×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Short single, dual and three-phase demo.
8

Short single, dual and three-phase demo.

Short single, dual and three-phase demo.

(OP)
Hello! I have been giving short seminars on diverse topics in electric drives for many years. And one thing that seems to be very difficult for many people is why the standard mains voltage is sine formed. And also what a three phase system really is. Not to mention two-phase systems.

Add to that what harmonics are and their relation to the fundamental. So we made a short and simple demo program to show what is going on. I hope it is self-explaining. If not, I will add some instructions here.

Go to http://www.gke.org/test/ download, unzip and run the install wizard.  

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Short single, dual and three-phase demo.

Wow.  Pretty spacey vectors. Especially 3-phase with all harmonics even, and odd.

I wish you had more solid (wider) vectors that carried the color over to the graph so it was easier to tell which vector is causing what waveform.

Unfortunately I suspect this is not going to help much in the student realm.  Just my guess, but I believe more questions may be raised than answered.

Be interested to hear what you find in the classroom.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Short single, dual and three-phase demo.

6
(OP)
Right you are, Smoked!

It is intended to raise questions. And then I can use the system to answer those questions.

Like this one: How do even harmonics sum in a three-phase system. Easy to demonstrate - just run a three-phase system add even or non-triplene harmonics. Click "Show Sum" to see where the sum (the black dot) is and also see what happens to the neutral wave-shape.

Then do same thing with a two-phase 90 degrees system. Surprise! At least it was for me.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Short single, dual and three-phase demo.

(OP)
A short "Get started" for the demo:

Before you run, you should go to “Phase Configuration” under “Harmonics” and select “Single phase”. That is so that you do not get confused by several vectors.

You should also deselect all boxes under “Show harmonics” so that you do not get lots of harmonics to disturb you.

You may have to click the “Clear Graph” button under “Animation” and perhaps also “Run/Stop”. The box “Angle L1” shows the actual angle (L1 means phase 1 in the grid) from starting position. The angle is reset after 360 degrees. You can enter any angle in that box to get a new vector angle. You can also use the + and – keys to rotate the vector. Just experiment away!

When you feel like you want to know what a three-phase system looks like, you can go to “Phase Configuration” under “Harmonics” and select “Three phase”. There are also two two-phase options. The 90 degree option is what Tesla used for his first induction motors. The second system is sometimes still used in rural distribution – and also by some railway companies.

You can add harmonics to your liking. Just check the boxes and see what happens. The amplitudes of the harmonics are inversely proportional to their numbers. That is, third is 1/3rd and eight is 1/8th and so on.

The “triplenes” are interesting. They are always in-phase (pointing in same direction) with each other. That means that they do not cancel when added. They work together to produce a current if a load is connected between phases and neutral. Checking the box “Show sum” produces a black dot that shows the sum of all three voltages. As you can see, the sum of three phases without any harmonics is zero – the dot is staying in center of the system. If you add harmonics, you will see how the dot (the sum) starts moving around. One special case is when you have only the third harmonic activated. You will then see how the sum moves around a lot and that the projected wave-form to the right has a component that has thrice the frequency of the fundamental. This is what heats the neutral if you have lots of (third harmonic) distortion in your system. Ninth does the same thing. And so does sixth, but you should never have much of that. Even harmonics are not only unusual, they are also harmful.

There is audio as well! Not “to scale”. A 50 or 60 Hz hum isn’t heard very well through the PC speaker, so Lars took the frequencies up a bit so you can hear what happens when harmonics are added. Press “Play” under “Sound of L1” to listen. There will be a few seconds of silence while the program generates the wav file, which is then played through the speaker.  Adding more harmonics produces a “richer” tone.
 

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Short single, dual and three-phase demo.

Hi Gunnar.
Thanks a lot.
It's intresting.
Best Regards.
Slava

RE: Short single, dual and three-phase demo.

WARNING - DON'T try running this program on a WIN98se system.

It substitutes a nonrunning Oleaut32.dll in the windows\system folder.

This causes whole chunks of the OS to not load on startup.

Guess how I just found this out.

Regards, Ray.

RE: Short single, dual and three-phase demo.

(OP)
Thanks for the catch, Ray!

Sorry about that. Where is 98se used? Anything one can do about it?

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Short single, dual and three-phase demo.

(OP)
Hello again!

Thanks for the PLSes. I shouldn't have them, really, but our programmer Lars. I will transfer them to his pay account - with due reduction of number of SEKs, of course.

