The reactance per phase as compared to resistance per phase of an inductor motor is
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Answer:
You are asking about the impedance specifically of the rotor, not the stator. Ok.
First, resistance of the rotor circuit is entirely set by the sizes and lengths of the conductors in the circuit, and by the conductance of the materials used to form the conductors and the temperature at which they are operating. Other than for a wound rotor motor, the resistance value of the rotor circuit doesn’t change regardless of what is happening to the motor.
The inductive reactance of the rotor depends on how many magnetic field lines the conductors are cutting, which is a function of the “slip rate” of the rotor. The stator sets up a rotating magnetic field which rotates synchronously with the line frequency, rate depending on frequency and the number of pole pairs wound into the stator for each phase. For example with 60 hz supply and 2 pole pairs per phase, the magnetic field rotates at 60 / 2 x 60 = 1800 RPM. When the rotor rotates at 1725 RPM, the slip rate is 75 RPM. This 75 RPM of slip causes stator magnetic lines to cut the bars of the rotor circuit, inducing current in the rotor bars which circulates according to the location of the stator field, and induces magnetic poles into the rotor steel. The collapsing of the rotor’s magnetic field induces inductive reactance into the rotor circuit which obviously has to be taken into account in designing the motor, but it appears from online articles, to be not a very significant factor in that. The resistance of the rotor cage is far more of a design factor, seriously affecting the motor’s starting and running characteristics in every way.