Current for a 3ph compressor?

Formula for current in a 3 phase motor:

I = P/(E x Eff. x PF x 1.732)

I = Current

P = Power, 45kW in your case

E = Voltage, you didn't say

Eff. = Motor nameplate Efficiency, assume 80% (.80) if you don't know

PF = Power Factor at Full Load, assume 70% (.70) if you don't know

1.732 = Sq. Rt of 3, because it is a 3 phase motor (I'm assuming, because 45kW is typically too big to run on single phase).

So assuming you have not yet received your compressor and are attempting to determine in advance what size service you will need for it (which moves us beyond the earlier sarcasm), assuming you have a 400V motor and service;

I = 45kW / (400 x .8 x .7 x 1.732)

I = 45000 / 387.97

I = 116A FLC

What your compressor actually draws will likely be less than this, but you must base your design criteria for service equipment on this in advance to be safe.