Skip Pole Help

[marv]

I'm ready to wire my laminated stator using the skip pole technique.

Which might reduce some growl and vibrations. Zubbly described it

briefly in a earlier post but I couldn't quite grasp it.

(It's for a 3 phase, 12 pole, with #16 wire) 22" stator

Here's a picture of where I'm at now.





(the longer this takes, the more things change)

thanks Marv.

[Nando]

How many turns per coil and why Skip Pole technique ?.

Nando

[zubbly]

hi Marv!

looks like a fantastic job.

just need to confirm a few things with you first.

aside from skip pole, how many circuits do you wish in the connection?, or what did you design it for (1 star?  2 star, 3 star, 1 delta?, 2 delta, # delta?)

confirm how many stator slots

confirm how many coils

confirm coil span (slot 1 and?)

confirm how many mags on rotor and polarity pattern

do you wish to have sufficient leads so that you can make it star/delta and more than one circuit?

skip pole is "not" a must for a high pole count stator, but if your design was to produce a lot of electrical noise (only way to find out is to use a standard connection and find out) connecting it skip pole to start with will serve to make for quieter operation.

i may have some more questions for you depending on what answers you give me.

zubbly

[marv]

Hi Zubbly;    I just want to hook this up in star, one circit.

with NO star/delta switch.

72. stator slots,36 coils, one coil span= slot 1 & slot 4
    
24. mags 2"x2"x1/2"  + - + - + - etc.
    
    

this unit had lots of noise and vibrations before, so this might

be the way to settle things down some.

Hope this discription helps.

thanks Marv.

Nando; the coils have 95turns of #16 wire.

[zubbly]

Marv,

you really have a 24 pole machine there.

do you want to connect for 24 pole?

zubbly

[marv]

Zubbly;  I thought when I have 36 coils and 12 coils in each phase, that

is a 12 pole?

What do you think is the best way to connect it then?

Marv.

[zubbly]

hi again Marv,

kinda wish you had asked me a little earlier before you wound the stator.

just to state a few facts.  12 coils per phase can be connected consequent pole (producing 2 poles per coil. it was called "phantom" pole a long time ago).

12 coils per phase can also be connected series pole, which will produce 1 pole per coil.

in order to be 12 pole, or 24 pole, the proper coil spans must be done.

the effective coil span for 12 pole would be 72 slots divided by the number of poles you want. so 72 divided by 12 equals equals 6 ( plus 1 for full span or coil span of 1-7). basically, a coil span of slot 1 and 6 can be used or slot 1 and 7.

for a 24 pole machine, the effective coil span is 72 slot divided by 24 equals a coil span of slot 1 and 3 (plus 1 for full span of slot 1 and 4.  which you have). if you wanted to use coil span of 1-3, you would have to use 2 coil sides per slot, and 72 coils.

you have 24 mags on the rotor. assuming they are equaly spaced, and they alternate N S N S N S, you have a 24 pole rotor.

if you wish to use the 24 mags as a 12 pole unit, you would have to group the mags in 2's tight together of the same polarity in order to make a 12 pole rotor. you then would also have to rewind the stator with a coil span of slots 1 and 6 or 7 in order to best match the width of the magnet pole between the coil legs of the coil.

what you have now, is what i really would have selected to do myself with a 72 slot stator. 24 pole machine. it will give you 60HZ at 300 rpm. you could probably transform the output to what you want at 200 rpm (40 HZ).

so i can give you a numbering system to connect for 24 pole if you still want it. skip pole may not be possible with the consequent 24 pole connection (i will have to figure that out to be sure). so please let me know how you wish to procede. it will take me a day or 2 to do it for you with the new year holiday here.

on another note, just curious how you arrived at the number of turns you have per coil. what voltage are you expecting from the machine and at what rpm?. what is your expected output and how will you be using it.

the laminations look skewed.  am i correct?  and also how did you make the stator?  you did an awsum job.

zubbly

[willib]

Hey Mr Zubbly , what if he used 1"X 2" mags?

