Re: [TCML] VFD motor

[ashumate3@xxxxxxx]

VFD’s  are cool in that they convert 3 phase AC to a DC voltage that is 
reprocessed to  variable frequency for speed control of AC motors. This of course 
is hurting  manufacturers of DC Drives. Earlier versions of VFD’s would only 
control  typically about 10 cycles. As micro processors became more available 
designs of  VFD’s  began improving until they  became the choice of industry 
over DC Drives.  
It was  while I was attending a training session for VFD’s that I discovered 
that  disconnecting one of the incoming phases the drive would continue to 
operate,  with the loss of phase alarm on. Talking with the instructor, the alarm 
was  disabled and the unit continued operating the motor. 
It  wasn’t long after that I was working on a project that needed a 35 HP 
motor and  only single phase available. Of course the power company would be 
happy to run a  3 phase line (I think they had in mind an open V but charging for 
all three  phases. RotoPhase was not available for something that large so I 
contacted the  instructor (He was also a factory Rep) and told him what I 
needed. He showed up,  we worked it out. We use existing single phase feed from the 
power company. The  existing service was a 120/240 Volt 200 amp service. 
Setting the frequency drive  for soft start we were in business. This installation 
has been in operation for  about 16 years give or take. 
Al  Shumate
 
 
In a message dated 1/16/2009 5:45:26 P.M. Eastern Standard Time,  
yurtle_t@xxxxxxxxx writes:

I've  successfully run a 1/2 hP single phase motor with a single phase to 
three  phase VFD. I simply turned off phase monitoring on the drive, then 
adjusted  the voltage to get 240 volts phase to phase, and fed the motor two phases. 
The  only problem was that if I turned the speed down too much, the motor  
centrifugal switch disengaged. This could have been corrected by grinding away  
some of the centrifugal switch weights, but I upgraded to a 3 phase motor  
instead.

Adam


--- On Fri, 1/16/09, William Noble  <william_b_noble@xxxxxxx> wrote:

> From: William Noble  <william_b_noble@xxxxxxx>
> Subject: RE: [TCML] VFD motor
>  To: "Tesla list" <tesla@xxxxxxxxxx>
> Date: Friday, January 16,  2009, 10:18 AM
> a VFD drives a three phase motor only, you cannot  use
> "any old induction motor".  I am unaware of ANY
> VFD  that will do more than synchronize to the 60 hz, and
> those are  exceedinly rare - if you want a synchronous motor,
> a VFD is absolutely  the wrong way to do it.
>  
> (note, just for the group, that  I have a couple of small (1
> hp if I remember right, see my web,  wbnoble.com) 440V VFDs
> available at an attractive price if you can use  them)
> 
> ----------------------------------------
> >  Date: Fri, 16 Jan 2009 09:23:43 -0500
> > From:  sdbogard@xxxxxxxxx
> > To: tesla@xxxxxxxxxx
> > CC:
>  > Subject: [TCML] VFD motor
> >
> > Quick question  guys,
> > Does a motor to be used with a VFD have to be  modified
> for
> > synchronous operation or can it be any old  induction
> motor. Thanks.
> >
> > Scott  Bogard.
> > _______________________________________________
>  > Tesla mailing list
> > Tesla@xxxxxxxxxxxxxx
> >
>  
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