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.
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
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...





RE: Short single, dual and three-phase demo.
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.
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
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Short single, dual and three-phase 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
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Short single, dual and three-phase demo.
Thanks a lot.
It's intresting.
Best Regards.
Slava
RE: Short single, dual and three-phase demo.
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.
Sorry about that. Where is 98se used? Anything one can do about it?
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Short single, dual and three-phase demo.
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
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Short single, dual and three-phase demo.
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.
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.
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.
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.
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?
Am I mixing things?
RE: Short single, dual and three-phase demo.
Go to step 3 of the post and attach.
RE: Short single, dual and three-phase demo.
I must be missing a step?
Dave
RE: Short single, dual and three-phase demo.
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
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Short single, dual and three-phase demo.
Symetrical components is a powerful tool...
RE: Short single, dual and three-phase demo.
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.
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.
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
Regards
RE: Short single, dual and three-phase demo.
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.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Short single, dual and three-phase demo.
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
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Short single, dual and three-phase demo.
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
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Short single, dual and three-phase demo.
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.
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.
I have adjusted the excel sheet and I hope that it is correct now. Please check and leave feedback.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Short single, dual and three-phase demo.
Can you share your file or is it the same as what Mr. Englund posted?
Thanx
RE: Short single, dual and three-phase demo.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Short single, dual and three-phase demo.
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.
RE: Short single, dual and three-phase demo.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Short single, dual and three-phase demo.
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.
Here's my modified setup.lst file (see attachment)
RE: Short single, dual and three-phase demo.