The equivalent-circuit parameters in ohms per phase referred to the stator for a two-phase, 1.0 kW, 220-V,

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The equivalent-circuit parameters in ohms per phase referred to the stator for a two-phase, 1.0 kW, 220-V, four-pole, 60-Hz, squirrel-cage induction motor are given below. The no-load rotational loss is 65 W. R1 = 0.78 R2 = 4.2 X1 = X2 = 5.3 Xm = 93

a. The voltage applied to phase c~ is 220 < 0° V and that applied to phase β is 220 < 65° V. Find the net air-gap torque at a slip s = 0.035.

b. What is the starting torque with the applied voltages of part (a)?

c. The applied voltages are readjusted so that Vα = 220 < 65° V and Vα = 220 < 90° V. Full load on the machine occurs at s = 0.048. At what slip does maximum internal torque occur? What is the value of the maximum torque?

d. While the motor is running as in part (c), phase β is open-circuited. What is the power output of the machine at a slip s = 0.04?

e. What voltage appears across the open phase-β terminals under the conditions of part (d)?

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Electric Machinery

ISBN: 978-0071230100

6th Edition

Authors: Charles Kingsley, Jr, Stephen D. Umans

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