All currents in FEEM are peak, so for RMS the values have to be scaled accordingly.

In order to set up a 3-phase system of currents, with the same value of 1 A peak for each phase, and phase angles as indicated, the following strings should be entered in the appropriate current definition in FEMM magnetic model, with I denoting the imaginary number (I² = -1):

I1 (at 0°) = 1

I2 (at +120°) = -0.5 + I * 0.866

I3 (at -120°) = -0.5 - I * 0.866

In order to use different amplitudes, these can be just multiplied by the required constant. For example, in order to achieve a current of 10 A rms in each phase (with the same angles), the values should be multiplied by 10 * 1.4142 = 14.142 (so that the sqrt(2) scaling is also applied). Hence:

I1 (at 0°) = 14.142

I2 (at +120°) = -7.0711 + I * 12.2474

I3 (at -120°) = -7.0711 - I * 12.2474

Note that you can multiply directly inside the input box, because the value will be evaluated correctly. So for example, typing in:
-0.5 * 14.142 - I * 0.866 * 14.142 will set it to -7.0711 - I * 12.2474.

Setting up the complex value of I2