Re: Looking for mini-VFD for 120VAC/1ph

--- In CAD_CAM_EDM_DRO@yahoogroups.com, JanRwl@... wrote:

>
>
> In a message dated 8/4/2006 10:17:37 P.M. Central Daylight Time,
> indigo_red@... writes:
>
> so neither can get proper triggering off of the AC zero
> crossings.
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> A VFD doesn't WORK that way!
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> [Non-text portions of this message have been removed]
>

The comment was about two conventional phase controls (on on the
router and another external) not working. The post while mentioning
a VFD was about speed control of the trim router. All the VFD's I
have seen are to control 3 phase AC motors. Since the speed of most
AC motors is contolled by the number of stators and poles and very
little by the base frequency a VFD is not practical for single phase
motors and for a universal motor only the voltage reduction will
vary the speed. Lower voltage also means lower torque so at speeds
below 50% you start to get motor stalls under load,