Advanced circuital models of squirrel-cage induction machines account also for higher harmonics of the self and mutual inductances of the stator and rotor windings. They result from both the discrete windings' distribution and the non uniform air-gap due to eccentricities and slotting. The resistance of the rotor-cage bars is modified to account for skin effect during starting up. Assumption of constant resistance for the stator winding results in far slower modulations of the stator current envelope, after switching on the machine on three-phase power supply, than it is normally registered by live measurements [3]. Increasing of the stator resistance (during starting up) evidently accelerates the above mentioned modulations in the simulated currents' envelopes, as well as reduces the time interval during which these modulations do exist. Though the results of simulations included in the contribution justify the magnification of the stator resistance (for simulating purposes) during starting up, there is still lack of physical interpretation for this approach.