In this work we discuss the efficiency of various stator current signatures for monitoring shaft misalignment that could affect mechanical systems when driven by an induction machine speed-controlled. In that respect, we have considered the Motor Current Signature Analysis, the Current Space Vector, and the Current Park Loci, under no-load as well as under full load conditions. On the other hand, the effect of the machine's input-frequency on the detection efficiency is also discussed. Thus, we have assessed these three techniques when the motor is operating under full speed's condition and under half speed's condition. The presented results are experimentally validated on a laboratory's test-rig simulating an angular shaft misalignment.