Re: Synch motor Phase controller question

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 12/13/02 6:18:21 PM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:


>John,
>
>I'm still not following what exactly you mean by a max of 5V increase across
>the motor at the variac position which
>gives the highest voltage across the motor.
>
>Do you mean select a capacitor so that I can vary the motor voltage via the
>variac so for example:
>At full clockwise I would get say 120VAC
>And at full counterclockwise I would get say 125VAC????
>
>Thanks
>
>Dan


Dan,

No, what I mean is select a capacitor which gives a five volt
rise over the line voltage across the motor at the setting of the variac
which gives the highest voltage across the motor.  This variac
dial setting will be where ever it happens to be to give the max
voltage.  Just turn the variac dial gradually and watch the voltage
across the motor.  At some point along the dial, the motor voltage
will peak then begin to fall again (if you have a large enough
capacitor installed).  At the peak voltage, the voltage
should be 5 volts over the line voltage.  Of course it doesn't have
to be exactly 5 volts as I explained in my prior posting.  Be sure
to have the variac at a zero inductance setting when you begin.

In reality, the main thing is that you get a sufficient phase-adjustment
range without over-volting the motor too much.  The 5 V thing is
just a guide.

It may become clearer if you build it and play with it a little.

John