Re: why not just change the motor?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Paul <no.spam27@n...> wrote:
>
> Given the choice of using a VFD or trying to find a flange mounted
single
> phase motor with an extended shaft, I know which one I would choose.
>
> Pros & cons of a single phase motor:
> IF one could be found to fit the hypothetical Bridgeport... The
contactors
> would need to be replaced. There would be a high startup current
that may
> trip the mains breaker (so that would need to be uprated).
> I would only get one fixed speed (1480 RPM approx).
> Reduces the resale value of the machine.
>
> Pros & cons of a VFD:
> Needs a dual voltage motor.
> Established and reliable technology.
> Soft start, so no high startup currents.
> DC injection braking.
> Full overload protection for the motor.
> Simple low voltage controls for on/off
> Variable speed from 0 to 2X (depending on the motor).
> Simple forward/reverse control.
> Reasonably priced units available.
> No need to replace contactors as these are bypassed.
> Does not affect the resale value of the machine.
>
> A VFD is both simple and cheap, and far from being a kludge/bodge.
Three
> phase motors and VFD packages are regularly being sold fitted as
standard to
> a number of machine tools by OEM manufacturers.
>
> Regards, Paul.
>
>
> On Friday 23 January 2004 3:41 pm, jlsmith269 wrote:
> > Or, heck, let's get to the heart of the issue, if *I* bought a 2
hp
> > boss 8 cnc, 3ph, I would NOT bother with a vfd on it.. i would get
the
> > wiring and motor from a 2 hp 220 1ph , and bolt it on... and yeah,
I
> > would spend DOUBLE or more for that simple solution, rather than
> > kludge it, knowing I am introducing unknowns into a pc-cnc/enc
setup.
>
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