How three phase math works (277 + 277 = 480?)
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- Опубликовано: 29 сен 2024
- This is a quick run-through of how three-phase math works.
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I've been a licensed electrician for 15 years. Only recently have taken my career a lot more serious. Ive always root 3 277 to get explain the answer. But never actually spent enough time getting down to the real answer it just worked to get wire size or over current protection. It's cool to know the things others think they know but actually don't.
I am still confused why for B to get the x value is 277√(-120) and not 277√(120)... The signs have confused me more lol
PUNK'SnotDEAD the signs are only for rotation purposes from the origin. You must take the “magnitude” which is always a positive number.
What I found so far to make this easier, is to consider the 360◦ : 3 = 120◦ (phase shift) right?
So WHEN EVER YOU MEASURE FROM LINE TO LINE (PHASE TO PHASE) you use the square root of 3 and multiply the peak voltage. So 277V * (√3)=479.77807369V
It is the magic number that makes life so much easier.
ObsessionPC genius 😉
Which also works for 120 & 208 V
And with 220?
@@prontosolutions4370 that would be delta
very good..this is how it should have been explained
I suppose if you want to get technical or you really need to understand the math behind it, you can use all these details. But I hate math and love to simplify things to just the bare essentials. So I would probably say, you can’t simply add two voltages on different phases because they’re 120° out of phase, and thus are never equal at the same moment. For instance, when A is at 277, B is at 203.
To calculate the voltages you can just multiply or divide by the square root of three, 1.732.
120 * 1.732 = 208
480 / 1.732 = 277
here's what you do. 480 divide by 1.732 you get 277 . 120 multiply by 1.732 you get 208. The magic number is 1.732.
You're welcome
Well done! Thank you. I would show the 3 sine waves on a graph and show the voltages at various points from one sine wave to another.
Excellent! Love the short, but explanatory videos. I first learnt the 3 squared method, so it’s good to hear this put another way.
@All viewers. Skip to t=6:00 min and stop watching at t=6:26. That's the sum of a straight fwd subject... Root3..
Because of the particular angles involved, the square root of 3 can be derived easily from geometry without resorting to trig functions.
You cannot directly add phase voltages because they do not happen at the same time.
Well said
Not intended to upset you but if you really want to know if you are understood by your audience, write down every word exactly the way you sound on this video and let someone technical enough, a prospective student of yours, etc, read your words and see if he/she gets it. The way you present the material doesn't sound right to me. I went through the video with you, drew everything the way you did...and I came up with two pages of stuff. One of your viewers below, Obsessionpc's way of doing it took me ONE LINE. If science would be explain this efficient there would be no need for much (mainstream dogmatic) education as most everyone understands things well explained.
Explain it to a good high school student, and see if he gets it good enough to explain it back to someone else, and you evaluate the latter.
It seems to me that obsessionpc below has a far more efficient way to get the answer. You don't go about it the way Nikola Tesla would go, but the way Thomas Edison and mainstream science would, that is unnecessarily complicated.
People that are smarter than even myself? How smart are you really? What have you invented...achieved...Not much humility or modesty there, so you shouldn't say that, for your own sake...image...
Thank you for sharing though.
Jeremy Li dude seriously this guy is arrogant.
Next time, please write/type out the equations used. It would have been much easier to follow. Something simple like this:
(-1)*277 v*Cos(120°)=-239.8 v
(-1)*277 v*Sin(120°)=138.5 v
Note: (-1) is because the vector B's magnitude is in the opposite direction relative to vector A.
arm chair QUARTER BACK.. HIS WAY WAS EASIER
Congratulations.. Well explained. Thanks..
«Phase» is a confusing word. Electritians can mean:
1) A single voltage
2) A conductor
3) A phase angle
Problem is you never know what they are talking about.
Quiz of the day:
The generator is star connected. Each coil produces a single voltage of 132V , a phase?
The load is a boiler with three elements, delta connected. Each element receives one voltage of 23V. In Norway with their IT distribution system, they call ths a phase. But how can 132V at the generator be 230V at the customer? Phases? You never know.
