Q4 (a) Outline the locked rotor and no load tests for an induction motor and indicate the necessary measurements and calculations to determine equivalent circuit parameters. (b) The per phase equivalent circuit parameters for a 3 phase, 4 pole star connected induction machine operating off a 230 V (phase voltage), 50 Hz supply are shown on Table Q4b. Assuming that friction and windage losses are negligible, determine the following for operation at a slip of 0.025: (i) (ii) (iii) (iv) (v) (vi) The per phase equivalent circuit (including values below) The actual motor speed (rpm) The mechanical power (W) The torque (Nm) The motor losses (W) The motor efficiency (%) Parameter Value XM R. 352 1052 R, 0.20 0.152 1.50 R, Х Table Q4b (c) Induction motors can also operate off 2 phase AC supplies. Outline the necessary electrical supply and mechanical winding arrangements for this type of motor.

Q4 (a) Outline the locked rotor and no load tests for an induction motor and indicate the necessary measurements and calculations to determine equivalent circuit parameters. (b) The per phase equivalent circuit parameters for a 3 phase, 4 pole star connected induction machine operating off a 230 V (phase voltage), 50 Hz supply are shown on Table Q4b. Assuming that friction and windage losses are negligible, determine the following for operation at a slip of 0.025: (i) (ii) (iii) (iv) (v) (vi) The per phase equivalent circuit (including values below) The actual motor speed (rpm) The mechanical power (W) The torque (Nm) The motor losses (W) The motor efficiency (%) Parameter Value XM R. 352 1052 R, 0.20 0.152 1.50 R, Х Table Q4b (c) Induction motors can also operate off 2 phase AC supplies. Outline the necessary electrical supply and mechanical winding arrangements for this type of motor.

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 3 phase, 50 Hz. 2 pole alternator is excited to generate the bus ber Example 3.32.5 voltages of 11 kV at no load, Calculate the synchronizing power per degree of mechanical displacement of the rotor. The machine is star connected and the short circuit current for this excitation is 1200 amperes. Neglect armature winding resistance
c) A 3 phase 6 pole star connected induction machine operates from a 120 V (phase voltage) and 50 Hz supply. Given the equivalent circuit parameters shown in Table Q4, and assuming the friction and windage loss is negligible, calculate the following parameters when operating at 1200 rpm: i. The slip (%). ii. The mechanical power (W). iii. The torque (Nm). iv. The efficiency (%). v. The no load current (A). d) Determine the following parameters for the motor in Q4c at start-up (zero speed): i. The motor phase current (A). ii. The power factor. iii. The input supply power (W). Parameter Value XM Units 85 Ω Re 250 250 R Xeg R Ω 200 Table Q4
Due to increased armature m.m.f., the armature reaction during load condition will decrease and hence the field flux will be increased. Select one: True False
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1A Armature of fl A alternator 220V D.C Supply f2 IA, field + 0-220V - 220V winding 12 Report : 1- Draw the open (no-load) characteristics from the above tables. 2- Derive the equation for an induced voltage on the armature. 3- Discuss your results clearly and briefly.