3 Phase Ed and Dan's

[GerryS]

I'm a bit confused.  On Ed's page about 3-Phase (http://www.windstuffnow.com/main/3_phase_basics.htm) he shows that A, E, and C are the power outputs in this picture.  

Then I read Dan B's explanation (http://www.fieldlines.com/hotlist/add/2003/9/11/84741/6758/displaystory//) of wiring 3-phase and it shows a picture where A, B and C are grouped.    







.  

Ed says the power outputs are A, E, and C but DanB shows the equivalent of A, B and C being connected for star.  Based on Ed's description I would have connected A,E and C for star.  I'm confused.  

[windstuffnow]

  It's basically the same thing.   You have your start wires and end wires.   You can connect either all the starts or all the ends as long as you label them so you can distinguish the difference.   I used to label them as ABCDEF but I found that using a 1S 2S 3S 1E 2E 3E easier to distinguish between the phases.   Dan labeles them ABC XYZ but its all basically the same.   It would probably be less confusing if we used one method of marking the wires.   So, you should choose a method that makes sense to you when you wire them up.   I found using the phase numbers and the S or E ( start or end ) designation the easiest to keep straight in my head, the ABC method seems to work like a code in my brain and I have to decipher the code each time I work with it.

Hope that cleared up the confusion...

.  

[vawtman]

Ed, Your drawing is for a 12/36 right?

[Nando]

You have :

A B C

D E F

Where :

A - D coil one

B - E coil two

C - F coil three

For STAR connection tied D-E-F together and out A B C

Or tied A-B-C and out D E F

For DELTA :

Connect D to B ; E to C ; F to A ; output from the three points connection.

Is that clear ?.

Nando

[Darren73]

Nando,

The way it's shown in Ed's drawing A C and E are the starts, it's due to how he has drawn the coil / magnet layout.

Regards

Darren

[windstuffnow]

  One more note I should have mentioned, in the diagram above from my site - using 2 magnets for 3 coils you need to reverse the second phase.  This doesn't need to be done when using the 4/3 arrangement or the 1/3 only in the 2/3.  That could cause some confusion in itself with the different methods winding the alternator.  

  So as an example of a 12 pole alternator using a single layer of 9 coils or a 12 pole 36 coil there is no need to reverse the 2nd phase but the 12 pole 18 coil would require it.

.

[Flux]

This seems to be causing confusion at present, I have just answered this elsewhere.

When wound as Ed showed it, the coil displacement in the 12/36 is at 60 deg.

If the starts were taken from alternate coils and not the 3 adjacent ones the displacement would be 120 deg and the star point would be formed by joining the 3 starts( or finishes)

With the 60 deg displacement, phase 1 & 3 are at 120 deg and the middle phase can be corrected by reversing its start and finish. If you draw vector diagrams you can see why it works out, otherwise just accept it.

If the 3 phase winding is based on the alternative single phase with half the coils then this ambiguity can't arise, so the 12/18 version would not require the middle phase to be reversed.

It goes back to the single phase issue, with the same number of coils as magnets you must reverse alternate coils   S F F S S F. If you leave out the intermediate coils then yo connect the remainder S F S F.

When wound as a single layer winding of the 12/9 type there is no need to reverse any coil.

Flux

[Darren73]

Ed,

To clear up the confusion and show your coils with the standard letters would it be possible to swap the "B" and "E" on your diagram,

ie show   A E C     D B F

this should clear up the confusion for those who are new to 3 phase windings.

Kind regards

Darren

[GerryS]

Jackpot!    

That was indeed the issue Ed. So I do understand your drawing correctly...that for star in a 2 magnet 3 coil machine you would connect A,E and C in the middle?  Great!  

[ghurd]

I sketch out a design if I am having trouble following it.

The magnets get moved over in steps.

North is `up' so I make any wire over a north magnet carry current 'up'.

Wires over south magnets carry current down.  Really doesn't matter.

Works every time.

An example (sorry to butcher your shetch Ed).  The arrows show the direction of flow.

http://www.otherpower.com/images/scimages/2050/EdCoils.gif

G-

[GerryS]

I took Dan's picture and overlaid magnets on it.  For a 3 phase machine with 3 coils per four magnets, did I lay the magnets in the correct places?  

If I did lay the magnets in the correct places, then it is irrelevant which direction the middle coil is connected because it is equal in both positive and negative directions (it will add with one phase and cancel equally with the other phase...so hook it whichever way you want.)  Is that correct?  Ah-ha, I see.  So is that why the third phase is not included in the voltage total for 3-phase machines?  Because the third phase constructs and destructs equally.  Am I on the right track?

[GerryS]

ghurd, your sketch is nice.  Made it easy to visualize.  I made a sketch too.  Did I connect the wires properly for star?  

[ghurd]

You lost me on that.  

Nothing is being cancelled. Everything is being added together.

As shown, for a star connection,

The Blue coils have no voltage, and no effect.

The Red and Green are both at peak voltage, the voltage adds together, and current is flowing through through the Green coils, to the star connection point (where all 3 are connected) then into the Red coils.

[onefunkeedrummer]

Vaguely related question:  Ed's diagram seems to have the coils overlapping each other (roughly in thirds) while all the other diagrams I'm seeing have them adjacent to each other, side by side, bumper to bumper, etc.  Is one wrong and one right, or can you lay the coils down either way?