Winding Generator 3

[pirulo]

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

 

[zlatkodo]

Muthu,
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

 

[edison123]

You can start the winding (yours show only the start of the winding) but after certain coils, you cannot proceed further. You can try that neat PPT of yours with more coils if you feel like. I am not that good with PPT.

Muthu

http://www.edison.co.in

 

[electricpete]

Interesting stuff.

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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[edison123]

pete - My excel file shows the coil placement sequence. For example, in the 1-13 full pitch columns, you start with the one side of coil in slot 1 and the other side of the coil lies in slot 13. The you place the next coil in slot 2 and slot 14. You can proceed this way up to slot no. 12. The problem starts at slot no. 13 since it is already occupied by the other side of the coil in slot no. 1 and hence my red highlight.

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

http://www.edison.co.in

 

[zlatkodo]

Electricpete,
Winding C also have 8 coil sides in 8 slots.
Please, see the attach.
Zlatkodo

 

[electricpete]

Thanks zlatkodo. I vote you a LPS for that.

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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[electricpete]

Clarification in bold:

The 2nd is 1-11. It results in identical current distribution in the slot section same as the 1-13 (just different coil arrangement).

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[edison123]

Thanks pete and zlatkodo. Yesterday, I went back and redid my excel. And arrived at the same configuration as you guys. One lives and learns.

LPS for both of you for making me think.

Muthu

http://www.edison.co.in

 

[wolf39]

pirulo:

This may also be of interest to you.

Regards

Wolf
www.hydropower-consult.com