i want to know the wire size to use to connect a machine 100m away to a 3 phase 415v.load capacity is 315Amps?

Answer 1

You don't say how the cable is being installed. So here goes
.6/1kV, 3ph, 3c+E 150mm2 cable installed.
V.Drop/A/100m = 0.029, so you are going to have 9V drop at full load. Generally 5% VD is acceptable so you should only have just ove 2%, so 150mm2 cable would be OK if buried direct.
a) in ground direct buried ------- 330A
b) in 1 way duct ----- 225A
c) in air ------------ 285A

Source: Engineering Standard WMC Corporation Olympic Dam South Australia
Good luck

Answer 2

it needs a power cable that must be specified to the manufacturer before buyin