Three phase electric power and phasor diagrams explained

[@EugeneKhutoryansky]

To see subtitles in other languages: Click on the gear symbol under the video, then click on "subtitles." Then select the language (You may need to scroll up and down to see all the languages available). --To change subtitle appearance: Scroll to the top of the language selection window and click "options." In the options window you can, for example, choose a different font color and background color, and set the "background opacity" to 100% to help make the subtitles more readable. --To turn the subtitles "on" or "off" altogether: Click the "CC" button under the video. --If you believe that the translation in the subtitles can be improved, please send me an email.

[@parmanandsharma6682]

Hindi

[@EngineeringMindset]

Great visualisation Eugene

[@EugeneKhutoryansky]

Thanks.

[@AyanThakuria]

both of you are awesome ..

[@EugeneKhutoryansky]

If you like this video, you can help more people find it in their KZbin search engine by clicking the like button, and writing a comment. Thanks.

[@jamesdean1074]

Thank you. Did as you suggested.

[@EugeneKhutoryansky]

All the music in this video is from the free KZbin audio library, and the names of the songs are the following. Wigs Fur_Elise_by_Beethoven Double_Helix

[@jagdishpatankar3603]

Physics Videos by Eugene Khutoryansky

[@borisdorofeev5602]

I've been a sub of yours for a while. You have one of the most visually intuitive minds. It's so beautiful to see mathematical, scientific, and theoretical concepts depicted in 3d. It may not always be a perfect representation of reality but neither is art. In the same way, as art, I really enjoy it for what it is. Thanks for the hours of great content Eugene.

[@chayankhan2615]

Pls make a video about transistor acts as an amplifier... And also as a switch

[@peter.g6]

This was a great video. I'd just add a few things if anybody is wondering about this and wants to make a little more sense out of it: - "Line To Neutral" is called "star" connection or "wye" connection (or Y-connection), and "Line to Line" is called "delta connection" (and sometimes "triangle" connection). - Phasor is actually a complex number that represents a sine wave, assuming a concrete frequency is given. If frequency is given, only amplitude and phase shift are needed to fully describe the sine wave. This is expressed by a complex number, and in polar coordinates it's length describes the amplitude and the angle describes the phase shift. It's a nice mathematical trick to simplify computations. Where's the advantage? For example, adding two sine functions results in another sine function, but the math to find out this new sine wave is annoying. To easily determine what it looks like, you can just add their respective phasors as complex numbers (i.e. as vectors) and you'll get a phasor of this new sine wave. Simple, right? Of course, you have to do the annoying proof that this is true, but from then on you can enjoy simple computations. Using this, you can easily compute that the voltage between two lines is √3 times the "Line To Neutral" voltage - simply by subtracting one "Line To Neutral" phasor from another (subtract, because voltage is a difference between two potentials). In other words, you are subracting two vector of the same length and a 120 degrees between them. This leads to a right triangle with a 60 degree angle, and cosine of 60 is (√3)/2 -> that's how this √3 pops up. - Using Phasor arithmetics you can also verify that the current in the wires between two Lines will be √3 times SMALLER than the current in the single Line (the one that goes all the way from the source to your Delta connection starting point). (Amazingly, you can see that in the video, that the red dots are moving slower when "in the triangle".) This means, that for both connections, if the same current is drawn from each of the lines, the same power (voltage times current) is consumed. The difference is, that in the Delta connection your device will use higher voltage and smaller current internally. This makes perfect sense, right? You simply have some power coming through those individual lines and regardless of you you decide to "harvest" it, you'll get the same amount of it. So (I assume) this delta connection is used in devices which have components with higher resistance inside, but still want to use some serious power. ------- I hope I've described it properly. I was confused about some of these things recently so I did my research and I hope this helps somebody else.

[@Antoine7881]

Have you ever heard of a straight power Delta bank aka ungrounded Delta bank transformers on a utility pole? 240 phase to phase. Zero to neutral.

[@macronencer]

Thank you! This is a very helpful comment.

[@bluedart7663]

thank you.. crystal clear

[@kyutimong1362]

Woah thank you for the explanation sir

[@ishworshrestha3559]

Ok

[@guilhermegondin151]

I truly can't express in words how much I love this channel

[@EugeneKhutoryansky]

I am glad that you like my videos that much. Thanks.