Imagine two legs, pointing to opposite sides. It is 180°. Their cosines are one at both sides. It is full length, so 2 times 277.
Now lets lift both "legs" up by 30°. Cosine on both sides are now shorter. Cos 30° on one side, and cos 30° on the other.
277 x cos 30° + 277 x cos 30° = 479.7780736965.
Also, 2 x cos 30° = ✓3
My friend you can't teach something that you are confuse yourself. Has nothing to do with trig. But to the concept of direction and magnitud of a vector. Applied to the direction of the current on two phases.
“you probably think I’m smoking crack” “anybody see that fly flying around?” 👀
Love the video. I've always understood why it was 480V but never saw anyone prove it with the vector math. Thanks.
I love the internet! Thank you for a clear explanation!
this is the worst example of explaining three phase power. i am old school so....one has to know math, it is that simple. simple trig and how to use the sq root of 3....
Thanks for the refresher. It has been years since I first learned this. I am glad it still works! Haha
*The President of The United States of America Lives There: 480/0.3 = White House*
The Wye system is also known as the star system
GOD I remember figuring that stuff up. back in ET school
You can draw out the phasor diagrams and work out the trigonometry which reveals the square root of 3
5:42
@@kevinc9006
Just before 5:42 he stated that root 3 was derived by "people much smarter than [himself]". With no explanation as to how root 3 was originally derived.
1039sflem is stating how a person would derive the root 3 term (with phasor diagrams) that makes these calculations easier.
@@TRB94 too bad I was more worried about banging chicks, smoking pot, and snorting pills instead of listening to my math teacher. But my dad was smokin and snorting with me so I guess it ain't all my fault.
I tell you what though, I have been learning G Code on 3 axis CNC for the last month and that is pretty tricky. But once you get the hang of it it's not so bad just remember to calculate for the bit.
It’s hard to take electricians seriously when it comes them explaining math
can you please down load the fuse rating formula for 480 volts
how does that 277v know its 120degrees away from the other 277v?
Question: You're showing this on a diagram which makes it appear as though the physical displacement of wires being at 120 degrees is what causes the 480v, but would I be right in assuming it has nothing to do with the physical displacement but rather it being due to the 277v lines oscillating from 277v to 0 to -277v and back again, and so when we test one 277v line it will be at its peak while the other line we are testing will be 120 degrees out of phase of that 277v to 0 to -277v cycle?
I just posted your link to two of my Facebook pages. I think my friend's and coworkers will appreciate your style and method of explaining electrical systems. Most of the younger technicians seem eager to learn, yet lack the basic math skills they should have been taught in secondary schools. This may be due to lack of emphasis on real world problems these students will certainly face, or curriculums which shifted from math and science to social and less structure oriented subjects.
To the point being though, I can appreciate your time and effort spent compiling this series as well, I am sure, as many others who watch this series of videos. Hopefully you will find that your work here has paid off in ways you are not even comprehending yet.
One thing I always made reference to when questioned about how electricity worked was to say it (electricity), is the closest thing to true magic which exists in our physical realm. Clergy and electricians are much alike in that we both work with (for) something we never really see, yet can certainly feel. If we ask it to help us and obey the set rules, we are rewarded for our efforts. If we stray away from the laws we know we should strictly follow, then it is only a matter of time before we pay a penalty for our mistakes. When all goes as we planned, our FAITH tells us that everything is going to work and our work is done. So we tend to take more time to learn more, and try understanding this thing we cannot actually see, but trust it will allow us to manipulate for the good of our society and the needs of our structures we built.
Hopefully this makes a little sense. Thanks from an old crusty electrical/electronics guy here.
to mcheek27357
Very Basic math with practical application in schools should start even earlier .The problem is the the social oriented subjects are being modeled less at home in a practical interactive sense( i.e. In person with undivided attention...real face time!). Now the schools are mandated to take up the task as you referred to. At one time some very basic math and applied sciences were absorbed at home if you were mom or dads apprentice.Reading out loud was practiced a little in S.S. and at the supper table.
High school instructor RET.
