A 111 kW, 320 V, 50 Hz, 6 poles, 974 rpm, Y-connected squirrel cage induction motor has following parameters referred to the stator: R, = 0.06 N, R, = 0.06 N, X, X, = 0.1 N. Motor speed is controlled by constant control. When driving an conveyor belt load the torque equation of the conveyor belt is given by TL = 770 N.m. 1- If the frequency is 50 Hz, calculate: • The motor speed N = RPM • The starting current AZ 2- If the frequency is decreased to 10 Hz, calculate: • The motor speed N = RPM • The starting current AZ 3- If the frequency is increased to 60 Hz, calculate: • The motor speed N = RPM • The starting current I1 = AZ

A 111 kW, 320 V, 50 Hz, 6 poles, 974 rpm, Y-connected squirrel cage induction motor has following parameters referred to the stator: R, = 0.06 N, R, = 0.06 N, X, X, = 0.1 N. Motor speed is controlled by constant control. When driving an conveyor belt load the torque equation of the conveyor belt is given by TL = 770 N.m. 1- If the frequency is 50 Hz, calculate: • The motor speed N = RPM • The starting current AZ 2- If the frequency is decreased to 10 Hz, calculate: • The motor speed N = RPM • The starting current AZ 3- If the frequency is increased to 60 Hz, calculate: • The motor speed N = RPM • The starting current I1 = AZ

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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1a
4. An induction motor is represented as a line diagram and an equivalent circuit. Find: The number of poles. a. b. The synchronous speed of the stator field C. The slip 480V, 3-0, 50HZ 60 KW 1476 rpm w 0.10 10.40 www /0.4 ( ww 0.10 (12
) Discuss the relationship between the starting torque and supply voltage of rotating transformer with necessary equations ) A 6-pole, 3-phase induction motor operates from a supply whose frequency is 50HZ. Calculate: a) The speed at which the magnetic field of the stator is rotating. b) The speed of the rotor when the slip is 0.05. c) The frequency of the rotor current when the slip is 0.04.
Q22/ A three phase induction motor with supply frequency of 50 Hz , 10 poles. If the slip is 4 % at a certain load, determine (a) the synchronous speed, (b) the speed of the rotor (c) the frequency of the induced e.m.f in the rotor and speed of the induction motor if the slip changes to 5.75 %
A 420 Vdc, 8 pole Compound DC motor runs at 729 rev/min when drawing a load of 60 A from the supply when meeting a load demand of 28 kW. The compound motor has a Lap connected armature with 816 conductors. The Armature, Interpole, Series, and Shunt resistances are 0.295 Q, 0.0155 Q, 0.00118 Q, and 147 Q respectively. The series field has 6 turns per pole while the shunt field has 2800 turns per pole. Under full load conditions, the shunt current is 3.75 A, and the Friction and windage loss is Pf/w = 0.782 kW. Consider c =6 for lap winding. Assume constant shunt current and friction and windage loss, determine for a reduced output load of 14.5 kW; (a) The new armature current; (b) The new speed of the motor
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A 4 pole,lap wound,dc. generators has 42 coils with 8 turns per coils. if is driven at 1120 rpm, if useful flux per pole is 21 mWb,calculate the generated e. m. f. Find the speed at which it is to be driven to generate same emf. as calculated above,with wave wound armature.
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g) What is an advantage if the starting Torque of the induction motor is higher than the nominal load Torque? h) What are the main differences when the equivalent circuits of transformer and asynchronous motor are examined?
A four-pole, three-phase induction motor drives a turbine load. At a certain operatingpoint the machine has 4 percent slip and 87 percent efficiency. The motor drives aturbine with torque–speed characteristic given by TL = 20 + 0.006ω2,where TL is theload torque at the shaft. Determine:(1) the torque at the motor-turbine shaft.(2) the total power delivered to the turbine.(3) the total power consumed by the motor.
h has rotor e.m.f. Speed of the induction motor and the frequency of its [970 r.p.m.; 1.5 Hz] 4. A 3-phase, 50-Hz induction motor with its rotor star-connected gives 500 V (r.m.s.) at standstill between the slip-rings on open-circuit. Calculate the current and power factor at standstill when the rotor winding is joined to a star-connected external circuit, each phase of which has a resistance of 10 2 and an inductance of 0.04 H. The resistance per phase of the rotor winding is 0.2 2 and its inductance is 0.04 H. Also, calculate the current and power factor when the slip-rings are short-circuited and the motor is running with a slip of 5 per cent. Assume the flux to remain constant. [10.67 A; 0.376; 21.95 A; 0.303] 5. Obtain an expression for the condition of maximum torque of an induction motor. Sketch the torque- slip curves for several values of rotor circuit resistance and indicate the condition for maximum torque to be obtained at starting. If the motor has a rotor resistance of…
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