[@guilhermegondin151]

You've managed to fuse low poly anymation (wich I love) with the most didact explanation I've saw in my life, also the narrator is great, her voice makes the content seens interesting even in videos that are not from my area and dislike readinng books on the topic. Nearly perfect team you have, and isn't perfect just because nothing is, I couldn't find any flaws.

[@joshuacaldwell5887]

I struggle to understand a few things in electrotechnology but heaps of different visuals and analogies and alternative ways of describing things and it slowly starts sinking in. Down side is it takes time but up side is you develope a deep deep understanding that is so satisfying.. so thanks for the vid

[@EugeneKhutoryansky]

I am glad my video was helpful. Thanks.

[@mranonymous8085]

This woman is my hero...I have cleared my most basic concepts because of her videos... I would really like to meet her

[@pinky-qn1wp]

Это чудовищный проект) Из серии: "Как запутать нуба, чтобы отбить навсегда желание заниматься электроникой")

[@МаксимД-э6п]

лайки ставят за красивые картинки:?

[@pinky-qn1wp]

@@МаксимД-э6п Ставят за "залипательность" картинки, которая автоматически транслируется в мозг как "продвинутость". И отчасти лайки обозначают актуальность темы радиоэлектроники. Электроника познаётся только на базе личного опыта(после уяснения теории в виде связных фраз и терминов).

[@МаксимД-э6п]

@@pinky-qn1wp мне показалось что ролик полная шляпа

[@pinky-qn1wp]

@@МаксимД-э6п Смотря в чём. Их уже целый сериал наделан.

[@jacobhoward7579]

After 3 long months one of the Physics Wizards of You Tube has graced us with another video! What a joyous occasion it is!

[@miskryikealo6586]

I had a hard times understanding the science behind 3 phases and phaser diagram in Eritrea Africa ....Alas I understand vividly that our education needs a serious revision and transformation.Thank you ,physics is phenomenal it has revolutionized Men's life .

[@EugeneKhutoryansky]

You can help translate this video by adding subtitles in other languages. To add a translation, click on the following link: kzbin.info_video?ref=share&v=EzDs6jPrpFw There is a similar message now pinned at the top of the comment section of each of my videos. When you are done providing the translation, please remember to hit the submit buttons for both the video subtitles and for the video title, as they are submitted separately. Details about adding translations is available at support.google.com/youtube/answer/6054623?hl=en Thanks.

[@robertcalkjr.8325]

It would be nice if the music was cut out...

[@kwgm8578]

Thanks Eugene. I enjoy your videos and usually learn something, even when I'm already familiar with the subject. Your films should be a part of every undergraduate physics and engineering program.

[@EugeneKhutoryansky]

@@kwgm8578 Thanks.

[@sec_g_69shreyashsrivastava72]

Plz uploading more vedio you are great physician

[@CASH-TO-THE-MERE101]

Physics Videos by Eugene Khutoryansky 🔥🔥🔥

[@pulakdas8998]

My favourite topic and my favourite physics channel joins. This is what I need to be happy........!!!! Love this channel so much.......!!!

[@pulakdas8998]

.....

[@EugeneKhutoryansky]

Thanks. I am glad you like my videos.

[@paulcleary8638]

Eugene. your videos are so unique with the visual volt drops totally different approach and so much easier to remember . I have learnt so much from them over the last year or so . Never seen a sine wave created in that way before either. really amazing . thanks so much for your time and effort.

[@EugeneKhutoryansky]

Thanks for the compliments. I am glad my videos are helpful.

[@hinkles73]

I'm glad your videos don't have the comments turned off because then I can comment on how much I like your videos!

[@EugeneKhutoryansky]

I am glad you like my videos. Thanks.

[@monteiro5306]

A long, long time..Awesome video,another Eugene Khutoryansky masterpiece. Greetings from Brazil.

[@EugeneKhutoryansky]

Glad you liked my video. Thanks.

[@krishnendughosh1712]

No body can explain ,like this. I think this channel is under rated.

[@EugeneKhutoryansky]

Thanks.

[@davidcraig9779]

The 3 offset sinewaves still look like DNA to me. Nice, simple tutorial. Thank you so much.

[@seshrut]

i spent way too long on such a short answer... i like this channel

[@jamesdean1074]

Thank you for changing lives and inspiring people.

[@EugeneKhutoryansky]

Thanks.

[@stevewatts9128]

I just can't quite express how utterly brilliant this animation is

[@EugeneKhutoryansky]

Thanks for the compliment about my animation.

