I have a German mill (Optimum F30) and the motor label says 400V, 50hz, 3phase, 3A, 1.5KW. Can I safely plug this into a 440V, 60hz power power supply. I realize the RPM will be effected but will it hurt the motor?
If you keep the volt : hertz ratio the same, there is no harm done.
Right. It's the same as if you running the motor on a VFD powered by 50Hz 400V and pushed the speed up to 120%. The VFD would raise its output frequency to 60Hz and its output voltage to 480V.