Calculating slip, LSB, and USB for induction motor
Slip speed is synchronous speed minus operating speed. Rated slip speed is synchronous speed minus rated motor speed. Rated motor speed should be marked on the motor rating plate. Per-unit slip is calculated similarly based on synchronous speed. The motor design parameters required to calculate rated slip speed are normally available only to the motor designer. From approximately zero slip and no load to rated slip at rated load, operating slip is approximately linearly proportional to operating torque.

In motor current spectrum analysis or signature analysis, side bands of the fundamental and harmonic frequencies of the motor current can be used to detect defects in the rotor bars and other problems. There may be "normal" harmonic frequencies and amplitudes associated with the rotor bar skew and the number of rotor bars compared to the number of motor poles and stator slots. The information required to calculate the "normal" data would normally be available only to the motor designer. There are research papers and other information about signature analysis techniques that suggest how measured data can be analyzed.