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A 440 V, 50 Hz, 25 hp, 4-pole, Y-connected three-phase wound-rotor induction motor has the following circuit parameters: R1 = 0.46 02, R2 = 0.33 0, x1 = 1.102, X2=0.46 02, and Xm = 25 02. (stator referred) Rotational losses (including core loss) = 500 W (constant). (1) At a slip of 0.04, use the complete equivalent circuit model to calculate: (a) Motor speed (b) Stator current (c) Airgap and shaft torque (d) Input power factor (e) Efficiency (f) Starting current and torque. (2) Use the simplified Thevenen's equivalent circuit to calculate: (a) The developed maximum torque (b) The speed at which the maximum torque is developed. (c) The starting current (d) The starting torque (3) If an external resistance equal to the rotor resistance is added to the rotor circuit, then calculate: (a) The starting current and torque (use the complete equivalent circuit). (b) The developed maximum torque (c) The speed at which the maximum torque is developed. (4) If the supply frequency is reduced to 50 % while the supply voltage is kept at rated value, repeat (1) and (2) above at a slip of 0.04. Compare results. (5) If the terminal voltage and supply frequency are simultaneously reduced to 50 %, repeat (1) and (2) above at a slip of 0.04. Compare results.

A 440 V, 50 Hz, 25 hp, 4-pole, Y-connected three-phase wound-rotor induction motor has the following circuit parameters: R1 = 0.46 02, R2 = 0.33 0, x1 = 1.102, X2=0.46 02, and Xm = 25 02. (stator referred) Rotational losses (including core loss) = 500 W (constant). (1) At a slip of 0.04, use the complete equivalent circuit model to calculate: (a) Motor speed (b) Stator current (c) Airgap and shaft torque (d) Input power factor (e) Efficiency (f) Starting current and torque. (2) Use the simplified Thevenen's equivalent circuit to calculate: (a) The developed maximum torque (b) The speed at which the maximum torque is developed. (c) The starting current (d) The starting torque (3) If an external resistance equal to the rotor resistance is added to the rotor circuit, then calculate: (a) The starting current and torque (use the complete equivalent circuit). (b) The developed maximum torque (c) The speed at which the maximum torque is developed. (4) If the supply frequency is reduced to 50 % while the supply voltage is kept at rated value, repeat (1) and (2) above at a slip of 0.04. Compare results. (5) If the terminal voltage and supply frequency are simultaneously reduced to 50 %, repeat (1) and (2) above at a slip of 0.04. Compare results.

Delmar's Standard Textbook Of Electricity
Delmar's Standard Textbook Of Electricity
7th Edition
ISBN:9781337900348
Author:Stephen L. Herman
Publisher:Stephen L. Herman
Chapter33: Single-phase Motors
Section: Chapter Questions
Problem 17RQ
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please solve question 5 and thanks alot sir 

A 440 V, 50 Hz, 25 hp, 4-pole, Y-connected three-phase wound-rotor induction motor has the following circuit parameters: R1 = 0.46 02, R2 = 0.33 0, x1 = 1.102, X2=0.46 02, and Xm = 25 02. (stator referred) Rotational losses (including core loss) = 500 W (constant). (1) At a slip of 0.04, use the complete equivalent circuit model to calculate: (a) Motor speed (b) Stator current (c) Airgap and shaft torque (d) Input power factor (e) Efficiency (f) Starting current and torque. (2) Use the simplified Thevenen's equivalent circuit to calculate: (a) The developed maximum torque (b) The speed at which the maximum torque is developed. (c) The starting current (d) The starting torque (3) If an external resistance equal to the rotor resistance is added to the rotor circuit, then calculate: (a) The starting current and torque (use the complete equivalent circuit). (b) The developed maximum torque (c) The speed at which the maximum torque is developed. (4) If the supply frequency is reduced to 50 % while the supply voltage is kept at rated value, repeat (1) and (2) above at a slip of 0.04. Compare results. (5) If the terminal voltage and supply frequency are simultaneously reduced to 50 %, repeat (1) and (2) above at a slip of 0.04. Compare results.
Transcribed Image Text:A 440 V, 50 Hz, 25 hp, 4-pole, Y-connected three-phase wound-rotor induction motor has the following circuit parameters: R1 = 0.46 02, R2 = 0.33 0, x1 = 1.102, X2=0.46 02, and Xm = 25 02. (stator referred) Rotational losses (including core loss) = 500 W (constant). (1) At a slip of 0.04, use the complete equivalent circuit model to calculate: (a) Motor speed (b) Stator current (c) Airgap and shaft torque (d) Input power factor (e) Efficiency (f) Starting current and torque. (2) Use the simplified Thevenen's equivalent circuit to calculate: (a) The developed maximum torque (b) The speed at which the maximum torque is developed. (c) The starting current (d) The starting torque (3) If an external resistance equal to the rotor resistance is added to the rotor circuit, then calculate: (a) The starting current and torque (use the complete equivalent circuit). (b) The developed maximum torque (c) The speed at which the maximum torque is developed. (4) If the supply frequency is reduced to 50 % while the supply voltage is kept at rated value, repeat (1) and (2) above at a slip of 0.04. Compare results. (5) If the terminal voltage and supply frequency are simultaneously reduced to 50 %, repeat (1) and (2) above at a slip of 0.04. Compare results.
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