Re: VFD tachometer sanity check

--- 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