I am a bit concerned about that problem with WIN98se. We have run the program on four different computers with different OSes. From Win2000 via XP to Vista. I know that the Millennium was a trouble-maker, but have never seen the 98se and do not know anything it. Input most welcome! Anyone?

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Short single, dual and three-phase demo.

se was an upgrade from straight 98.  Probably most people who still cling to 98 are running se.

If you will notice rtronics stated which file was the issue.  Notice the '32'?  98 was not a 32 bit OS if I remember correctly.  So as soon as your program landed a 32 DLL in his system he was bound to have an issue,<screwed>.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Short single, dual and three-phase demo.

Hello Skogsgurra

I had no trouble with the program and thanks BTW for it I am finding it interesting, also watching for input and questions from others.

For the people having trouble with the older operating systems I would think they could run it in compatibility mode, this is a feature specifically for these conditions.
 

RE: Short single, dual and three-phase demo.

Except compatibility modes are for backwards  compatibility.  If Skoggs program uses a 32bit program and 98se doesn't understand 32bit programs a compatibly mode probably won't help.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Short single, dual and three-phase demo.


Ah yes, correct you are. Like they say "My bad!"
 

RE: Short single, dual and three-phase demo.

Skogsgurra,

I've got a similar demo that is all in Excel.  How do I upload it so I can share it with you and others?

RE: Short single, dual and three-phase demo.

Nice... but I have one hell of a question:

In a balanced 3-phase system, the fondamental, 7ht, 13th...
are direct sequence and are turning counter-clockwise.

Should'nt the 5th, 11th, ...  be turning clockwise? ponder

Am I mixing things?   


 

RE: Short single, dual and three-phase demo.

Hi Magoo,
Go to step 3 of the post and attach.

RE: Short single, dual and three-phase demo.

So for some reason, I can't install this on my XP system.  When I run the installer, I get an error message saying the system files are too old and that it will update the system files, but then I need to restart my computer and re-run the installer.  After doing this twice, I get the same error.  

I must be missing a step?  

Dave

RE: Short single, dual and three-phase demo.

(OP)
unclebob,

This is exactly one of those questions that this demo rises.

The harmonics as such all turn in the same direction and that means that the rotation speed is proportional to the frequency. So, the demo is correct. The positive direction has been chosen for the whole system and that means that all vectors rotate in the same direction. The fact that the projected wave-form is what one would expect from the given mix of harmonics is also, I think, an indication that the demo does the right thing.

The statement that some components are zero-sequence, some are positive and some are negative sequence pertains to a distorted system decomposed into symmetric components. I am not so sure that one can translate that directly to this demo.

But, I would love to have someone's view on this. I have asked myself quite a few questions in the same direction when I have tried different set-ups. Especially the role of triplenes in a two-phase system. In such a system, they do not add. Contrary to my belief.

David,
I had the same problem until Lars told me to unzip all files and then run the install wizard. Must be someone out there that can put that into a step-by-step instruction.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Short single, dual and three-phase demo.

Was reading about harmonics in ubalanced systems. In unbalanced systems, symetrical components are applied on the fondamental to describe direct, inverse and zero-sequence. When adding harmonics, symetrical components are applied to each and every harmonic, thus decomposing them in direct, inverse and zero-sequence components.

Symetrical components is a powerful tool...glasses

RE: Short single, dual and three-phase demo.

Sorry, my previous post was incomplete.

If and only if the system is balanced, then it is true that:

Harmonics 1, 4, 7,... are direct sequence;
Harmonics 2, 5, 8,... are inverse sequence and
harmonics 3, 6, 9,... are zero sequence.

Isn't that amazing!!!

RE: Short single, dual and three-phase demo.

Gunnar,

Yes, that what I did and I just did again - still getting the same error message after rebooting.  Must be a conflict with some other program.  

Dave

RE: Short single, dual and three-phase demo.

Unclebob, Gunnar:

I agree with Uclebob when he says that

Harmonics 1, 4, 7,... are direct sequence;
Harmonics 2, 5, 8,... are inverse sequence and
harmonics 3, 6, 9,... are zero sequence.

And, as Gunnar says, all of this vectors turn the same direction.

When we say that for example, harmonic 5 are inverse sequence, we mean that the 5th harmonic of phase B reaches its maximum instantaneous value before the 5th harmonic of phase A.

Just draw the sine waves and see smile

Regards



 

RE: Short single, dual and three-phase demo.

(OP)
Yes, Yuma. That is the explanation to this contradictions as it seemed to be. The phase sequance has nothing to do with if the individual harmonics rotate CW or CCW. It is about in what order the three phases cross zero in positive direction.

