A 480 kW, 50 Hz, 3.3 kV, eight-pole-ped wound-rotor induction motor has the following parameters referred to the stator: Stator winding resistance: Rotor winding resistance: 0.65 0.50 Ω Stator leakage inductance: 10 mH Rotor leakage inductance: Magnetizing inductance: 10 mH 1040 mH Calculate the synchronous speed of the motor. (1) (ii) If the motor runs with a full-load slip of 0.03, calculate the full-load rotor speed. (iii) With the help of the equivalent circuit calculate the full-load stator current and its power factor. (iv) What is the full-load developed torque of this motor? Calculate the efficiency of the motor on full-load if the core losses and the friction and windage losses are equal to 25 kW. Pu THEN 245 (vi) It is desired to start the motor with maximum torque using external resistors connected in series with the rotor winding. Calculate the resistance required to achieve maximum starting torque, and calculate the value of the resulting torque. (vii) By what factor does the addition of the external resistors increase the starting torque? ! e e exte d

A 480 kW, 50 Hz, 3.3 kV, eight-pole-ped wound-rotor induction motor has the following parameters referred to the stator: Stator winding resistance: Rotor winding resistance: 0.65 0.50 Ω Stator leakage inductance: 10 mH Rotor leakage inductance: Magnetizing inductance: 10 mH 1040 mH Calculate the synchronous speed of the motor. (1) (ii) If the motor runs with a full-load slip of 0.03, calculate the full-load rotor speed. (iii) With the help of the equivalent circuit calculate the full-load stator current and its power factor. (iv) What is the full-load developed torque of this motor? Calculate the efficiency of the motor on full-load if the core losses and the friction and windage losses are equal to 25 kW. Pu THEN 245 (vi) It is desired to start the motor with maximum torque using external resistors connected in series with the rotor winding. Calculate the resistance required to achieve maximum starting torque, and calculate the value of the resulting torque. (vii) By what factor does the addition of the external resistors increase the starting torque? ! e e exte d

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

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A three phase, 4 pole, 3300 V, 50 Hz, star connected Induction motor, has identical primary and referred secondary impedance of value 3+j9 Ohm per phase. Using the approximate circuit, calculate: A. The full load torque at rated slip of 5%. B. The maximum torque at normal voltage and frequency.
A 3-phase, 50-Hz, 415V, Y-connected, 4-pole, squirrel-cage rotor induction motor, has a per-phase of rotor winding impedance of 0.015+j0.08Ω. Assuming that the stator winding impedance is negligible, determine the following; i) The maximum slip, smax ii) The maximum pull-out torque, τmax iii) The required starting torque, τstart iv) The external resistance that should be added in series with rotor resistance if ratio between starting torque and the maximum torque should be 0.85
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The parameters of a three-phase, 50 Hz, 6-pole, 400 V star connected induction motor are r1 = 0.3 ohm, x1 = 0.5 ohm, r’2 = 0.15 ohm and x’2 = 0.2 ohm. The voltage and frequency of the induction motor is controlled by a power electronic converter (inverter). Calculate the required inverter output frequency and voltage to drive the induction motor load at 0.2 the rated speed of the motor and calculate the current drawn by the motor for that case. The formula for the maximum slip is given below:
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