Re: Starting a Teletype sync motor question

Hi John,

Without the correct value run cap (not necessarily a start cap), the start up
and run modes can be greatly thrown off. They can also run in an oscillatory
mode. I'm not sure of the exact motor your using, but I think a call to the
manufacturer will clear up all doubt and put you right in line with what cap
size which should be used (or other method) for the motor. Tech Support for
this type of info is usually pretty good because the company probably uses
reduntant design (same motor's - different cap) in applications to cut
product costs. I would recommend checking with them if no one on the list has
a definitive answer.


Tesla List wrote:

> Original Poster: FutureT-at-aol-dot-com
> All,
> I'm using a 50Hz, 3000rpm 1/12th HP Teletype sync motor on 60Hz,
> for 3600rpm in a rotary sync gap.  I tried connecting a 7uF to 30uF,
> cap across the blue and red wire for starting, but it won't start this
> way.  Yellow and blue are connected to the line.  I then touched the
> red and blue wire together with no cap for starting, this works better,
> but the motor still often needs a push to get going, and it makes
> clanking noises as the speed ramps up.  Once it reaches max
> speed, I disconnect the red wire, then it locks up fine.  I've been
> using this rather awkward method for starting it.
> I realize that Teletype motors usually use an external relay block
> for starting, but different motors seem to be wired a little differently?
> I wonder if the 60Hz on a 50Hz motor makes the starting a little
> more difficult?
> Does anyone have any suggestions or knowledge of the correct
> way to start this type of motor?  Or maybe the motor has an internal
> defect?
> Thanks,
> John Freau