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 -
Answer all or else skip the question please
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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- 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.arrow_forwarde) How is the direction of the rotating field changed in the three-phase induction motor? f) Write down the operating modes of induction motors depending on the slip values. g) When the speed of the induction motor is zero (or not rotating), in which electrical machine does it match? h) Why are the steel thin layers used in the core of the induction motor? Please answer all. Just two to three lines of answer for each question is enougharrow_forwardc) Based on Figure 3 (c), a basic DOL starter induction motor at a power station is experiencing run-time error and unable to start, based on your understanding, interpret the sequence of troubleshooting shall be carried out to identify the root cause of the abnormalities. 3P 1P MCB MCB STOP K1 START MOTOR Figure 3 (c)arrow_forward
- Q3/ Chose the correct answer for the following 1. Synchronous motors are generally not self-starting because (a) the direction of rotation is not fixed (b) the direction of instantaneous torque reverses after half cycle (c) startes cannot be used on these machines (d) starting winding is not provided on the machines 2. The power developed by a synchronous motor will be maximum when the load angle is (a) Zero (b) 45° (c) 90° (d) 120° 3. An over-excited synchronous motor takes (a) leading current (b) lagging current (c) both (a) and (b) (d) none of the above 4. In a synchronous motor, the magnitude of stator back e.m.f. £& depends on (a) d.c. excitation only (b) speed of the motor (c) load on the motor (d) both the speed and rotor flux 5. A pony motor is basically a (a) small induction motor (c) D.C. shunt motor (b) D.C. series motor (d) double winding A.C./D.C. motorarrow_forwardQuestion 4 Three phase, 50 Hz, four pole Induction motor runs at 1,388 rpm. Calculate the frequency of rotor emf. Write answer correct to two decimal places. DO NOT WRITE UNITarrow_forwardInduction motorarrow_forward
- In Single phase motor starter is used for overload Protection. a. Wire b. MCB c. Relay d. Contactorarrow_forwardMultiple choices cont.: c. The 3M load contacts are welded shut. d. The normally open 3M contact between wire numbers 23 and 31 is hung closed.arrow_forwardQ2: b- Explain how does the three- phase induction motor work? *arrow_forward
- Please solution to this assignmentarrow_forward1. It is a machine that converts mechanical energy to electrical energy. 2. It is a machine that converts electrical energy to mechanical energy. 3. It is cylindrical or drum-shaped where the coils are placed and can either be lap wounded or wave wounded. 4. It connects the commutator to the other parts of the DC machine. 5. It serves as the housing of the dc machine. 6. True or False: The shunt field winding is part of the armature. 7. True or False: The long shunt compound generator is when the armature is in series with the series field winding and parallel to the shunt field winding. 8-10. Your newly built house needs an elevator. Which from the following will be best to use- series, shunt or compound motor and why?arrow_forwardIndustrial Motor Controls 8.a. A typical motor speed control circuit that is controlled by an analog current loop will have a current ofA. 4-20 mA.B. 2-20 mA.C. 5-50 mA.D. 0-10 mA.8.b. Which one of the following statements is true of a disabled contact or coil?A. The disabled element has been automatically disabled due to module failure.B. The disabled element is held false by the PLC.C. A disabled contact or coil is caused by a faulty memory location in the PLC.D. A contact must be in the disabled state before it can be forced ON or OFF.arrow_forward
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