Electric Motor Control
10th Edition
ISBN: 9781133702818
Author: Herman
Publisher: CENGAGE L
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Textbook Question
Chapter 3, Problem 27SQ
Select the best answer for each of the following.
If an operator pushes a start button on a three-phase induction motor and the motor starts to hum, but not run, the probable trouble is
- a. one fuse is blown and the motor is single phasing.
- b. the overload trip needs resetting.
- c. the auxiliary contact is shorted.
- d. one phase is grounded.
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Students have asked these similar questions
3 Phase Induction motor
I want a short answer please
11. The number of three-phase induction motor parts and the function of each part.
12. How to know the terminals of an induction motor if they are not encoded in the terminal box.
13. How can a three-phase induction motor be reversed?
14. Number of tools used to protect devices - transformers and induction motors - in the laboratory.
15. The number of devices required to conduct a test No load. for a three-phase induction motor
16. The number of devices required to conduct a test For a three-phase induction motor, a Blocked rotor
17. What is the use of a test? For a three-phase induction motor? Blocked rotor and No load
18. When conducting the no-load test, the current rises in the first second of preparation when using the direct connection method.
the reasons for that?
19. When performing a non-pregnancy test, we notice a decrease in the ability factor. the
reasons for that? 20. Connect an induction motor directly to the source.…
23. When the circuit breaker is always tripping, most likely
There is an overloading
c. The supply line are open
a.
b.
There is an over current
d. The load is removed
24. The synchronous motor is not inherently self- starting because
the rotating magnetic field does not have enough poles
b. the rotating magnetic field is produced by only 50 HZ frequency currents
the force required to accelerate the rotor is to the synchronous speed in an instant is
d. the starting devices to accelerate the rotor to near synchronous speed is absent
25. Synchronous motor has speed
a. slight drop in speed on full load
b.high speed at low torque
а.
с.
c. constant speed
d. low speed at high -
20.a. A capacitive sensor is used to detect the presence of _______ objects.A. ferrousB. nonmovingC. nonconductiveD. magnetic20.b. A three-phase motor can be made to run backwards byA. connecting a resistor in series with the armature.B. reversing the control voltage connections.C. reversing three of its power leads.D. reversing two of its power leads.
Chapter 3 Solutions
Electric Motor Control
Ch. 3 - Prob. 1SQCh. 3 - How many poles are required on motor starters for...Ch. 3 - If a motor starter is installed according to...Ch. 3 - Using the time limit overload or the dashpot...Ch. 3 - What causes the AC hum or chatter in AC...Ch. 3 - What is the phase relationship between the flux in...Ch. 3 - In what AC and DC devices is the principle of the...Ch. 3 - What does the electrician look for to remedy the...Ch. 3 - What type of protective enclosure is most commonly...Ch. 3 - What advantage is there in using combination...
Ch. 3 - What safety feature does the combination starter...Ch. 3 - Prob. 12SQCh. 3 - How is the size of the overload heaters selected...Ch. 3 - What type of motor starter enclosure (include NEMA...Ch. 3 - Prob. 15SQCh. 3 - Prob. 16SQCh. 3 - Prob. 17SQCh. 3 - Prob. 18SQCh. 3 - Select the best answer for each of the following....Ch. 3 - Prob. 20SQCh. 3 - Prob. 21SQCh. 3 - Select the best answer for each of the following....Ch. 3 - Prob. 23SQCh. 3 - Select the best answer for each of the following....Ch. 3 - Select the best answer for each of the following....Ch. 3 - Select the best answer for each of the following....Ch. 3 - Select the best answer for each of the following....Ch. 3 - Prob. 28SQCh. 3 - Select the best answer for each of the following....Ch. 3 - Prob. 30SQCh. 3 - Prob. 31SQCh. 3 - What is the difference between a grounded control...Ch. 3 - A control transformer has a primary voltage of 480...
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