the resistance of contactor K shall be appreciably lower than the armature winding resistance. the resistance connected in series with the voltage source shall have its value so chosen that closing the contactor does not affect the source current value appreciably (the current value shall not change by more than a few per cent ).the test is performed with the rotor placed along the direct and then the quadrature axis after preliminary magnetization of the machine magnetic system by passing a d.c current through the armature (primary) winding, that will produce saturation . following this , gradual demagnetization is carried out down to the test current value ,and short-circuited or disconnected after closing contactor K.