EE 551 · Chapter 5
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Explain the torque-slip characteristic of a 3-phase induction motor and explain the effect of rotor circuit resistance on the characteristic.
A 400 V, 4-pole, 50 Hz, 3 phase slip ring induction motor has a star connected stator winding and a star connected rotor winding. At standstill the voltage between the two slip rings is 190V. The stator impedance is 0.5 + j2.5 Ω. The rotor resistance and reactance at standstill are 0.06 Ω and 0.3 Ω respectively. The stator to rotor turn ratio is 1: 1. The motor consumes 600 Watts at no load. Calculate: i) Speed at which the motor develops the maximum torque. ii) Efficiency of the motor when it is running at 1,380 rpm.
Why is starter used in three phase induction motors? List different types of starting methods typically used and explain any two of them.