Winding Generator
Winding Generator
(OP)
Hello All
We was requested in order to make a new winding for one generator the name plate is : 3.5 MVA 5.5 KV 367.4 Amps Cos Phi 0.9 12 Poles 50 Hz 500 RPM. The slot numbers are 144 and the winding have 72 coils. So only one coil side in each slot single layer windind. The attached drawing shows the following : One coil will be inserted in the top of the slot and the bottom`s space is filled. Then other coil is inserted at bottom of other slot and top is filled.Take a look of the attachment.
Any one with experience with this windings, all explanations and inputs will be wellcommen.
Thanks and regards
Pirulo
We was requested in order to make a new winding for one generator the name plate is : 3.5 MVA 5.5 KV 367.4 Amps Cos Phi 0.9 12 Poles 50 Hz 500 RPM. The slot numbers are 144 and the winding have 72 coils. So only one coil side in each slot single layer windind. The attached drawing shows the following : One coil will be inserted in the top of the slot and the bottom`s space is filled. Then other coil is inserted at bottom of other slot and top is filled.Take a look of the attachment.
Any one with experience with this windings, all explanations and inputs will be wellcommen.
Thanks and regards
Pirulo





RE: Winding Generator
Muthu
www.edison.co.in
RE: Winding Generator
Here a New Attachment
Pirulo
RE: Winding Generator
It's an open slot and looks like a double layer winding, not a single layer winding. The single layer winding machines normally have semi-closed slots. Do you have a winding diagram ? Did the client give these specs ?
Muthu
www.edison.co.in
RE: Winding Generator
fwiw, here's my guess how the winding would be arranged (which is probably obvious for you guys)
4*Atop 4*Btop 4*Ctop 4*Abottom, 4*Bbottom, 4*Cbottom,
That is 12 coils in 24 slots – repeat a total of 6 times.
To get alternating polarity of pole-phase zones, all coils in a given phase would be wound with same polarity (the alternating polarity comes from alternating top and bottom). For the setup given above, A and C would be same polarity, B would be wound with opposite polarity (with respect to line side).
It seems like there is some wasted iron. Why would they design it that way?
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RE: Winding Generator
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RE: Winding Generator
Can´t be double layer because the coils = slots/2, for 12 poles x 3 phases =36 groups and 72 coils/36 = 2 coils per group. The span is 1-10 so the winding could be done.
Usually in one double layer you will have two active coils in each slot but in a single layer we will have only one.
The slot is not 100% filled with the coil maybe some designer use the same iron core for other machines with more output and for this one they used to avoid cost. So the solution was to use a single layer winding.
I never see this kind of design and for it I am requesting all coleagues.
Regards
Pirulo
RE: Winding Generator
I would go for a double layer winding even if the original was single layer with 100& slots used. My $0.02.
Muthu
www.edison.co.in
RE: Winding Generator
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RE: Winding Generator
There are 36 pole-phase zones in either configuration (double-layer or single layer)
Could be single layer with in the format that I described above: 3 May 10 7:40 (72 coils)
Could be double layer with 4 coils per group. Q=4*3*12= 144 coils
The drawing does clearly show two spacers including one wrapped inside the coil which would make it impossible to put two of those coils in a slot... drawing does show single layer.
You said span 1-10 which suggests to me it is double layer.
The previous two facts (spacer and span 1-10) seem inconsisent.
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RE: Winding Generator
Attached you will find all coil specs, maybe the coil drawing will tell more , sorry all in french the costumer request 80 coils for this generator with 144 Slots.
Thanks
Pirulo
RE: Winding Generator
Sure enough, 1-10. Doesn't make any sense to me.
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RE: Winding Generator
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RE: Winding Generator
pirulo - That's not a single layer coil. A single layer coil fills the entire slot and its shape is completely different. It's a double layer coil used only in alternate slots. That's the reason for those fillers. And I've never seen anything like this winding.
