2 pole winding with "12 groups"

[petronila]

Dear All,

There are some OEM that designs 2 pole motor using 12 groups rather than 6 groups and connecting in series one group with the inmediatelly adjacent group forming a group with the double of coils, (i.e. 2 pole-36 slots with 12 groups of 3 coils pitch 1-14,16,18).

Can somebody share a layout/winding diagram for this kind of arrangment?

Thanks in advance

Petronila

 

[mtrgen]

It would seem that this is a winding configuration that splits the groups in half. (phase insulation in between the first 3 groups)

I have experienced this system a few times depending on HP range.

 

[electricpete]

> connecting in series one group with the inmediatelly adjacent group

You know more about this stuff than me so I'm probably missing something, but why would you consider that two groups instead of one large group?

Another way of saying it: how would this 12-group motor with two series 3-coil groups per pole-phase-group differ from a 6-group motor with one 6-coil group per pole-phase group?

=====================================
(2B)+(2B)' ?

 

[petronila]

mtrgen,

What you are describing is not what I am talking about, you are describing insulation in the middle of the group. You should install insulation in the middle of the groups in random winding where 80 ≤ volt/coils ≤ 100. If volts/coil exceeds 100 is advisable to insulate all coils. This insulation extra is to avoid insulation damage due to high voltage stress.

Pete,

The OEM uses two groups in series instead of a larger group because production matters because it will more difficult to install a larger coil with an automatic machine. i.e. Same case of the concentric winding, 2 poles, 36 slots, 12 groups of 3 coils (2 sets of groups connected in series) with a pitch 1-14,16,18. You will form a larger group with one group with pitch 1-14,16,18 in series with a group with pitch 1-14,16,18. If you design the winding with 6 groups of six your group should be usually 1-8,10,12,14,16,18 pitch or 1-5,7,9,11,13,15 pitch and the automatic inserting machine configuration will be completely different.This same coil installation process applies also to manual rewind.

Petronila

 

[electricpete]

thanks petronlia. I'm only familiar with simple lap windings. I saw you said coil pitch 1-14,16,18 but I thought you meant pick just one option from 14/16/18. It's over my head when you start talking about different coil spans in the same winding, like concentric. So I didn't fully understand your response, but it's enough for me.

=====================================
(2B)+(2B)' ?

 

[zlatkodo]

Hi, Petronila,
Easier production is not the main reason for this type of winding, especially if it is about parallel connection (2 Circuits).
Such a diagram has been available on our website for a long time.
Look for the title : [highlight #FCE94F]2 Pole Winding with 2 Circuits, unusual but commonly used...[/highlight]
Regards
ACW

 

[petronila]

Thanks Zlatkodo,

If easier production is not the main reason just let us know your thoughts about it. The 12 G-2 pole connection can be avoided redesigning the winding to 6 groups-lap, that works all the time. However, if somebody wants to keep the same 12 G 2 Y-D redesing can use the attached winding diagram as a guideline.

Petronila

 

[zlatkodo]

Hi, Petronila,
Your drawing shows the standard winding layout.
But in large motors very often a special internal connection is applied.
This is some kind of skip interleaved connection, that significantly reduces motor vibrations and increases the lifespan of bearings and motor.
Regards
ACW

 

[petronila]

Hi zlatkodo,

Thanks for the inputs. Just note that my post is not refering to interleaved or interspersed windings I was asking for a 12 G in series forming 6 groups not a sort of special connection intended to reduce harmonics and to avoid negative-sequence that try to rotate the motor in oppossite directions (negative torques).

Petronila

 

[zlatkodo]

In that case the diagram is very simple and you know it for sure.
Please see an attached file.

 

[edison123]

Using two groups of 3 coils gives 15% higher pitch factor than using single group of 6 coils. Which means 15% lesser turns and hence 15% higher ampacity (in theory anyways).

Also, using two groups halves the coil formers, 3 vs 6 formers.

You can also interleave the two groups for better harmonics reduction.

Muthu

http://www.edison.co.in

 

[zlatkodo]

Hi, Muthu,
Just small correction:
Winding factor is the same for both cases if you don't change the pitch.
- 2 groups of 3 coils with pitch 1-18; 2-17; 3-16
- 1 group of 6 coils with pitch 1-21; 2-20; 3-19; 4-18; 5-17; 6-16.
For both cases the winding factor is 0,923563.

 

[edison123]

Hi zlatkodo

My calculations are based on petronila's 1-14,16,18 and 1-8,10,12,14,16,18 pitches.

Muthu

http://www.edison.co.in