Re: more tests: John Freau's SRSG Phase Controller

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

Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi John,

Very interesting and a great way to test and fine tune the needed cap size!

Are you using "true RMS" or "scaled rectified peak" AC meters?

Cheers,
	
	Terry


At 09:01 AM 12/21/2000 -0500, you wrote:
>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
>