Results: Starting a Teletype sync motor question

• To: tesla-at-pupman-dot-com
• Subject: Results: Starting a Teletype sync motor question
• From: FutureT-at-aol-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
• Date: Mon, 07 Jun 1999 17:14:08 -0600
• Approved: twftesla-at-uswest-dot-net
• Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Gary, Reinhard, Bart, Ed, Malcolm, David, all,

Thanks to all above and anyone else who gave suggestions for
solving the motor starting conundrum.  It turns out that the 
technique that Gary Lau suggested seems to be the best one for
this motor.  After installing a 100uF cap, the motor started smoothly
with no clattering, and with good torque.  The cap has to be 
disconnected after the speed ramps up to prevent overheating of the
start winding.  This fits in with what Gary said about the cap being 
physically small (electrolytic I would assume.  I've seen electrolytics
marked in a voltage range, as others have also mentioned).  (I assume
that an electrolytic cap would not be intended to remain in
the circuit as a run cap, but would be intended only for starting.)
By the way, a 75uF cap started it smoothly, but not in all positions.

This motor is marked; single phase, 120 VAC.  There are 4 wires;
red, blue, yellow, and green (ground).  I have another smaller 
teletype sync motor, and it has the same color wires, so I assume
that they are to be hooked up the same way.  This smaller motor 
has a cap and an external potential relay that kicks out the cap 
after the speed ramps up.  I can't read the cap value without
dismantling lots of brackets, etc.  

It would seem that the smaller motor, and the 1/12th HP motor,
and Gary's motor, are basically of the same teletype ilk.  In any
case, a separate push button switch will be used to connect the
cap for starting, just to simplify things.  The motor now meets all
needs and hopes, thanks again.

Cheers,
John Freau

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