[@tartaric2040]

Mr Eugene, you are really doing very interesting work here on this KZbin channel. Many learners are getting intuitive understanding by your videos. I really hope you can increase frequency of uploading videos and add more content on this channel. Such visual learning experience through your videos is rarely available through other sources.

[@EugeneKhutoryansky]

Thanks for the compliment about my videos. More videos are on their way.

[@NavjotSingh-dy4iu]

Eugene is back with another great video!

[@a1919akelbo]

3 phase is probably the greatest bombshell to drop on people who just got how AC works.

[@quahntasy]

After such a long time. Amazing visuals as always. Thanks for existing!

[@lucasmiller9081]

this is the first time i’ve seen phasor diagrams animated and it ALL MAKES SENSE NOW

[@davidgarza6988]

Holy sht. What a great video. Shortcuts many hours of learning through studying. Many thanks!

[@EugeneKhutoryansky]

Glad my video was helpful. Thanks.

[@halmirofigliolo1637]

Hi Eugene, I have a question! What would happen if the loads were different?

[@samarthtandale9121]

Wow! What a great explaination about star connection in an ac supply! Keep it up Eugene 👍🤩🙌

[@EugeneKhutoryansky]

Thanks. I am glad you liked my explanation.

[@MrThinhle]

Thank you for all these great videos

[@EugeneKhutoryansky]

Thanks. I am glad you like my videos.

[@darkminds5391]

Thank you so much. Honestly I was banging my head to visualize this. Continue this✌️😍

[@EugeneKhutoryansky]

Glad my video was helpful. More videos are on their way. Thanks.

[@4pharaoh]

Very nice introduction. Your graphics are off the chart.

[@EugeneKhutoryansky]

Thanks for the compliment.

[@phenomadit1821]

The first subscribed channel by me of KZbin

[@EugeneKhutoryansky]

I am glad to have you as a subscriber. Thanks, and I am glad you like my videos.

[@phenomadit1821]

@@EugeneKhutoryansky THANKS ☺☺

[@rimsonworks]

Your way of teaching by current animation is The Best Please also introduce videos of electrical panels of machined Contactors relays timers etc And PLC programming Thanks

[@migueluribe4249]

If I need 240 or 220 volts from a three-phase. Can I use only two of the wires to run a non-threefasic motor?

[@James-cb7nb]

Damn that animation going from circular to sinusoidal motion was sick

[@ayaan5540]

IKR! I first saw it on the video about the Fourier Series on this channel and it had never occurred to me that circular and sine waves could have that relationship. It just clicked so beautifully and changed my intuitive understanding of sine wave altogether.

[@EmilFihlman]

This channel is one of the best on KZbin!

[@EugeneKhutoryansky]

Thanks for the compliment.

[@shamsurrehman3566]

I am from Pakistan I like your video's and I also show to my students in class with the help of multimedia please make a chinal list and if possible please make vedio regularly

[@skyknight5436]

Pakistan school students ...come on terrorists....show your students how not to bomb other countries...

[@hariohm1415]

Chinal or channel ? Lol😜😜😜😜😜😜😜

[@jannegrey]

One of the best channel that explains Physics in simple, but effective way, and using really good animations, that give necessary information. I have to check out other videos about current. I already watched a lot about quantum Physics etc. The only thing I cannot exactly understand are tensors (why are they used? I know that they're supposed to make it easier when you change the axis etc. - I simplify - But I cannot grasp exactly why). But that's not your fault. That's because I don't work with them, so I cannot apply them - and I've learned that application is the best (for me) way to understand something.

[@EugeneKhutoryansky]

Thanks for the compliment about my videos. In reply to your question, one of the areas where tensors are used are in Einstein's Field Equations of General Relativity, describing how mass/energy causes a curvature in space-time. As you are probably already aware, I have a video on Tensors and another video on Einstein's Field Equations. Thanks.

[@ugurbayrak9869]

Hey Eugene, that's very unique and incredible representation of phasors. Thank you for these study. As you said me before, I am waiting for your another videos on electrical generation&magnetic field subject, generators etc ;)

[@EugeneKhutoryansky]

Thanks for the compliment. More videos are on their way.

[@jacek7178]

The music distracts terribly. Can you switch it off? It would be very nice and pleasant.

[@a.o.3523]

Always appreciate your videos!

[@EugeneKhutoryansky]

Thanks.