You can easily see that in the demo by setting fifth harmonic only and rotate the system manually with + and - keys (focus on Angle L1 box first). Then observe how L2 green component reaches positive peak before L1 does so.

Kill fifth and do the same thing with fourth. See how L1 yellow reaches positive peak before L2 yellow does. Meaning that L1 fourth comes before L2 fourth - positive sequence.

Kill forth and avtivate third. See how all three orange components always point in the same direction - i.e. they are zero sequence.

You need to think about these things. I haven't realised this until now. sad  But I am certainly glad I finally did  smile

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Short single, dual and three-phase demo.

(OP)
Yuma,

It was a hell of a lot of work to draw all those sines! So, I did a simple Excel sheet to show what you just said.

And thanks to Dan Ward at Dominion Virginia Power, who sent me an Excel sheet doing "my thing". I hope that you can use the "Step 3 Procedure" to make your sheet available. I am going to try that. If it doesn't work, I will add it to our site later on.
 

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Short single, dual and three-phase demo.

(OP)
Oops!

I think that I reversed the whole thing.

Too late over here. Someone correct my mistake? Or I do it tomorrow. It is close to mid-night now.

Dan: The "step three" thing is what you do when you are posting here. See red text below Message box.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Short single, dual and three-phase demo.

Thanks, Skogsgurra

I looked all over the site for instructions, but never looked at the bottom of where you send your message.

I hope you enjoy the Excel piece.  It doesn't do harmonics, but does a nice job with phasors.

Dan

RE: Short single, dual and three-phase demo.

I have asked myself quite a few questions in the same direction when I have tried different set-ups. Especially the role of triplenes in a two-phase system. In such a system, they do not add. Contrary to my belief.

Depends on which system you are talking about. In a 90 degrees shift, two phase system, the 3rd harmonics do add and the program shows this correctly.

In a 180 degrees, two phase system, the 3rd harmonics will cancel each other out and again the program shows this correctly. This is the equivalent of using a transformer with a centre tap which is used as the common and the top and bottom legs 180 degrees out of phase. This is quite commonly used in sites where clean power is required. Using this dual active approach gets rid of any common-mode noise between the two supplies and in this case the 3rd harmonic can be considered common mode.

Nice program, Gunnar. I wish I had it a few years ago when I was teaching in-house courses to engineers and techs who were new to the power game.

RE: Short single, dual and three-phase demo.

Quote:

Skogsgurra,

I've got a similar demo that is all in Excel.  How do I upload it so I can share it with you and others? ...

Can you share your file or is it the same as what Mr. Englund posted?
Thanx

RE: Short single, dual and three-phase demo.

(OP)
No, it is another one. I think that Dan/magoo2 shall do it. He "owns" it and he also knows how to do it now..

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Short single, dual and three-phase demo.

This is the program (Excel worksheet) I sent Gunnar.  I found a phasor worksheet on the web by a Professor Bruton of SFASU.  He had a demo showing 2 phasors and it looked pretty neat.  I think he did it for a math class.

After I looked at what he had done, I added the three phase representation and it works quite well.  You need to turn off auto-calculation and make it manual.  When you strike the F9 key, you'll see the 3 phasors rotate and you'll also see the voltage versus time plot.

I was just getting ready to do a short course on symmetrical components when I found this.  It doesn't do harmonics, just the normal three phase phasors.

It's pretty slick - if I do say so myself.  Enjoy!

RE: Short single, dual and three-phase demo.

Kudos Gunnar! This is a cool demo, great for trying to educate the Salesman types.  However, the displays seems just a couple lines too large for my screen and can't be reduced in size.

RE: Short single, dual and three-phase demo.

(OP)
It will work better on your next 'puter. Shall have a look at that "Auto-adjust to screen resolution" feature. But lots to do right now - so no promises.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Short single, dual and three-phase demo.

I got the same error that the gentleman did above trying to install the software on Windows XP.. re files too old...

I was installing it on Windows 2000.

btw. I edited the setup.lst file to remove the instructions installing and registering the *.dll files and reran setup.
 
The program installed and runs successfully..

You need to look into the dlls you your app is trying to install vs operating system level...

Nice demo program!

http://home.4x4wire.com/deddleman/

RE: Short single, dual and three-phase demo.

It would be great if you could show the resultant vector and then be able to turn on or off the harmonic vector displays (keep them running in background) but just show the resultant thsu to demonstrate the effect of the harmonics.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources