more tests: John Freau's SRSG Phase Controller

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

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

All,

I decided to do a test to gauge the effect of very small changes in
cap value for the phase shifter circuit.  I used the 1/20HP sync motor.

   cap uF        reso-rise over line
      50                   10  volts
      47                    5 volts
      46                    3 volts
      44       no reso-rise, but loses lock at full variac L position

The best values above are the 46 or 47uF values.  It can be seen
from these results, that the cap value is quite critical if it's desired
to keep the reso-rise limited to about 3 to 5 volts.  The cap value
must be precise within a few percent.  A 10 volt reso-rise can be
tolerated however.  When a cap is selected, a voltage test should
always be performed, to verify that the reso-rise does not exceed
10 volts across the motor, as the variac is slowly adjusted through
its range.  I prefer to keep the reso-rise limited to 5 volts.

In the above test, the 44uF cap value works OK, and gives the full
phase shift, provided the variac is not turned quite fully to the end of 
its range.  This is an intriquing arrangement because there is no
reso-rise at all with the motor in place.

John Freau