This paper analyzes the numerical identifiability of the electrical parameters of induction machines. Formulations of the single-and double-cage induction machine, with and without core-losses in both models, are developed. It is shown the impossibility to identify all the parameters of these models when only external measurements (voltage, current, speed, and torque) are used. One proposed solution is the formulation of machine equations by using the minimum number of parameters (which are identifiable parameters). As an application example, the parameters of a double-cage induction machine are identified using steady-state measurements corresponding to different angular speeds.