Re: ARSG Motors (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Mon, 27 Aug 2007 17:55:01 EDT
From: FutureT@xxxxxxx
To: tesla@xxxxxxxxxx
Subject: Re: ARSG Motors (fwd)

In a message dated 8/27/2007 9:22:12 A.M. US Eastern Standard Time,  
tesla@xxxxxxxxxx writes:

So for those of you who run ARSG's, my question is   this:
>    If we make such a big deal out of phasing for   SRSG's, then obviously 
>phasing at (at least) the synchronous speeds  is  important. Have you guys 
noticed 
>a performance change when  sweeping through the  synchronous speeds, or when 
>setting to a  synchronous speed, depending on the  arbitrary phase 
relationship? 
Phil,
 
Generally with an asrsg when it nears the sync speed, the coil starts  to
surge (pulse with long and short sparks alternately at a rate depending on 
the exact speed).  Normally no one runs it at such speeds because  it
can be bad for the caps.  We avoid those speeds and don't linger  there.
It's just about impossible to achieve any phase control at sync  speeds
with an asrsg.  The speed cannot be held constant.  Using an  electronic
controller, then yes the asrsg can be made to run in sync with proper
phasing as some folks have done.  When running further from sync
speeds, the asrsg's just fire hit or miss on the ac waveform, and you
choose your speed, and get what you get, spark-wise.  There is  no
fiddling needed provided you avoid the sync-speeds.  Spark  appearance
and length may vary with speed to some degree.  Usually motors  are
not so powerful that they can shock the rotor at start up.   

John
 
 


>Do you sometimes have to come off synchronous a  tad, then  return to it to 
>"hunt" for a particular "sweet spot" in the  phase  relationship?  
>    Does anybody run a  "phase control" or do phase  adjustments with an 
ARSG? 
>Does it  make a performance difference? 
>    Or does running an ARSG  just give you "beats" of  good performance, and 
>it takes a bit of  fiddling to obtain and maintain a "good"  setting?
> 
>   I'm following Bart's lead by putting together a  3-ph VFD setup  for my 
>RSG. I already had a 3/4 hp single-phase motor I modified   for a SRSG, but 
so 
>many folks advocate the ARSG for pig setups that I  figured  I'd give it a 
try. I 
>think another important advantage  is the control over  the motor's accel to 
>speed, so as not to  mechanically shock the rotor system  when starting up.
>  
>    Thanks!
> 
> 
>-Phil  LaBudde






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