How three phase math works (277 + 277 = 480?)
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- Опубліковано 17 вер 2017
- 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.
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
Excellent! Love the short, but explanatory videos. I first learnt the 3 squared method, so it’s good to hear this put another way.
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.
I am retired now, but I truly enjoyed working with three phase, wye and Delta configurations. Good presentation.
Great video. Studying for my professional architect licensing exams, and the detailed math explanation is actually very helpful as I am tested on multiple disciplines, including electrical, on my exams. Your breakdown of the math on this simple 3-phase diagram is very applicable to some of the structural engineering portions of my exams as well. Thank you!!
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.
Love the video. I've always understood why it was 480V but never saw anyone prove it with the vector math. Thanks.
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🙏🙏
Thanks for the refresher. It has been years since I first learned this. I am glad it still works! Haha
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!
I'm a level 3 electrical student and this is really helpful. Thanks a lot
Love your work my man !!
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
This is very helpful. Thank you!
Clear and concise explanation. Thank you.
Really good video.. Appreciate your channel.
Because of the particular angles involved, the square root of 3 can be derived easily from geometry without resorting to trig functions.
This helped me a lot thanks👍🏾
So well done! Thanks!
Awesome video, thank you!
I have three phase panel and it 120/208 with no high leg . Therefore it does not matter if I put a two pole breaker on a/b or bc or ca? And if I did have a high leg does it matter where the breaker get landed?
thank you for this great video :)
Nicely presented
Thanks for sharing
Thanks, this was an awesome simple explanation.
Glad you enjoyed it!
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?
thanks , very helpful and appreciate it
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.
You explained this very nicely 👌
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! .
awesome vid man. thx!!!
I would love to get the link to the other video mentioned 3:42, don’t have a way to PM here :-(
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.
Congratulations.. Well explained. Thanks..
You cannot directly add phase voltages because they do not happen at the same time.
Well said
What is the mac software you are using?
@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..
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?
Hey chad, your video is informative and it's great you given your break down on how to calculate line to line voltage however, i dont see how youre getting cosine value of 138.5. I watched your trg vids but how are you getting these values.
Type cos120(-277) that will equal 138.5
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.
Very interesting thank you for posting
Please explain how dyn11 works how it become out phase from delta? Thankd
Would it be the section of the arc when they intersect?
I love the internet! Thank you for a clear explanation!
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.
Awesome!!! Thank you so much
I have trouble with vectors. Please, the link?
Thanks very much SR
Root 3 works great,I was wondering about peak to peak,in UK they use 230v single phase is the peak to peak still 640 or is that only for 2 phase
Todd T 230 is the rms value. Vrms =vpeak / root 2. In a three phase system with the the voltage vectors 120deg apart but all he same magnitude, the phase volage = line to line voltage / root 3. I.e. 240v = 415/ root 3. Where 415 is the line to line voltage.
so the 3 armatures that are spinning to create 3 phase power are each 120 deg off from each other?
Very nice!
Thanks that explains it
Sqrt of 3 is derivable by using unit circle (assume phase voltage as 1)
5:42
Cannot locate your vector vid. pls help
Hi my name is Tim, I live in the uk, i purchased a balboa unit for my hot tub, to find it needs 2 110v hot feeds aswell as neutral and ground, we use 230v what do i neeed to power the unit up? any help would be appreciated.
Timberland Preston you need to find a step down transformer, and directly off of that add a disconnect and bond a neutral wire to your ground then run them both in parellel to your unit. If you want to do it properly youll need to drivd two 10ft ground rods in and run a ground directly from those to your disconnect. Or, purchase a unit designed for the voltages used in your country. Id say getting a new unit is probably a lot more cost and time effective.
Maybe hire someone that doesn't need to ask this question? Seriously, are you in over your head?
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.
Hi there im currently attending an Electrical Apprenticeship and was wondering if you could share that email on adding vectors ?
Can you send me vector calculation I'm little bit struggle in vector
The Wye system is also known as the star system
Interesting and educative
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?
can you please down load the fuse rating formula for 480 volts
How do you clean up the power
You are awesome man😎
GOD I remember figuring that stuff up. back in ET school
i get it sort of but, how can you use cosine and sine on this? thats only for right triangles..
thank you
Can I get a link for vectors how to to where to start
Well done
Can you send me video on vectors n calculating the 480 in detail
hi... have finished the 3 phase couse?