[@xyzct]

A picture is worth a thousand words.

[@ILDemoneRossonero]

I study electrical engeneering , this is my work !!!!!!!😁👍

[@phenomadit1821]

Then you know a lot of this video already isn't interesting.

[@nasajetpropulsionlaborator8727]

Nobody asked wire fairy

[@ivern1]

Спасибо Вам за такие материалы! Просто чудо

[@Artaxerxes.]

3:45 that was just beautiful eugene. How did you come up with that ? I'd never imagine visualizing it like that

[@EugeneKhutoryansky]

Thanks for the compliment.

[@unknown-ql1fk]

I wish i had access to this channel back when studying electrical engineering. now in a professional biologist, its way easier to see visual representations then math equations

[@pokefan2711]

If a bulb have a different resistance, it would need the common neutral?

[@TheLonelyTraveler142]

Very interesting how complex numbers prove useful for alternating current. Thanks!

[@shirshak6738]

i knew new video is going to come after i saw u online at facebook :) Long live our engineering hero eugene :)

[@tseckwr3783]

Another excellent video by Professor Eugene ... thanks, I really do enjoy them.

[@prudhvirajdasari2723]

After a long time

[@Manharsh]

Please tell me The electricity we use at home is 2phase or 3phase????????????

[@EugeneKhutoryansky]

Each home typically gets only two of the three phases. Think of your house as one of the light bulbs in the video.

[@4pharaoh]

In the USA and Canada, the main supply is fed to a three phase transformer. That transformer will send 240volts split phase. Single phase but split in to two feeds of 120v each that are 180 degrees out of phase with each other. The other two phase outputs feed other houses or groups of houses. Just like the three phase discussed in the video, the split phase (240/120) saves wire.

[@JustinL614]

@@4pharaoh Yes. Interestingly enough I've witnessed that some of the homes in flood zones have 3 phase in the USA for sump pumps but most of the time it's 2 phase.

[@buddingscientist170]

Nice explanation👌👌👍

[@EugeneKhutoryansky]

Thanks. Glad you liked it.

[@P.James.7070]

This talent is unbelievable to me.

[@EugeneKhutoryansky]

Thanks for the compliment.

[@bryan5327]

Well done! I'm learning about AC circuits and the animations definitely help. Btw, what software do you use for the animations?

[@EugeneKhutoryansky]

Thanks. Glad my animations were helpful. I make my 3D animations with "Poser."

[@bryan5327]

@@EugeneKhutoryansky nice!

[@willybanus7900]

Best channel ever!! Thank you!!

[@EugeneKhutoryansky]

Thanks for the compliment.

[@СергейБочаров-г5з]

Я чет немного не понял. По этому видео получается что ток в зависимости от вектора меняет свое направление? Думаю афторов линчевать нужно.

[@simplkolchin]

Именно так, ток в лампочке 50 раз в секунду меняет свое направление, именно поэтому и называется переменным. На самом деле лампа накаливания мерцает, просто из за инертности мы этого не замечаем.

[@СергейБочаров-г5з]

@@simplkolchin ru.m.wikipedia.org/wiki/Переменный_ток Прочитайте внимательно раздел синусоидальный ток. И раздел применение переменного тока. Ток всегда идет от фазы к нулю.

[@simplkolchin]

@@СергейБочаров-г5з Замечательно что вы потрудились найти хороший материал. Вас ничего не смущало при написании слова синусоидальный? это функция описывающая периодические процессы, такие как маятник в приведённом вами примере. Направление тока это условность , принятая для рассмотрения физического процесса в конкретный момент времени. Вероятно вы путаете направление тока и направление мощности. Направление мощности зависит от фазового сдвига между током и напряжением и направлено от источника к приемнику электроэнергии.

[@СергейБочаров-г5з]

@@simplkolchin допустим вы невнимательно, но все же прочитали. Изучаем матчасть дальше. ru.m.wikipedia.org/wiki/Электрическая_сеть

[@СергейБочаров-г5з]

@@simplkolchin нет ощущения что провод для передачи тока один. Если б в нем он бегал в разные стороны, передачи энергии не было б. Как же так?

[@VoidHalo]

It would be really great to see you do a video on passive filters.

[@EugeneKhutoryansky]

I have that in my video on AC current impedance at kzbin.info/www/bejne/sICag42QjJWqibM

[@oldmangranny5oldmangranny56]

Eugene this is off subject I know. How do we know that a black hole singularity actually has volume = 0? Why couldn't it be approaching 0 as an asymptote? Cheers.

