Electric Motor Control
10th Edition
ISBN: 9781133702818
Author: Herman
Publisher: CENGAGE L
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Chapter 39, Problem 15SQ
A synchronous motor can be used to increase the power factor of an electrical system by
- a. reducing the speed.
- b. overexciting the stator field.
- c. operating at unity power factor.
- d. applying DC to the stator field.
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8- An induction motor with 580 r.p.m. speed at 60 Hz will have
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a) the motor will run in reverse direction
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a) Shunt motor
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Which of the following statements about three-phase induction motor is false
(A) The speed of rotation of the magnetic field is called the synchronous speed.
(B) A three-phase supply connected to the rator produces a rotation magnetic field.
(C)The rotating magnetic field has a constant speed and constant magnitude.
(D) It is essentially a constant speed type machine.
1.5 A 10‐pole, 380 ‐V, 50 Hz, D‐connected three‐phase induction motor is rotating a quarry belt conveyor. The machine has the following parameters, referred to the stator, on a per phase basis:
Stator Parameters
Winding Resistance................0.19 Ω .........
Winding Reactance.................1.12 Ω..........
Rotor Parameters
Winding Resistance......................0.29 Ω
Winding Reactance.....................1.12 Ω
Magnetising Reactance................................16.8 Ω
Equivalent Core‐loss Resistance....................900 Ω.
The friction and windage losses are 320 W. When the motor runs at its rated slip of 2.6 %. Determine:
1.5.1 The stator current.
1.5.2 Estimate the Output torque of the motor under the rated conditions.
1.5.3 The Motor…
Chapter 39 Solutions
Electric Motor Control
Ch. 39 - Prob. 1SQCh. 39 - What is the effect of the starting winding of the...Ch. 39 - What are typical applications of synchronous...Ch. 39 - Prob. 4SQCh. 39 - A loaded synchronous motor cannot operate...Ch. 39 - Why must a discharge resistor be connected in the...Ch. 39 - Depending on their power factor ratings, what is...Ch. 39 - At what power factor do incandescent lights...Ch. 39 - Prob. 9SQCh. 39 - The speed of a synchronous motor is fixed by the...
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- A DC generator has terminal voltage of 250 V and an induced voltage of 262 V when the generator is loaded. The brush drop is 1 volt per brush and the armature resistance is 0.03 ohm and the shunt field circuit resistance is 35 ohms. Neglected armature reaction and determine the following: (1) The load current. (2) The power of the load in kW. (3) The % voltage regulation.arrow_forwardK-1)The speed of a 3-phase wound-rotor induction motor can be changed by varying the amount of resistance in the rotor circuit. a) true b) false K-2). Which of the following statements are true about a 3-phase synchronous motor? a) It is a constant speed motor even under varying loads. b) It runs at the same speed the magnetic field rotates on the stator. c) It can correct its own, and the supply line's power factor d) all of the above K-3. A) What determines the speed of a 3-phase synchronous motor? a) the number of poles b) the frequency of the supply c) both "a" and "b" d) neither "a" nor "b" K-3)B) From a technician's standpoint, which of the following is the most practical method of providing a wide range of speed control for a 3-phase synchronous motor? a) by changing the frequency b) by changing the number of poles c) both "a" and "b" d) neither "a" nor "b"arrow_forward2. A 2-pole, 50 Hz induction motor supplies 15 kW to a load at a speed of 2950 rpm. a. What is the motor's slip? b. What is the induced torque in the motor in N-m under these conditions? c. What will be the operating speed of the motor be if its torque is doubled? d. How much power will be supplied by the motor when the torque is doubled?arrow_forward
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Working of Synchronous Motor; Author: Lesics;https://www.youtube.com/watch?v=Vk2jDXxZIhs;License: Standard Youtube License