Hi great job
You wonderful Canadian thank you
I guess the 120 degree from one point to the other is a magnetic anomaly times the voltage ( 277) ? I'm so frgn lost so far
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
Im an electrical engineer (BSc.EE in 1996), and started in the electrical program at a trade school in 1980, graduated in 1984, and became a licensed journeyman electrician in 1985 at the age of 19... im now 51. point being that I have plenty of experience, education, and understanding at what can be described as an expert level. I can testify with all certainty that no matter how the voltages are generated in the world of physics, or how determined mathematically in an engineering environment by means of vector analysis, the bottom line is that all that stuff is what we call NICE TO KNOW in the real world. Its NICE to know, but isn't necessary in an everyday practical sense. The current flowing through the windings differs when dealing with a wye system like shown, than it does in the windings of a delta system (the other common 3phase system) by means of how these systems are actually physically constructed and wired. in a wye system, the line to line current differs from the winding current. it decreases from the line current by a factor of 1.73 because line current that flows when the line to line voltage(which is generated across two coils) is applied to the splits vectorily between the 2 windings generating the voltage. On a delta system, the line current is the same as the coil current because the voltage applied to a load is generated across only one winding and therefore only has one winding to flow thru... it's basically proof of Entropy- the 2nd law of thermodynamics, which States that the entropy of the universe is constant, and that energy cannot be created or destroyed.... it can only change States. Neglecting parasitic losses that affect efficiency of a system(ie, an ideal system) used to explain certain concepts, keep watts law in mind(a trade term for the math of ohms law used to figure out power). Watts equals volts times amps. the power into a system must equal the power out. if the voltage of a system increases, the current decreases by the same factor keeping the watts equal!
Yes sir, well said. Then there's "power factor" which is both NICE TO KNOW and knowledge of which can be so necessary in an everyday practical sense. Especially when one is functioning as Plant Engineer (electrical/mechanical, now retired) in a factory containing about 40 fairly large machines.....many powered by high horsepower DC motors controlled by modern DC Drives, and AC motors controlled by AC vector controllers.
Cant find your website 🤷♂️
how to measure brushless motor on oscillocope RC car 3 phase
Thank you
Thanks! Let me know if there is anything you'd like to see.
Still need help send link I want to learn more of the long way
Can one also explain this with 3 sinusoidal waves?
Those are the 3 sinusoidal waves that are 120° apart
Please send me the vectoral link
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.
Explain what is a DYN 11?
When you write 277+277=480, shouldn't one of the 277s be angled at 120 degrees from the other 277?
I understand that equipment using Phase A and Neutral will receive 60 Hz AC. But what I'm confused about is equipment connected to Phase A and Phase B. A becomes hot 60 times per second, and B also becomes hot 60 times per second, so wouldn't such equipment experience 120 Hz AC ? I'm probably just confused. Can anyone help me understand?
Every leg of the Y is 60 Hz and the phase to phase voltage is also 60 Hz. You can’t change the frequency by how you connect to it, only the voltage.
What is a PCB board
Can you put all three lines together?, and if so what is the math on that?
dgn107 I'm guessing you are asking how the math works for a 3 phase load. It is still Sq Root of 3 x voltage. So the number I use for 208 is 361 and for 480 is 831. So for an example primary of a 75kva transformer max amps would be 75000/831= 90.25 amps. Is this what you were asking?
Holy fuck this video is pure gold. Been looking for this for ages now.
How do I get the trig side? I want to give to my techs!
Mark Daniels sorry for the delayed response. I have a free course if you want it.
@@TheElectricAcademy wow... I never saw this. Yes, I want it.
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.
Thanks for the explanation but could you please send me the equation which gives the number of 208v instead of 240 for two phases in North America. How do I calculate it. Thanks
You get 208V phase to phase in a 3-phase system where each leg of the Y is 120V. You just multiply by the square root of 3, just as done here.
@@GH-oi2jf 👌
Thanks
Great 👍
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.
Explai how to get the root 3 please
“you probably think I’m smoking crack” “anybody see that fly flying around?” 👀
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.
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
5:12 , 138+416=554 and no explanation what 480 came from in video, why?
Question 3 phase 481 leg is
A 276
B 242
C 293