Thanks, this was an awesome simple explanation.
Glad you enjoyed it!
Hi great videos thank you for posting them. I have a commercial heavy duty AC Delco diesel powered generator that has two sub panels built into it. The data plate says 120/208 3 phase. I would like to get 460 or 480 volt 3 phase for another motor I would like to power. I have not looked into the sub panels to see what,how, or if it is possible to reconnect this generator to create the higher voltage of 460 or 480. Do you know if this is possible and what to look for? Would a Series-wye = 480 volts. Would I need a 12 wire configuration to do this? Thank You for you time!
Thanks,This helps my campaign on how 2+2 does not equal 4
i get it sort of but, how can you use cosine and sine on this? thats only for right triangles..
Thank you so much for this video..kept asking my teachers how this worked ans they couldn't explain. I appreciate it 3 years later🙏🙏
Why is one phase positive 277 while the second one is negative 277? Why is the second phase negative?
This describes the actual back-and-forth motion of the electron flow in an AC system...in three-phase systems there are three ideal states: one flows positive direction, one flows negative direction and one is static...this is because of the actual, physical rotation of the turbine(generator) and the resultant rotating magnetic fields...also, this synchronous movement of the electrons in different directions is why they do not spark...it really is a finely-tuned and timed choreography of the actual electrons in motion...additionally, in this video he is using a Cartesian system whereby the first Phase(A) is horizontal in the positive direction(X) and no vertical(Y)...the second Phase (B) is located in the negative X direction, positive Y direction...the vector math is added and the Pythagorean Theorem FOR A RIGHT TRIANGLE[(X^2+Y^2)=C^2] gives the resultant vector(hypotenuse) as 480...hope this helps
Ignore the plus and minus signs. They don’t help.
This is very helpful. Thank you!
Question 3 phase 481 leg is
A 276
B 242
C 293
Awesome video, thank you!
Just take phase to phase and divide that by 1.73
thank you for this great video :)
Still need help send link I want to learn more of the long way
Can I get a link for vectors how to to where to start
To calculate the voltage between two phases in all three phase systems 277 ×* 1.75* = 480
how did you come up with 1.75?
Gabe Jaghnoun He rounded the number off. The real way is as in the video. The square root of 3 is 1.73205. You also use this number for all three phase calculations for VA or watts and to solve for amps. Hope this helps.
This helped me a lot thanks👍🏾
Cant find your website 🤷♂️
I am retired now, but I truly enjoyed working with three phase, wye and Delta configurations. Good presentation.
Thanks! I've always wondered how that works, I'll never be smart enough to do the math but at least I understand why the voltages don't add up.
Ryan McGinnis if I can figure it out so can you. Lol
Apart from the religious explanation, the videos by Eddie Woo are excellent for yr 11 and yr 12 maths.
Sqrt of 3 is derivable by using unit circle (assume phase voltage as 1)
5:42
4:43 Dude, if you *were* smoking crack, then you would've said that 277 plus 138.5 equals to a unicorn, and to the rest of the crack smoking community that would've made a perfect sense. Jokes aside, AWESOME video, thank you!
it's a triangle, two legs have a 120 angle! What you need to find is the hypotenuse or the long side.
You wonderful Canadian thank you
vector B is in the second quadrant so X is negative, Y is positive. how come you got +X,-Y in your calculations?
It's because I am using -120 and not 120 because of the instantaneous polarity. Vector A is +120 and then vector B is -120.
Clear and concise explanation. Thank you.
hi... have finished the 3 phase couse?
What if multiply by 1.732
Actually his diagram is wrong. A leads B and B leads C. B and C should be swapped.
Which diagram? Give the time, please.
That home generation sounds good.
Sorry but this makes no sense.
thanks , very helpful and appreciate it
wow. the smoking crack comment killed me. lol
Square root of 3? Vs root of 3?
Explai how to get the root 3 please
Please send me the vectoral link
Voltage between phases is tan(120°)*277 = 480V, or in Europe tan(120°)*220=380V
Are you a fruit?
Or are you an apple?
