when we expose an electron cloud to the rotating disc usually made of tungsten we get a closer amount of alpha beta radiation for a specific technique set by the technologist so it still varies by what we input but its not underpowered or overpowered
6 phase was quite popular in high power transmitter design using valve rectification because the ripple frequency after rectification was six times the supply frequency, compared to 3 times that of a 3 phase circuit, and the ripple voltage was reduced by a factor of.250/.057 from that of a 3 phase rectifier. Harmonics were also much reduced. This made for simpler smoothing circuits in the conversion to dc.
God bless the playback speed setting on RUclips
toffolotty What, so you can slow it down to learn more quickly?
Holy crap. 0.5x made me instantly shitfaced drunk watching this. Fantastic.
The irony of three-phase being explained in a Edison named channel ...
Tesla is rolling over in his grave.
The reason why his idea never got used is because electronic conversion to DC got a lot more efficient. Instead of 6 and 12 phase, we are now using HVDC transmission, or zero phase. So Edison did win.
Your channel should be called Tesla Tech Center. Edison was a hack.
Edison was ultimately partially right. DC is more efficient at transmission than 3phase or 12phase etc AC. That's why it the only solution for long distance underground, submarine cable, and ultra long distance transmission. Its vastly more efficient. You would never consider 4,6 or more phases because DC would be the way to go.
@@WilliamJones-Halibut-vq1fs In what universe. You believe in some strange physics.
Insulation is dependent on the DC or peak AC voltage to earth ground. Current loss is dependent on wire size. Although AC current rises and falls AC loss is equivalent to the RMS current value in DC amps assuming a resistive load. If you add more phases you approach the DC value for insulation. However the current is still dependent on wire size. The big advantage to AC power transmission is the ability to easily change the current/voltage ratio with transformer. High voltage insulation (mostly air) is much cheaper than huge current capacity wires. Since power is measured as current times voltage and the biggest loss is due to the current traveling in the wire and not the insulation loss the higher the transmission voltage the lower the power lost in transmission. Three phase powers main advantage is the ability to use induction motors which do not need brushes and slip rings or commutators.
The main advantage to DC transmission is had when sending long distance power underwater or underground. Here you must take safety into account and use what amounts to a large coaxial cable. To send three phase power you would need three of those type of cables or a specially built cable with three very high voltage insulated conductors inside.
The disadvantage of DC transmission comes when you need to change the current/voltage ratio you then must change back to AC so you can use a transformer plus the most efficient way to make large amounts of electrical power is with alternators not DC generators or with batteries.
@@kimobrien. Oh, a communist. You must love murder.
@Richard Vaughn There is a significant loss in charging and discharging capacitors at higher frequencies in the dielectric material. The load current in the DC line will change when you turn it back into AC. You can try and minimize that effect with a big capacitor in parallel and inductor in series or a gigantic battery. So now your back to the original problem which was the line impedance. To turn that DC back to AC you need to build a very big inverter which will also have losses not to mention the creation of switching harmonics. To make the DC you also need to switch the AC input and if you want the line voltage not to vary you also need to use a combination of inductors in series and capacitors in parallel or a gigantic battery.
Problems with inductive loads don't disappear just because you have a long distance DC line.
They had problems with underwater telegraph cables between the US and England because of capacitance. However in that case your trying to send square not sine waves plus you have a big capacitance due to the closeness of the conductors.
There are multiphase power transport systems used. Also ultra high voltage direct current transport systems seems to be effective in undersea cables when we transport power on levels between 100 000V and 500 000V.
Wow! Correct sir, it would have been a High Voltage Technician's nightmare switching 6, 12, 24 phases. But very intriguing!
seems that he still did not explain why 3 phases...Why not 2 phases?
+Jiayang Ruan efficiency and practical. Considering the cost and space required, more phases become impractical. 2 phase isn't as sufficient as 3 phase and again it's a more cost effective way of supplying power with the least amount of power drop between the phases.
what do you mean by power drop?
Personally I thought the reason is that, 3 phase can generate smooth rotating magnetic filed as in ac motors, whereas two phases can only generate pulsating field. This is the essential reason :)
Additionally, three phase system is simpler than two phases. Three phase uses three wires; a two phase system needs four, not two
So I guess a mix between efficiency and practicality.
davidpar2, or 3 wires may work making one of the wire common. just make one wire thicker, since they would be 90 degrees apart.
Squirrel was best part of the video, I think its name was Tesla.
Nah, Chuck Testa.
I am an uneducated Japanese of humble means so what I am about to say is something what has been said by someone else many times. I cannot help myself leaving this remark because I think Edison was adamantly opposed to AC generations and transmission. Yet, this technology is being explained by an institution which bears his name.
Nikola Tesla was the real genius
***** Yes, traditionally DC lines must be very long to be competitive. However, DC is finding a second home in underwater transmission and via cables into congested areas (AC becomes difficult and impractical when cables must be longer than a few tens of miles).
Patrick Legacy One of the magnetic units is named after him.
***** I think it is not easy to explain to 13 year old school children why AC transmission underwater is inefficient. I have a nephew at that age, and I don't have an answer which he can understand or appreciate. We don't teach capacitance and inductance at junior high schools.
tnakai1971jp Heh. It's not easy to explain this even to some experienced electric power engineers! One has to get into "imaginary power" (reactive power) generated by the cables that must be extracted from the ac cable at distances of not much more than about 15 miles. On land the shunt reactors to do this are messy but not difficult. Underwater substations, even small ones with just a shunt reactor in them, are highly problematic. Short underwater cables are doable though even there the reactive current flowing from the capacitance of the cables to the ends of the cable tend to use much of the thermal capability of the cable unless the cable is very short.
The history of power systems is a treasure of knowledge.
Excellent explanation about Polyphase power supplies. Rather than this, new machines have gained importance such as Five phase machines, Six phase, 12 phase machines. Please explain some of such machines sir