Can you run 220v 50 hertz with standard us 208 three phase
Shooting from the hip I'd say 208 V is too low for most European equipment, which these days expects 230 V +/- 10%, i.e. an actual voltage between 207 and 253 V. As far as I know the US mains voltage is defined as 120 V +/- 5%, so the limits of a 120/208 V supply phase to phase would be 198-218 (rounded to the nearest full V), so in the lower range of a US supply European equipment might complain. Older 220 V +/- 10% equipment should be fine, provided it can cope with the 60 Hz. Induction motors require a higher voltage to run at a higher frequency (e.g. 400 V/50 Hz and 480 V/60 Hz for the same motor).
What actually happens will probably depend completely on the load. Resistive loads have lower power output, switching-mode power supplies might not care at all and work perfectly fine, motors might be damaged.
