Original poster: "Leigh Copp" <Leigh.Copp@xxxxxxxxxxx>
Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>
At 03:22 PM 9/29/2006, you wrote:
>Original poster: "Leigh Copp" <Leigh.Copp@xxxxxxxxxxx>
>
>Hi Jim,
>
>
>Depending on your budget, a 3 phase variable speed drive
(there is a 50
>HP unit on e-bay right now for $330 for example) would not
only allow
>you to control start up, but it would create true 3 phase
from single
>phase. Most of the drives out there use a static rectifier
(diode, not
>SCR or transistor) and will run on single phase provided that you
>de-rate them accordingly (50% is typical).
They'll run a motor (and relatively smooth running too), but the
filter capacitance usually isn't enough to hold the dc bus voltage up
between half cycles.
<LC>Very true, but as long as you de-rate the drive by/to
50% the DC link filter components are large enough. I have 8 of
these things from 2 HP to 50 HP running in my own shop; most of
them being over 5 HP. I live several kM away from 3 phase, so I
step up the 240V single phase to 575 VAC single phase, and power
the drives from that. My lathe is 25 HP spindle + roughly 5 HP of
hydraulics, feed motors and coolant pump, and it runs from a single
50 HP Allen Bradley Powerflex 700VC. Allen Bradley actually stands
behind the product as long as it is de-rated by 50%, and you follow
their connection requirements (internal cooling fans are power off
of a particular pair of line input terminals, so it matters which
phase you leave unconnected).