Re: [CAD_CAM_EDM_DRO] Three phase 50 V. Help wanted

Don wrote:

>My problem is that the torque amplifiers have 50V 3-phase motors
>(50Hz, 1/40 hp, 2750 r.p.m.) which are integral to the units.
>Repowering them with single phase or D.C. motors would be a mission
>and I am attempting to build a 3 phase 50V power supply to run from
>single phase domestic supply (230V, 50Hz, neutral-earthed).
>I have built a "Rotary Converter" prototype from internet search
>info,....which doesn't work....
>

What you really want is a servo amp for AC servo motors (induction
motors rather than
permanent magnet brushless). These definitely exist, and are what many
of the high-end
machine tools are now using. Yaskawa, Rockwell/Allen-Bradley, etc. are
making these
drives now. A rotary converter is not of any use, because it will run
the motors at
constant speed. You need a drive that can move the motors from creep to
full speed.

Oh, but wait! 1/40 Hp? You can't move a cutting machine with a 1/40 Hp
motor. My
underpowered Bridgeport retrofit uses 1/8 Hp DC servo motors, which can
produce 1/2 Hp
peaks for a moment.

I think you should find some stepper motors or good-sized servo motors
to do the job
directly. Using motors to drive amplifiers to drive bigger motors
doesn't make any
sense to me.

search eBay for used servo amps, they do come up pretty regularly.

Jon