In this paper, a method to determine load conditions under which the armature current of a salient pole synchronous machine is on the q-axis is described. The proposed method allows the determination of a locus in the $P-Q$ space in which the armature current is completely on the q-axis. The derivation of these conditions simplifies the determination of the machine q-axis parameters during load rejection tests, since it eliminates the necessity for trial and error procedures or power angle estimation. The method was tested in a 100 MVA, 13.8 kV, 60 Hz, 40 poles salient pole synchronous machine installed in a hydro power plant. Tests results show that loads calculated with the proposed method are in fact points where the armature current is on the q-axis.