If you want to supply your motor by using power source which has different frequency than it is written at the nameplate of your motor, you need to take care about value of magnetic induction in ferromagnetic core of your motor, because of possibility of appearing of unallowed warming of ferromagnetic core which can contribute to damaging of ferromagnetic core of your motor. This fact is a consequence of entering magnetising curve into area of saturation in H-B characteristic which describes behavior of magnetic induction in depends of intensity of magnetic field. In the area of saturation, as long as you would like to increase voltage, magnetic induction will stay at the same value which is the equal with value of magnetic induction under nominal voltage. So, by increasing voltage you will have only unallowed warming of ferromagnetic core, so you need to take care about ratio of voltage and frequency:

U1/f1=U2/f2=const.

This means that if you have motor designed for 240V and 50Hz and you want to connect it into power supply with 60Hz, your maximum allowed voltage will be:

240/50=U2/60 => U2=60*240/50=288V which is higher than 240V

So, as you can see after calculation, you can supply your motor with 240V and 60Hz.