Author Topic: Delta/Double delta winding  (Read 17927 times)

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(unknown)

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Delta/Double delta winding
« on: August 25, 2008, 02:54:40 PM »
I have a problem with an AC motor with delta/double delta switch, 36 slots,  6 coils, 6 leads,  2900 rpm.,at 50Hz. What I'm looking for is winding diagrams of this type of connection or helpful information about this problem. Any help would be greatly appreciated.

Viktor
« Last Edit: August 25, 2008, 02:54:40 PM by (unknown) »

SparWeb

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Re: Delta/Double delta winding
« Reply #1 on: August 25, 2008, 09:07:08 AM »
If you read among recent posts, Flux has given some advice about european-style motors and their internal connections that will help you, too.  This is the link:

http://www.fieldlines.com/story/2008/8/24/10236/8884


 Here is a diagram that I made to get things straight in my head.

It is not perfect for you, because european motors probably have different wire numbers (they might go U1, V1, U2, V2, etc., but I can't remember for sure).

« Last Edit: August 25, 2008, 09:07:08 AM by (unknown) »
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Flux

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Re: Delta/Double delta winding
« Reply #2 on: August 25, 2008, 09:19:39 AM »
If you have 6 leads then I assume it is the conventional star/ delta European arrangement. I don't know what you mean by double delta that is a new one to me. To do parallel delta I think you would need more than 6 leads.


As you give no idea of your problem it is impossible to help.


Flux

« Last Edit: August 25, 2008, 09:19:39 AM by (unknown) »

(unknown)

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Re: Delta/Double delta winding
« Reply #3 on: August 25, 2008, 10:37:41 AM »
SparWeb,

Are you sure this diagram is for 2 pole groups because in my opinion it is for 4 pole groups?


The problem is that this motor is for repairing and it was brought with completely damaged leads and nothing could be seen. I'm sure the leads are 6 and it has to be with the double delta connection which is more used in American system. What I can't do is to arrenge the coils.


This is the original application manual for the motor

http://img143.imageshack.us/my.php?image=dvoentkyt9.jpg


And this explains as a whole very good the double delta winding

http://www.usmotors.com/Products/ProFacts/1-120-8.htm

« Last Edit: August 25, 2008, 10:37:41 AM by (unknown) »

Flux

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Re: Delta/Double delta winding
« Reply #4 on: August 25, 2008, 11:06:11 AM »
From that information the windings have 12 leads but they are pre connected as delta. The centre points are brought out and you parallel them externally.


The scheme is similar to star delta for reduced current starting but it is a series parallel arrangement with a 2:1 step and not 1.7:1 for star delta.


If the leads are missing you will have to find the 12 coil group leads. It is a 2 pole winding so you will most likely have 2 coils per pole in series if it is fully wound. If it is coincident pole there will be one coil per pole per winding.


When you have found your 6 coils with 12 ends then you can arrange the delta to 3 outside leads and bring out the centre to the other 3.


It seems European manufacture and if aimed at the N American market it would have been 60Hz. For Europe I can't see why they didn't just use star/delta. It looks as though they supplied both options. The delta/parallel delta would take marginally less starting current compared with star delta but the change over current would be greater.


I don't have any specific diagrams but unless something drastic has happened you should be able to get back to the original 6 coils with 12 leads even if the linking wires has been messed about with.


Flux

« Last Edit: August 25, 2008, 11:06:11 AM by (unknown) »

(unknown)

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Re: Delta/Double delta winding
« Reply #5 on: August 25, 2008, 12:05:53 PM »
So I'm doing exactly as you say but the starting current is very high so I suppose my mistake is in the "first" delta - I can't arrange the poles properly. That's why I'm looking for some winding diagrams.


Thanks in advance.

Viktor

« Last Edit: August 25, 2008, 12:05:53 PM by (unknown) »

TomW

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Re: Delta/Double delta winding
« Reply #6 on: August 25, 2008, 12:26:23 PM »
Victor;



So I'm doing exactly as you say but the starting current is very high so I suppose my mistake is in the "first" delta


Not sure how this is topical here. We are not really a "motor repair" forum.


Doesn't sound like you are building it into an alternator but trying to repair it?


We have to draw the line someplace.


Tom

« Last Edit: August 25, 2008, 12:26:23 PM by (unknown) »

(unknown)

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Re: Delta/Double delta winding
« Reply #7 on: August 25, 2008, 12:35:05 PM »
Thank you Flux and Steven.
« Last Edit: August 25, 2008, 12:35:05 PM by (unknown) »

Flux

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Re: Delta/Double delta winding
« Reply #8 on: August 25, 2008, 12:39:30 PM »
Nearly impossible to help without seeing the type of winding.


You effectively have two 3 phase windings, each is 2 pole. Each winding on its own should run correctly but the current rating will only be half so you cant run it at full load continuously but you should be able to run it light on each winding connected in delta. If you can get that far then you are well on the way to being able to series connect the 2 windings and then your starting current should drop well down over that of a single winding.


The awkward bit is to do the parallel connections such that the windings are still in phase.


If you look up typical 2 pole winding diagrams you should easily be able to see if the thing is consequent pole or a 2 layer winding. Somehow you need to identify the 2 individual coils for each phase per pole. They may be wound in the same slots, adjacent slots or with a consequent pole you may have 2 machines wound in there as mirror images.


I would have thought it would be easy to distinguish the phases because of the coil displacement, having sorted the phases then you should be able to see how the duplicate coils are fitted in.


I think that if you can get it running as a parallel delta with a pair of leads for each phase then it would start equally well in star and that would be simpler to puzzle out.


Flux

« Last Edit: August 25, 2008, 12:39:30 PM by (unknown) »