36 poles

would that work?

it would be a shame to dissassemble that nice piece of work Marv

thanks for the glimpse of your work

[Flux]

Marv

I suspect that whatever way you wind it you may still find it noisy. The axial construction is not as rigid as a radial design and the magnet rotor plate may well vibrate in a lot of modes. The stator may also do this, depending on how it is supported.

I am not familiar with Zubbly's skip pole winding, but certainly on big radial machines, there are slot/pole combinations that are noisy. I suspect the resonance modes on an axial are totally different but it may still help.

As it stands you have a 24 pole winding with an even number of coils per phase. If you series connect them, I don't think the order in which you connect them will have any effect. I think you would not be wise to try and use it for any other pole number for the existing winding just to try to reduce noise ( which you likely won't do ).

Superb work, I am sure it will work fine.

Flux

[tecker]

  You do have to expect vibration with axial machines in general as the repulsion or attraction go to work on the bearings .The best way to smooth that out is to skew the magnets there by giving an lessening pole collision while getting the duration .Maybe try to keep the rpms up to give more inertia in the rotor and Skew Zubbly style to get the vibration down and improve your pole coverage .

[Nando]

Marv:

Blade size and length ?.

What is the Peak Power that You are expecting from your new 72 slots generator ?.

What is the expected peak voltage at peak RPM ?.

What is the use for the wind mill.

Nando

[marv]

Hi Zubbly; Good eye! yes the laminations are skewed.

If you could give me a numbering system to connect for 24 pole

I would appreciate it.

This machine will be run with a grid-tie inverter using mppt 50-500vdc input

at 60-250rpm.

thanks for the help

Marv.

[zubbly]

hi Marv,

here is a diagram and numbering system that will easily let you connect it. you can connect it consequent-adjacent pole (standard way) or consequent-skip pole.

skip pole will only serve to make it electrically quieter, not vibration quieter.

i posted a diagram in the irc gallery.

http://www.anotherpower.com/gallery/zubbly/24poleconnections

if you need more help or don't understand what i have drawn, just ask me.

zubbly

[marv]

Thanks Zubbly!    One more thing, I have used phase insulator tape

 between the coils. Is there anything special to do to insulate

between phases when connecting coil wires?

 It is a high voltage machine, so this might be an issue.

(I will also be epoxing or bake varnishing the stator)

Marv.

[zubbly]

hi Marv,

good decision on using phase tape between coils.

as in motor rewinds of higher voltage, we normally use "sleeving" or some call it spaghetti slid over the coil end wires to where they meet for soldering. after soldering, it is taped and then sleeved with a little larger sleeving. this sleeving prevents phase shorting as the coil end wires end up laying across all 3 phases. you can obtain it from motor repair shops. it is generally white in colour.

here you can see the sleeving on my 7.5hp conversion just before wires are soldered.

http://www.anotherpower.com/gallery/zubbly/7_5bldw14

hope this helps.

zubbly

[marv]

Hi Zubbly; Yes I have seen that sleeving before, thanks!

On your skip pole diagram, why does the coil connection jump from

#22 to #3 ?

It looks like the logical progresion to go from #24 to #3

then leave #22 and #1 for the lead wires.

Marv.

[zubbly]

hi Marv,

it does look a bit strange, but this must be done in order to carry on the circuit and maintain a skip pole.

#1 is the beginning of the phase and #24 is the end of the phase. if you were to draw out one complete phase and connect as suggested, you will also find that there is one place where 2 coil groups are skipped rather than 1. it is strange, but necessary in order to maintain the skip pole.

to prove it to yourself, connect and solder one phase only. then use a low voltage DC source and connect to that one phase. then take a compass close to the laminate face and slowly go around the whole unit marking with chalk the exact position and polarity.

you will see that it alternates N S N S N S.

if you have any doubt, use the consequent-adjacent diagram. remember, the only purpose skip pole will serve is to make it more electrically quiet (it may not be electrically noisy even with the standard consequent-adjacent pole connection).

zubbly