[AT] More On Electric Motors

[Alan Riley]

Charles, the switch does not have to be internal to the motor.  An
external adjustable time delay relay works fine.  The delay should
be set such that the motor has time to come up to speed under
load before the transfer from the start winding to the run winding
is made.

Alan  




----- Original Message ----- 
From: "Sheppard, Charles E" <sheppard at indiana.edu>
To: <at at lists.antique-tractor.com>
Sent: Tuesday, January 24, 2006 2:43 PM
Subject: [AT] More On Electric Motors


I agree with the comments about the older motors being better.  Not only
did they have a higher Service Factor, but they were heavier, e.g. cast
iron instead of die-cast aluminum.  I have several old 1 hp. motors that
are bad because the centrifugal switch that disengages the starting
windings failed.  Somewhere I remember reading about a relay that can
start a single phase motor.  I think they were used on older
refrigeration compressors.  I suspect they engage the START winding for
a few seconds to get the rotor turning.  Anybody know about these and
where I might be able to get them?

 

On the discussion recently about three-phase motors:  I have seen many
articles about making a rotary converter from an old three phase motor
that "idles" in the circuit.  There are several ways to get this motor
turning initially like a single phase motor that can be disconnected.
The idler motor must be at least equal to the largest motor intended for
use (I think).  My question:  Can power be extracted from the three
phase idler motor?  The static converters use some sort of capacitors to
make a three phase motor run so it seems possible that you could use
capacitors to get the idler motor going and use it to power something
while serving as a rotary converter, too.

 

 

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