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Re: About this phase shifter
Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <FutureT-at-aol-dot-com>
In a message dated 2/18/01 3:44:07 PM Eastern Standard Time, tesla-at-pupman-dot-com
> Original poster: "Tyler Steineckert by way of Terry Fritz <twftesla-at-uswest.
> net>" <tsgeoman-at-qwest-dot-net>
> I have a 1/30hp motor that has a start cap. Can I still use this design
> phase shifting? Also, I use a variac to increase the voltage to the point
> that the motor will lock sync. Because the motor is a little small and the
> roto is large and heavy. It will lock at 128 volts, then I can bring it
> down, even to 65 volts and it will stay locked. How can I use the phase
> shifter and still be able to raise the voltage of the motor to 130 so that
> it will lock?
> Thank you all
Yes, you can use a cap start motor. Just hook it up normally
according to the phase shifter circuit. Select a phase shift cap
size by trial and error so that it gives 130 volts at some point
on the phase variac knob. This way, the motor will start without
using the voltage variac you're using now. You'll need only the
phase shift variac and cap. In use, before you apply power to
the motor, set the phase variac to the position that gives 130
volts, and the motor will start when you apply power.
Set the mechanical phase of the sync gap, so the coil will
be phased up well when the variac is not at the 130 volt
position, this will keep the motor voltage lower during operation
so it runs cooler.