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Re: Remote phase cntrl

Hi All, 

 I have recently completed my new srsg with a variac for phase control. I took
some photo's of the incoming waveform along 
with the 'cut' point the srsg is on at the given variac set-point. The motor is
a 1hp 1500 rpm unit with a 250mm g10 
disk with 8 electrodes. take a look at 

 www.geocities-dot-com/rcopini/srsgsetup.html 

Looking at the minimum vs maximum photos you can see the amount 
of phase change achievable using this method. 

Best Regards 

Robin Copini. 
  
  

Tesla List wrote: 
>
> Original Poster: Terry Fritz <twftesla-at-uswest-dot-net> 
>
> 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