Muthu
www.edison.co.in
RE: Winding Generator
You can't make a single layer winding because the pitch is less than full pitch.
You can't make a double layer winding because the spacer wrapped inside the coil prevents you from putting 2 in a slot.
Seems like the options are to change the design toward single layer full pitch or toward double layer without spacer.
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RE: Winding Generator
Muthu
www.edison.co.in
RE: Winding Generator
A - 2 coil sides per slot (in which case the coil as shown on drawing with spacer inside it's groundwall insulation won't fit)
or
B - One coil per slot.. and still called a double layer? (in which case I can't picture what that would look like).
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RE: Winding Generator
A small correction:
There are lots of single-layer windings, which is not made with a full pitch. See simple example in attachment.
Zlatkodo
RE: Winding Generator
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RE: Winding Generator
I guess your winding is one of the following two:
1. - Relatively simple single-layer winding with pitch 1-11. (You need to check the pitch, one more time ).
2. -If you are sure that pitch is 1-10 , yes, this single-layer winding can be done but diagram is more complicated.
I think your statement:
"The slot is not 100% filled with the coil maybe some designer use the same iron core for other machines with more output and for this one they used to avoid cost."
could be correct.
Zlatkodo
RE: Winding Generator
By definition this is a single layer-winding as this particular winding consists of only one layer per slot.
The coils are of the multi-turn coil type (or double-diamond coil type). I assume that this winding is a replacement winding for quite an old generator. The generator utilization factor is pretty low and we have a total of 144 slots x 4 turns per coil = 576 turns. The original winding most likely was a conventional multi-turn coil winding with two layers and either 4 turns per coil with two parallel circuits (giving us 576 turns total) or with 2 turns per coil and one circuit only (giving us also 576 turns total). The latter design would require 10 or 12 parallel strands per turn which would make each turn quite bulky. For easier manufacture I tend to think that the first design was selected originally.
The reason for this unusual replacement winding is quite simple: This French solution cuts the number of coils in half thus saving quite a bit of money. The low generator utilization and the selected current density of about 3 Amps per square mm doesn't require a conventional coil winding with fully filled slots. Especially if the specified loss evaluation is low.
Regards
Wolf
www.hydropower-consult.com
RE: Winding Generator
zlatkodo - on your single layer fractional-pitch-coil wiring diagram... if I draw an end view and try to draw the coil extensions, they have to cross over each other. Has this winding been physically realized? Can you shed any light on how the interference is overcome?
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RE: Winding Generator
The challenge is draw lines to connect the like colors:
A phase
1/2 to 11/12
13/14 to 23/24
B phase
5/6 to 15/16
17/18 to 3/4
C phase
9/10 to 19/20
21/22 to 7/8
At first glance, I don't think it can be done. There are three possible interpretations:
1 - it can be done, I just didn't figure out why.
2 - it can't be done, but somehow there is a difference between my drawing and the physical configuration... I haven't set up the problem right.
3 - it can't be done, and I have set up the problem right... that would mean you can't wind a motor like this. (probably this is the least likely outcome)
What do you think?
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RE: Winding Generator
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RE: Winding Generator
Attached are two rough depictions of what the winding might look like viewed from the end if we stretched it out into a line.
Slide 1 looks like a Herringbone. It requires a lot of moving connection points up and down within the slot.
Slide 2 is a basketweave. It requires two types of curves. I don't think it is realistic since we also have the actual curve of stator circumference which destroys the symmetry of those two types curves.
I guess Herringbone is the best I can come up with. It looks like a challenge to me, but I'm just thinking out loud here.
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RE: Winding Generator
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RE: Winding Generator
http://www.fight-4-truth.com/winding%20jig.jpg
For a semi-closed slot, the coils have a completely different shape and the end windings are in 2 or 3 tiers.
Muthu
www.edison.co.in
RE: Winding Generator
Muthu
www.edison.co.in
RE: Winding Generator
http://ww
Muthu
www.edison.co.in
RE: Winding Generator
pirulo:
You may have noticed that various posts have been received which propably went beyond your original request for information. Your thread originally asked for general information only. In case you still have specific questions, please tell us.
