The shaft load on a 40-hp, 60-Hz, 460-V, four-pole induction motor is such as to cause the machine to operate at 1447 r/min. The stray load, loss and combined windage and friction loss when operating at this load, are 450 W and 220 W, respectively. The motor parameters in ohms/phase are R1 = 0.1418 Rz = 1.10 XM = 21.27 X1 = 0.7273 X2 = 0.7284 Rfe = 212.73 The motor is NEMA design D and wye connected. Determine (a) motor input impedance per phase; (b) line current, (c) active, reactive, and apparent power and power factor, (d) equiva lent rotor current, (e) stator copper loss, (f) rotor copper loss, (g) core loss: (h) air-gap power, (1) mechanical power developed, () developed torque; (k) shaft horsepower, (1) shaft torque; (m) efficiency. (n) Sketch the power-flow diagram and enter all data. (O) If the speed at rated load is I 190 r/min, determine the expected minimum locked-rotor torque.

The shaft load on a 40-hp, 60-Hz, 460-V, four-pole induction motor is such as to cause the machine to operate at 1447 r/min. The stray load, loss and combined windage and friction loss when operating at this load, are 450 W and 220 W, respectively. The motor parameters in ohms/phase are R1 = 0.1418 Rz = 1.10 XM = 21.27 X1 = 0.7273 X2 = 0.7284 Rfe = 212.73 The motor is NEMA design D and wye connected. Determine (a) motor input impedance per phase; (b) line current, (c) active, reactive, and apparent power and power factor, (d) equiva lent rotor current, (e) stator copper loss, (f) rotor copper loss, (g) core loss: (h) air-gap power, (1) mechanical power developed, () developed torque; (k) shaft horsepower, (1) shaft torque; (m) efficiency. (n) Sketch the power-flow diagram and enter all data. (O) If the speed at rated load is I 190 r/min, determine the expected minimum locked-rotor torque.

Delmar's Standard Textbook Of Electricity

7th Edition

ISBN:9781337900348

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter35: Harmonics 916

Section: Chapter Questions

Problem 3RQ: Would a positive-rotating harmonic or a negative-rotating harmonic be more harmful to an induction...

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