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Re: Remote phase cntrl


>
> Original Poster: "Robin Copini" <rcopini-at-merlin-dot-net.au> 
>  

Hi Robin, 
It looks as though the amount of phase shift is very small - maybe 10 degrees? 
Is this about what you observed or am I reading the phase shift incorrectly? 
Also, since your using a 1HP motor, it should have significant torque and I
think will do much better than smaller motors commonly used that will have a
harder time at lower input voltages. They will most likely even have a smaller
degree of phase shift capability. 

Bart 
>
>   
> 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