B4. Fig. B4 shows the per-phase equivalent circuit of a 380 V, 4-pole, 1440 rev/min, 50 Hz, star-connected three-phase i
Posted: Mon May 09, 2022 7:55 am
B4. Fig. B4 shows the per-phase equivalent circuit of a 380 V, 4-pole, 1440 rev/min, 50 Hz, star-connected three-phase induction motor. Rs : Stator Resistance 0.222 R'r: Referred Rotor Resistance 0.2 Ω Xs: Stator Reactance 0.6 32 X'r: Referred Rotor Reactance 0.6 22 Rs Ri's jX' WW jXs 000 7000 Vs Fig. B4 (a) Evaluate (i) the slip at rated speed, (ii) the supply current at rated speed, (iii) the torque at rated speed, (iv) the slip at maximum torque, (v) the supply current at maximum torque, and (vi) the maximum torque. (3 marks) (3 marks) (2 marks) (2 marks) (3 marks) (2 marks) (b) An electrical engineer reported a three phase induction motor (5 marks) performed a low efficiency at low frequency operation with VVVF control. What is the reason behind?