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Forum Index : Windmills : decogging power drops

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dazz
Regular Member

Joined: 15/04/2008
Location:
Posts: 78

Posted: 04:07pm 14 Apr 2008

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Hi All,
I'm just wondering whether anyone knows from experience, or tests, what the performance drop is between say an 80SP and decogged 80SP in terms of maximum power output?
Also, has anybody replaced an 80SP with a 7 phase setup and noticed the power difference?

cheers, Daryl

herbnz

Senior Member

Joined: 18/02/2007
Location: New Zealand
Posts: 258

Posted: 07:37pm 14 Apr 2008

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Hi Daryl

My present setup for testing on my lathe is limited in testing up to Maximum power but up to 800 watts The efficiency of decogging via rounding of the poles shows an average of 8.9% drop.
Twisting the poles shows a 2% drop.
7 Phase is outside my experiance
My present plans are to use a larger Dc drive motor on a old saw bench to allow testing to greater power levels, but at present motor has been diverted to a pile driver for builting a jetty.
So testing FP on the back burner

Herb

Gizmo

Admin Group

Joined: 05/06/2004
Location: Australia
Posts: 5116

Posted: 09:13pm 14 Apr 2008

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My basic tests with 7 phase show a slight power increase, but this is based on testing up on the tower, not very scientific. I think its the same as 3 phase is more efficient than single phase, less dips between the peaks. So a 7 phase should be slightly more efficient again, remembering that the stator isn't decoged in a 7 phase conversion.

Glenn

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dazz
Regular Member

Joined: 15/04/2008
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Posts: 78

Posted: 09:49pm 14 Apr 2008

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Thanks guys!

Glenn, thats a big plus for the 7 phase conversion!
Is that increase across the range of low to high RPM do you think, or more pronounced at one end or the other?

Also how do you go in low wind start up with the 7 phase. I mean i know the lack of cogging allows for a lower start up speed, but have you noticed how low? Is it like the 15km/h or so with a decogged 80SP?

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