For our information please let us know what the original winding looked like and generator manufacturing date.
Regards
Wolf
www.hydropower-consult.com
RE: Winding Generator
Thanks for the interest, we are a motor repair shop and we was receive the two attached drawings for quote 80 Coils.No more Information.The Alternator is in France But I hope speaking with the costumer we can get the information.
Regards
Pirulo
RE: Winding Generator
Wolf:
Can you give an example description of the physical arrangement for any fractional-pitch lap-wound single-layer winding?
Let's try the one discussed in the original post...
I'll get you started...
144 slots, 12 poles, 3 phases, single layer, 72 coils, coil span 1-10
144slots/(12poles*3phases) = 4 slots per pole-phase zone.
The logical thing to try might be putting coils sides in slots in the following order:
A, A, A, A, B, B, B, B, C
But what comes next? It would have to be A because the span is 1-10. (a complication that doesn't arise in double-layer windings). So where do we put the remaining C coils?
Or is there some alternate creative approach (zlatkodo's) ?
I will look forward to your response, Wolf. Thanks.
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RE: Winding Generator
1 – my questions regarding endwinding layout
2 – how to adapt the approach to coil span 1-11 instead of 1-10.
Thanks again.
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RE: Winding Generator
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RE: Winding Generator
Pete:
As I see it:
Every slot is filled with one coil layer, so we could say we have a single layer winding in front of us. But this statement may be misleading. The double layer diamond coils selected are typical double layer windings. The end winding layout therefore is a conventional one, i.e. no extra tiers/levels/planes are required.
According to the scetch posted 3 May 10 9:58 the diamond coils have 4 turns per coil and a coil span of 1 - 10. Because we have 144 slots and 72 coils, every slot is filled with half a coil. 72 slots are filled with the bottom part of a coil and the other 72 slots are filled with the top part of a coil.
Slot #1 is assumed to accommodate the bottom coil section of coil #1. Therefore, with a coil span of 1 - 10, slot #10 accommodates the top part of coil #1. The next slot to accommodate the bottom part of coil #2 is slot #3 (not slot #2). So, all bottom coil sections are placed in odd slot numbers and the top coil sections are placed in even slot numbers.
Before I go further, let me know what you think.
Regards
Wolf
www.hydropower-consult.com
RE: Winding Generator
I can certainly see that alternating top and bottom coils helps alleviate congestion for a full-pitch single layer winding. However I still don't see how it helps accommodate the fractional coil pitch single layer winding.
Here is my first attempt to lay out what you described:
Slot1 A1bottom
Slot2 A2top (A2bottom was in slot 137)
Slot3 A3bottom
Slot4 A4top (A4bottom was in slot 139)
...
Slot 10 A1top
Slot 11 A5bottom (A5 top will be in 20)
Slot 12 A3top
Slot 13 A6bottom (A6 top will be in 22)
We have at this point two interrelated problems:
1 – The center of the first pole-phase zone is slot 2.5 and the center of 2nd pole-phase zone is 11.5. They do not difffer by a full pole pitch. That doesn't meet the winding objective.
2 – We only have 4 slots in between slot 4 and 10 to fit the pole phase zones for B and C... but we need six. Where are you going to put those last two C phase coils?
Again zlatkodo's approach gets us close. I don't think that's what your describing with alternating upper/lower coil sides in sucessive slots, but I could be wrong.
I would be interested to hear more, especially enough layout to see how the coil pitch is accommodated.
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RE: Winding Generator
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RE: Winding Generator
Zlatkodo
RE: Winding Generator
In attachment you can find more details for three possible types of winding for 12 poles and 144 slots.
In application, each of these three schemes has its advantages and disadvantages and the choice must be made by additional criteria.
Zlatkodo
RE: Winding Generator
I don't see how you can have even numbered pitch like (1-13 or 1-11) in a single layer winding. You can have only odd numbered pitch like (1-10 or 1-12) in a single layer winding.
