Re: VFD tachometer sanity check

Dave:

That's actually what I had in mind. If the frequency, as converted
to 0-10 volts analog is linear to speed, then I can do the math
(including actual motor speed [after slip] of 1750 RPM and pully
ratio to my Bridgeport) and get a net final speed to calibrate to a
voltmeter.

Is it doable easily?

Jeff

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<davemucha@j...> wrote:

> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "washcomp" <jeff@w...>

wrote:

> >
> > I'm thinking of buying a variable frequency drive for my

Bridgeport.

> >
> > The 10 Volts off the analog contacts of the VFD can be set to be
> > proportional to the frequency.
> >
> > If the RPM is linear to the frequency (after slip has been taken
> > into account), and if the voltage is linear to the frequency,

then

> > shouldn't the voltage be linear to the speed?
>
> Certanly....IF voltage and frequency were linear.
>
>
> >
> > If this is the case (the real question I'm asking), once the

setup

> > is calibrated, this should give the ability to have an accurate
> > electronic analog tachometer on the control pendant I'm

designing

> > without resorting to an additional optical encoder.
>
>
> I would considder using the VSD output of 0-5, 0-10 or 4-20mA that

it

> linear to frequency. would make life a lot simplier. The manual
> should offer a lot of details on what outputs are available.
>
> Also, most of the drives I've seen lately have a display that

shows

> whtever you want, frequency, speed, percentage of input.... all

sorts

> of different things.
>
> Dave