The current depends on the load, your supply has a max of 10 amps, the more the load the higher the current, the voltage phase to phase should be constant at 415v, or 240v from a phase to neutral.
If you were to run a 3 phase device such as a motor or transformer then yes the current would be distributed across all phases, if the device is single phase then the current will just be on one phase and the neutral.
To work out power on a 3 phase system assuming the current is equal on all the phases and the power factor is one you go, volts x current x (square root of 3).