I have attached a coil placement excel sheet for a 48 slot, 4 pole machine.
The red numbers indicate the slot clashes.
Muthu
www.edison.co.in
RE: Winding Generator
Note that in my previous post it is about 144 slots and 12 poles.
Of course, you can create a single winding for 48 slots and 4 poles with step 1-13 or 1-11.
See my earlier diagram again, for a 24 slot and 2 poles .
After all, how you make single winding for 48 slots and 4 poles? You need to try to draw (no xls, please) how to do it with step 1-12 ?
Zlatkodo
RE: Winding Generator
Muthu
www.edison.co.in
RE: Winding Generator
In zltakodo's 1st powerpoint, we can see for configuration A (1-13 = full pitch) and B (1-11 with 4 coil sides per zone split into groups of 2 with associated coils spanning opposite direction) there is 8 slots available between pole-phase zones to fit the 8 coils sides associated with the other 2 pole phase zones, as required. But for arrangement C (1-10), there are only 7 slots available.... doesn't seem to work. Can you clarify how are you going to get the 8 coil sides from the two other pole phase zones into those 7 slots?
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RE: Winding Generator
In the 1-11 pitch, I used only alternate slots to place the winding. And here you hit the snag at slot no. 11 (which is already occupied by the other side of the coil in slot no. 1).
In both the odd pitches (1-10 and 1-12), you can see there are no such problems. And here too, you have to place coils in every alternate slots only. Sequential placing will not work in single layer.
It's just arithmetic progression actually. :)
Note this is only a problem in single layer winding. Double layer is not a problem unless you use multi-pitch coils.
Muthu
www.edison.co.in
RE: Winding Generator
Winding C also have 8 coil sides in 8 slots.
Please, see the attach.
Zlatkodo
RE: Winding Generator
Considering the only the coil pitch (and not endwinding interference *), I think there is no problem fitting coil sides into slots to produced a balanced winding of the proper pole pitch using the configurations shown by zlatkodo:
7 May 10 2:01 Configuration A for 1-13 (full pitch)
7 May 10 2:01 Configuration B for 1-11
7 May 10 23:47 Configuration C for 1-10 (same as original post)
The three configurations are laid out in attached spreadsheet. I am using Muthu's approach to study only a 4-pole 48 slot machine which tells us everything we need to know (if we repeat it three times we have 12 pole 144 slot machine.)
The first is full pitch coil 1-13. Results in winding factor 0.958 (same as distribution factor... pitch factor = 1). If we try to alternate top/bottom, it doesn't work. We would have tops in odd and bottoms in even, which means we would have a top in both 1 and 13... can't do that. So I just laid it out in simpler fashion where each pole phase zone is all tops or all bottoms.
The 2nd is 1-11. It results in identical identical coil positioning to the 1-13 (just different connections). Therefore as expected the winding factor is the same = 0.958
The 3rd configuration would be applicable to the original post. It results in a lower winding factor 0.892, due to the fact that the coils within a given zone are spread out further.
Note these are all fundamental winding factors (not harmonic winding factors).
* Again this does not consider whether there will be interference in the endwindings. It is a little beyond my ability to know definitevely which arrangements will/won't cause interference.
Muthu – I do not completely understand your objection, but I presume it has to do with endwinding interference. i.e. you reject 1-13 because it cannot be inserted as alternating top/bottom coil sides in sequential slots. I can see alternating is better, but given that the coils resemble 2-layer coils and we can position them near top or bottom of the slot, then I'm not sure it is absolutely required. Is it impossible to fit with all coils within a pole phase zone having same side (top or bottom) in the slot as I have shown in attached?
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RE: Winding Generator
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RE: Winding Generator
LPS for both of you for making me think.
Muthu
www.edison.co.in
RE: Winding Generator
pirulo:
This may also be of interest to you.
Regards
Wolf
www.hydropower-consult.com