The correct formulas were already mentioned, if you want to do it right you must consider power factor and the efficiency, allways
remember that when you read the kW in the motor plate, you are reading the output power.
In small motors the powerfactor and the efficiency are small, usually about 0,7 and 0,6.
Usually when the power factor and efficiency are unknow, people use 0,8 and 0,7 and some people forget about efficency ( very bad idea
for small motors ) and they do :
Pmec in kW
I = Pmec *10^3 / (1,73*400*0,8) = Pmec * 1/ (692 * 0,8 ) = Pmec * 1,8