A10 Kw, 400 V, 3- Phase induction motor has full load efficiency of 0.87 and power factor 0.85. At standstill at rated voltage the motor draws 5 times full load current and develops a starting torque of 1.5 times full load torque. An autotransformer is installed to reduce the starting current to give full load torque at the time of starting. Calculate the full load current.

Question A 3-phase, 415 V, 4-pole, 50 Hz induction motor draws 5 times the rated current at rated voltage at starting. It is required to bring down the starting current from the supply to 2 times of the rated current using a 3-phase autotransformer. If the magnetizing impedance of the induction motor and no-load current of the autotransformer is neglected, then the transformation ratio of the autotransformer is given by

A 30 kW, 460 V, 1180 rpm, 3 -phase, 60 Hz, Y-connected induction motor has a full-load efficiency of 93.6% and a power factor of 0.83 lagging. The resistance of the stator winding per phase is 0.14 N/phase. Determine: (a) The full-load active power drawn by the motor (b) The full-load line current (c) The full-load rotor winding losses (d) The rotational losses

1. The rotor resistance and reactance per phase of a three-phase wound rotor induction motor are 0.035 and 0.15 ohm respectively. If an additional resistance is added, the starting torque is one half of maximum torque and the full load torque is three-fourth of the maximum. Determine the following: a. Full load speed b. speed at maximum torque c. value of additional resistance per required to achieve these conditions.