Single Phase motors on 3 Phase

Can anyone help, please!
I know you can run a 3 ph motor on single phase but can you run a
motor supplied a single phase on 3 phase?
I have a milling machine that has been converted to single phase. The
motor for the cross travel has RYB and neutral connections and has a
capacitor connected across RB. Now, my guess is that the mftr makes a
3ph motor as standard and converts to single phase by the use of the
capacitor. I have 3ph so would like to convert back to 3ph. The plate
on the motor does say single phse so it is a manufacturers conversion,
not a home one.
Any comments.
TIA.
Reply to
Dorutland
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If you have a neutral as part of your three phase installation then you will have 240v between any phase and neutral so single phase motors (or anything else) can be run of it.
I don't know of a way to create an artificial neutral with a suitably low impedance to draw any useful power with just capacitors.
Bob
Reply to
Bob Minchin
One pont is that there may be a good reason why the manufacturer did this and without access to an original schematic, it's hard to tell if the motor is actually 3 phase and not some sort of split phase motor.
One reason might be to limit the torque, as you never get full power from a 3 phase motor using a cap to phase shift the third phase. In the absence of a shear pin, it could be a reasonable way to limit torue and thus avoid mech damage at the end stops.
Theat's for the feed motor - the spingle motor would never be converted to 1 ph from 3 using single cap by any sane manufacturer, as you would not get full power and such techniques are considered something of a bodge in electrical engineering circles...
Chris
Reply to
ChrisQuayle

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