a. A three-phase, 220-V, 60-Hz induction motor runs at 1,140 rev/min. Determine the number of poles (for minimum slip), the slip, and the frequency of the rotor currents.
b. To reduce the starting current, a three-phase squirrel-cage induction motor is started by reducing the line voltage to Vs/2. By what factor are the starting torque and the starting current reduced?