[@carultch]

Definition. That's what a singularity is. The real question is, how do we know that black holes actually have their mass concentrated in a singularity in the first place? Because it really could be any volume smaller than the event horizon, if we didn't have further information.

[@VoidHalo]

I wonder if the wye configuration is where they got the idea for how the flux capacitor looks in Back to the Future. If you watch an animation of a DC current flowing into a central ground in the middle of a wye configuration, it looks exactly like the flux capacitor. And for those interested, such an animation can easily be visualized with an online circuit diagram app. Look for CircuitMod and give it a try. I have no affilliation with CircuitMod, but it's been one of the most helpful tools I've used for understanding this stuff. Short of building actual circuits yourself, it's probably the next best thing.

[@GauravKumar-dr2yk]

Some of the best video on youtube...

[@EugeneKhutoryansky]

Thanks.

[@322stevo]

Very well made videos. I do enjoy the spacetime ones better.

[@Maddy-mv6sd]

A very good content available across the youtube....

[@MACROPARTICLE]

I'm currently working on an engineering project, and noticed how three-phase power can be used to drive a brushless motor. Unfortunately this requires some form of controller. If possible, could you produce a tutorial on the circuitry of a brushless motor controller? Probably not, since it features a complex system of sensors and transistors, something very difficult to replicate by hand.

[@ironmaz1]

Nono physics or elec. engineering student here... yet I find these videos interesting! I don't understand at 2:35 why is it the case that for I=0 you can remove the wires... why can't you for non-zero total current?

[@jkinkamo]

Neutral wires. Provided the each phase has exactly the same load.

[@ConstructionMarketing]

Would you consider licensing some of this footage for use on large electrical contractors website? If so let me know.

[@EugeneKhutoryansky]

I will not be licensing the footage, but anyone can create an "embedded link" on their website that links to my KZbin video. This will probably have the same effect that you are trying to create. Thanks.

[@usama57926]

great video great animation and great explanation

[@EugeneKhutoryansky]

Thanks for the compliment. I am glad you liked my animation and my explanation.

[@johnstown2451]

At 5 min, we’re thought the sqrt of 3 but I don’t know why. Is it because there’s 3 lines? Where does 1.73 come from and why?

[@MeltingRubberZ28]

I'm asking myself the same question. I also believe it's because there are three phases but can't say for sure. I do know the math works correctly for it.

[@johndaad3316]

Thanks sir....alot of love from Pakistan... I subscribed your channel...I hope I'll get much more knowledge...once again thanks

[@EugeneKhutoryansky]

I am glad to have you as a subscriber. Thanks.

[@Limit-xm7bf]

Nice Keep up the good work!

[@EugeneKhutoryansky]

Thanks. More videos are on their way.

[@bananabeansyoho7781]

You made me survive my A levels man

[@shyamsn2124]

Wow nice video ma'am i like this video

[@dustinsmith8341]

The creator is male, the voicework is female.

[@Felixieno_00]

When the guitar kicks in you know your mind is about to blow

[@panagiotissaliaris8357]

Very nice work!! What's the software that you used to make this video?

[@EugeneKhutoryansky]

Thanks. I make my 3D animations with "Poser."

[@borisdorofeev5602]

Yes! Eugene is back.

[@pullingrabbitsouttaahat]

Very Nice and Graphic Explanation. Thank You !

[@EugeneKhutoryansky]

Thanks for the compliment.

[@thecoolman9909]

Please do animation\explanation video about Atomic Reactors. Thank you for your vids

[@sammyapsel1443]

Whats the name of the piano piece playing in the background?

[@EugeneKhutoryansky]

All the music in this video is from the free KZbin audio library, and the names of the songs are the following. Wigs Fur_Elise_by_Beethoven Double_Helix

[@NeedsEvidence]

1:05 "Let's call these phase A, _[suspenseful pause]_ phase B _[an even longer dramatic pause]_ and phase C." Phew, I didn't see that coming!

[@paulaalessandraramirez]

Isso é para ajudar ou para complicar?

[@eros_1234]

Your videos are awesome and excellent

[@EugeneKhutoryansky]

Thanks for the compliment. Glad you like my videos.

[@RamRam-zv5od]

amazing, please tell me which software using. Really great

[@EugeneKhutoryansky]

I make my 3D animations with "Poser." Thanks.

