Mailing List flyrotary@lancaironline.net Message #63307
From: Steven W. Boese <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Permanent Magnet Backup Generator
Date: Mon, 17 Apr 2017 15:47:45 +0000
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Todd,

That is an impressive effort.

The PM regulators often work by shunting current to ground to limit the voltage.  That means that the maximum amount of heat will be produced in the regulator when the backup system is not being used.  If this is how your regulator works and if the regulator temperature is a problem, it might be useful to investigate the possibility of interrupting the connection between the stator and the regulator to shut the backup system down.  I don't know how high a voltage would result from the open ended stator so this might not be a viable solution.  Of course, the regulator temperature problem may only exist in my imagination.  

Steve Boese

On Apr 17, 2017, at 3:32 AM, Todd Bartrim <flyrotary@lancaironline.net> wrote:

Many years ago we discussed on the list various ways to implement backup electrical sources for our electrically dependent engines. A great amount of discussion was around permanent magnet type of generators. 
   An idea was hatched and discussed, then forgotten. Except I didn't. Some years and a few sleepless nights later I set upon achieving this. Most of the work was done and reported to the list quite a few years back, but at that time I knew I had to set it aside for some time as I had other commitments. 
  At last report I had finalized the mechanical aspect but had made no attempt to integrate it into the electrical system. I've now finalized this and yesterday ran the engine for the first time. Everything worked excellent! So far it seems to have been a tremendous success.
  So I have updated my word document of the procedures for this modification. Including a wiring diagram. 
For your entertainment I've put it on Google Drive in Word format where it can be accessed at the following link
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