Although the magnitude is the same, tan(120°)*277 = negative 480, which for AC is 180° out of phase. When dealing with vectors, trigonometry and measurement units, the pacifics be important.
Otherwise, half vast answers mean you end up as an orange in the Atlantic wondering WTF?
Granted, if all 3-phases are rotated 180°, as occurs every 8.33 milliseconds in the U.S., and you're referring to root mean squared (RMS) values and not peak voltages (difference of square root of two), and you don't care about 208/120 or medium voltages common in distribution and industrial power, then your semi-representative numbers serve as marginally mediocre examples.
Phase shift between phases in symmetrical three-phase system is 120° (2π/3rad). From the vectors you can calculate that voltage between any two phases in three phase system is sqrt(3) bigger than voltage of one phase.
Somehow that all made sense to me, hehe
Great video, if I understand correctly, it's similar to walking to a friends house. 100 ft north then 108 ft east for a total distance of 208 ft. But as the crow flies it's only 120 ft. Is that anywhere close to what you're saying?
277*1.732=479.76 or 480V
Ok I get 208, 480 but not the 600
Very interesting thank you for posting
Where'd 347 come from?
Thanks very much SR
How do you clean up the power
5:29 "People who are much smarter than even myself" = people who paid attention to their trigonometry class in school. Law of cosines: c²=a²+b²−2ab⋅cos(180°-120°). With a=b(=277V) we get c²=a²(1+1-2cos(60°))=3a², so c=a√3.
Can one also explain this with 3 sinusoidal waves?
Those are the 3 sinusoidal waves that are 120° apart
Where does 460 come from?
Fuck Yeah!!! thanks man.
I see your point but from a school perspective JUST US SQUARE ROOT OF 3 ... SIMPLE
Where is the J notation? lol Or the root of 3 = 1.732. When we get old it is harder to do vector stuff.
You're smart.
what about 110 +110 = 220
Please why there is to polarities + and -??? why x is +277 and the other is -277? i watched all your trigonometry videos and i did understud that stuff completely this just doesent make any sense anymore.
Sort of like electricity in a mesh, only the mesh is always shifting and dragging the current with it. And it's invisible as well.
Let me ask you a question sir.
How can I solve this one? 32-6/(200/346)/(240/415). I have seen it on three phases sockets and pluger. Please help.thank you.
In the field, or on a test, for a quick calculation just multiply 277v by the square rot of three (1.732) = 480, or 120v times the square root of 3 = 208.
Really good video.. Appreciate your channel.
does this video even work???
Hi bit confused as to where you got 347 from near the end of the video to make the 600volts.. great video by the way and will look at your vectors and three phase as am doing electrics in French so have to redo alot via utube that I cannot fully comprehend in french language like the calculations albeit I am now having to go back and learn pythagorus therom dahhh! .
If you come from a math background you can always use law of sine/cosine to determine the hypotenuse or in this application, line to line voltage.
Hi there im currently attending an Electrical Apprenticeship and was wondering if you could share that email on adding vectors ?
Forget I asked
What did you ask? lol
@@TheElectricAcademy I asked how to get 480 volts out of 277 on three leads. Now that I heard the explanation, I'm more confused than ever before. Thankfully there's smarter people than me in the world to do the figuring.
"At this point you must think I'm smoking crack"
Me: Yeah!
Con Edison had a substation arc event yesterday and they claim it was in their 138000 volt (phase-to-phase) line. How do they come up with that number?
When you write 277+277=480, shouldn't one of the 277s be angled at 120 degrees from the other 277?
You have to add vectorially due to the 120 deg phase difference
Buujujujujujujjuuuuuuuui
Nice
Wow just repeated what he said...you must be a genius
Holy fuck this video is pure gold. Been looking for this for ages now.
Please explain how dyn11 works how it become out phase from delta? Thankd
If you mix all your sound onto the subwoofer channel, anyone with more than 2 speakers is going to just hear muffled bass when you talk.
Hi i like your video
The ease way is: E(line) =E(phase) x 1.73 or 270 v x 1.73= 467.1 v
Can you send me video on vectors n calculating the 480 in detail