[@luigigagliardi7477]

Great animation! What software did you used?

[@EugeneKhutoryansky]

Thanks. I make my 3D animations with "Poser."

[@luigigagliardi7477]

@@EugeneKhutoryansky Thank you!

[@kauship5353]

can you please make a video how photo reflect from mirror and light slows down in glass or water

[@EugeneKhutoryansky]

I cover reflection in my video at kzbin.info/www/bejne/oJrJoqaugbeFjc0 and I cover refraction in my video at kzbin.info/www/bejne/fXaQh5h7hqukjpY

[@NEMountainG]

Why does line to line offer a larger voltage compared to line to neutral? Also, thank you for this fantastic video yet again!

[@EugeneKhutoryansky]

You can visualize this by looking at the differences in elevations in the video. The differences in elevations represent the voltage differences. Thanks.

[@ウラルグール]

Тихий ужас! Бедные студенты! Нам на обычной доске мелом за пять минут всё объяснили так, что хватило на всю жизнь и мы других ещё учили. От такой анимации хочется всё бросить и пойти напиться. 😀

[@coloradowilderness3139]

Need to indicate Conventional Current in this animation. Best wishes .

[@R-zd9tc]

Thanku sir.🙏🙏🙏🙏🙏🙏 This video help me a lot.

[@R-zd9tc]

Please make a detail video on this topic.

[@WildEngineering]

great video and great music choice! good job bro!

[@EugeneKhutoryansky]

Thanks.

[@WildEngineering]

@@EugeneKhutoryansky i just uploaded a video last night on DC to DC isolated converters. if you would check it out it would mean a lot to me!

[@vigneshsankaran2638]

Great video 😍. Could you please do a video on Rotating magnetic field ? Thanks in advance 🙂

[@EugeneKhutoryansky]

Thanks. I covered rotating magnetic fields in my video on Maxwell's Laws of Electromagnetism at kzbin.info/www/bejne/b4XQY5Zsg697ars

[@Manharsh]

Waiting for your video from Long time..

[@thanostzia]

The legend is back!

[@luculliana]

Physics Videos by Eugene Khutoryansky , (water)ice is supposed to exist in about 17 different forms. Can you make a video showing the molecular ice forms in 3d and how all these different transitions occur? Thanks

[@justraja100]

Wow, that was pretty clever!!

[@tanerriffat7963]

In electronics could we please have some videos on phasors, polars and root mean square (rms) and the trigonometry (sin, cos, tan) needed to put it altogether. I think this would be a series of videos starting with radians to degrees to sin, cos and tan to phasors, polars and rms. Assume I know very little so start with the geometry and end with rms and how to calculate and apply reactance and Independence formulas for circuit analysis, wave-forms and phasors using ICE and ELI in AC circuits. A big ask but would help all electrical engineering students...

[@EugeneKhutoryansky]

I already have videos on many of those topics. For example, my video on trigonometry is at kzbin.info/www/bejne/paevk3asppx5hKM As for reactance and impedance, I cover this (without the mathematics) at kzbin.info/www/bejne/sICag42QjJWqibM

[@tanerriffat7963]

@@EugeneKhutoryansky Thanks!

[@narensuri3471]

what tool do you use for these visualizations?

[@EugeneKhutoryansky]

I make my 3D animations with "Poser."

[@zhiyuan2034]

Interesting，With what software?

[@EugeneKhutoryansky]

I make my 3D animations with "Poser."

[@macronencer]

Please do one explaining Ring Modulators! I'm really struggling to understand how they work. Thank you!

[@sciencewithfun480]

Awsome first time i ever understand phasor Actually

[@rodrigoappendino]

I don't understand why you can remove the wires in the middle just because the sum of the voltages is zero.

[@jkinkamo]

At 2:30 the current at the neutral wire is zero if all the three phases have the same load, e.g. in three phase motors or heating resistors. Both (the generator and at the load) starpoint voltages are equal. So you can remove the neutral. In households the situation is not necessarily so. In my house there is a combined neutral and protective earth running from the distribution transformer (star connected secondary midpoint). Neutral and protective earth are separated at my metering panel. So my house (virtual) starpoint is connected to the distribution transformer starpoint. Also I have lots of single phase gadgets running on 240 volts (between phase and neutral) instead of 400 volts (between two phases), so neutral is normally needed.