D.C. pumps and motors... [RE-wrenches]

[Windy Dankoff, Dankoff Solar]

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>Steve...
>
>Thanks for the response.
>
>As I suspected the DC option wins every time if the issue is only efficiency.
>
>Now to the second part of my question...
>Some DC motor manufacturers are closing down. Apart from getting a motor that
>might be specifically designed for a fork lift or a golf cart where 
>can one get
>a supply of DC motors ??

There are numerous makers in US. Most carry little stock and depend 
on OEM (original equipment manufacturer) orders for quantities. The 
leading stocking manufacturer is Leeson Electric. We buy from them on 
an OEM basis for use with some of our surface pumps, and we also get 
some non-stock motors custom-made. We can sell them at dealer prices 
to you.

>Typically my clients demand energy efficiency and luxury. They are often
>wealthy green professionals who have escaped from the US and want heaven in
>clean green NZ.
>They typically want large pools that require lots of pumping. Commonly these
>pumps will draw about 2.5 kW AC

See our SunCentric pump line, and articles on pool pumping at our web 
site, reference section. The articles describe how to reduce the 
pressure requirement of the pumping system to compound the energy 
saving that the DC pump will provide.

>As I normally use a 48 Volt battery bank I would like to run the pool pumps
>with 48 Volt DC motors but have found them hard to obtain.

We get them made for us for our pumps. You can look at our site and 
contact me off-line for details.

DC pumps, optimally selected, will frequently use less than half the 
energy of AC pump/inverter. Any pump that runs for long portions of 
the day will be more economical on DC.

>
>As a second option, is there a controller available that will reduce the power
>requirement of an AC motor after start-up ?? I have heard of such a unit being
>developed but nothing concrete.

Available gadgets are only effective on motors that are underloaded. 
Doesn't apply to centrifugal pumps, normally, because they push the 
motor to capacity by design.

Windy
-- 

Windy Dankoff
    Founder
    Vice President, Technical Development & Training
    Direct e-mail: windy at dankoffsolar.com

Dankoff Solar Products, Inc.
    Wholesale distributor of solar equipment
    Manufacturer & importer of solar water pumps

2810 Industrial Rd.
Santa Fe, NM  87505  USA
(505) 473-3800    FAX  (505) 473-3830
E-mail:	  info at dankoffsolar.com

SEE OUR INFORMATIVE WEB SITE AT:
http://www.dankoffsolar.com

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