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Date: Thu, 24 Feb 2005 13:02:23 -0700
From: Fred Osborn <fosborn@infowest.com>
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To: flyrotary@lancaironline.net
Subject: PM Alternators Disadvantages
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Sorry, I forgot to change the subject when I sent this before so most 
guys just passed
it by. FWIW.

 >Richard Sohn wrote:

 >We should not overlook the disadvantage of PM alternators. At higher 
operating speed,
 >the not used output will have to be dissipated. This is the main 
reason why automotive
 >alternators are regulated by the excitation system.

Another disadvantage of PM devices is the hystersis losses in the stator 
laminations.
At 6000 rpm continuous you could end up with a very warm stator. 
Actually, the ultimate
answer to all this will probably be a switched reluctance integrated 
starter/alternator.
Used with an EWP - no belts at all.

Fred Osborn