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Re: Remote phase cntrl



At 09:50 PM 03/27/2000 +0100, you wrote:
>Hi Jeff, coilers,
>
>I'm glad the phase adjust thing works well for you.  I think the degree of
>phase adjustment available depends on the locking margin of the motor to
>start with.
>
>If the motor is barely holding the disc in sync,  then it's already
>lagging by a lot of degrees and you really haven't got much to play with
>before it starts hunting.  If the motor is really powerful,  then it will 
>lock spot on at full voltage and you should be able to introduce a lot
>more phase lag with the Variac before it starts hunting.
>
>I think this is a good reason to use motors with ample power for sync
>rotaries.  We really don't want the rotary phase to shift if the line
>voltage drops when drawing a lot of power !
>
>A few people Emailed me and said that they didn't get good results with
>this remote control method,  so it doesn't work for everyone :-(
>
>							Cheers,
>
>							-Richie,

I would think that you would need a motor with plenty of extra power
available and also have a rotor with a fair amount of drag.  Thus, you
would have the motor doing a lot of pulling the dragging rotor at full
power and the motor would still be able to drag the rotor with much more
shift at lower power.  The variac would also reduce the current draw of the
motor allowing cooler operation in many cases.  

A caution may be if the AC line sags or there is a voltage fluctuation that
may cause the motor to fall out of sync which may be "bad" in some cases.
Normally, the momentum would cover this, but if you were on the edge of
sync the motor may not return.

Cheers,

	Terry


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