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4. A certain four-pole 240-V-rms 50-Hz delta-connected three-phase induction motor operates at slip 5% at full...

4. A certain four-pole 240-V-rms 50-Hz delta-connected three-phase induction motor operates at slip 5% at full load and has rotational losses (windage + friction) of 100 W. The stator resistance per phase is 0.2 Ohm. The results of no-load and locked-rotor tests on this motor are as follows: No-load test Locked-rotor test Line-to-line input voltage: 240 V 45 V Input active power: 1100 W 1300 W Input line current: 10 A 30 A Using the tests data, determine parameters of the per-phase equivalent circuit. (20 marks) Plot the per-phase equivalent circuit diagram with all parameters indicated. (5 marks)


Using the obtained equivalent circuit, determine the following parameters of the motor: a) Speed at full load (3 marks) b) Frequency of the stator currents at full load (3 marks) c) Frequency of the rotor currents at full load (4 marks) d) Power factor at full load (15 marks) e) Output mechanical power at full load (15 marks) f) Output torque at full load (5 marks) g) Power efficiency at full load (10 marks) h) Starting current (line) (10 marks) i) Starting torque (10 marks)

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