Electric Motor Control
10th Edition
ISBN: 9781133702818
Author: Herman
Publisher: CENGAGE L
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Chapter 2, Problem 8SQ
To determine
Choose the best option in which low-voltage (or under voltage) protection (LVP) is available.
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Students have asked these similar questions
QUESTION 12
The proper way to determine the required over-current protection is to:
determine the FLA based on the nameplate.
Use the standard rule of thumb that the over-current protection shall be 7 to 10x the locked rotor amps.
determine the watts by converting the HP rating on the nameplate to watts.
to determine the FLC by looking up the value in the appropriate table(s) in the NEC as they relate to the horsepower of the motor.
A starter turns very slowly and has excessive cranking current draw. When removed from the vehicle and bench tested, the starter spins normally and current draw is within specifications. Technician A says poor battery connections may be the cause. Technician B says an internal engine problem may be the cause. Who is correct?
c) 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)
Chapter 2 Solutions
Electric Motor Control
Ch. 2 - If the contacts on a manual starter cannot be...Ch. 2 - If the handle of an installed motor starter is in...Ch. 2 - How may an automatic operation be achieved when a...Ch. 2 - What does the term trip-free mean as it relates to...Ch. 2 - Prob. 5SQCh. 2 - Prob. 6SQCh. 2 - Prob. 7SQCh. 2 - Prob. 8SQCh. 2 - Select the best answer for each of the following....Ch. 2 - Select the best answer for each of the following....
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- A starting resistor will most likely be needed in a/ an A. line starter.B. reduced-voltage starter.C. full-voltage starter. D. across-the-line starter.arrow_forwardWhat safely feature does the conbination starter provide that individual motor starting assemblies do not?arrow_forward3 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.…arrow_forward
- 3.) The time delay fuse using the strict standard rating for 2Ø, 230 V, 7.5 hp SCIM motor is A. 25 A B. 30 A C. 35 A D. Any of the abovearrow_forwardDraw an electrical diagram for a Star Delta starter with a forward rotation and reverse rotation switch.arrow_forward3 Phase Induction motor I want a short answer please 21. Compare the value of the drawn current of a star-connected induction motor first and then delta second. 22. How to identify the induction motor before working on it? 23. What's in the identification plate .name plate 24. List only laboratory methods for starting a three-phase induction motor. 25. In the Star Delta panel to control a three-phase induction motor, what is the function of the timer? 26. What does the reading of the gauges used in the no-load test on three-phase induction motors represent? 27. How is the starting method decided for an induction motor having an identification plate? 28. How does an increase in voltage affect across )Variable (Auto transformer.) on the speed of a three-phase induction motor 29. Use an ohm meter to find the resistance of each phase of an induction motor whose terminals are delta-connected without changing its connection? What is theSkin effect 30. How can the torque-speed characteristics…arrow_forward
- Match list 1 (Motors) with List II (Applications) and select the correct answer using the codes given below List I List II A. Hysteresis motor 1. Signaling devices B. Shaded pole Motor C. Reluctance motor D. Universal Motor 2. Grinders 3. Timing devices 4. Projectorsarrow_forwardQ11/ choose the correct answer In 3-phase induction motor, the starter is necessary because _____________________________.? 1- it runs at dangerously high speed 2- motor takes 5-7 times its full-load current 3- starting torque is very high 4- it may run in reverse directionarrow_forwardA squirrel-cage induction motor has a nameplate full-load current of 78 amperes and a marked temperature rise of 30C. The motor requires a NEMA size 4 starter. Using the overload heater chart in Figure 34-8, what size overload heaters should be used to protect this motor?arrow_forward
- Dual- voltage rated pump motors are rated!?arrow_forwardA forward-reverse motor starter must be prevented from form reversing while running in the forward rotation. What is done? a. install electrical limit switches b. install electrical interlocking c. install a NC stop button d. install a NO pushbutton.arrow_forward3.64 The rotor frequency of a 3-phase, 5 kW, 400 V, 50 Hz, 4-pole slip ring induction motor is 25 Hz. The speed of the motor when connected to a 400 volt, 50 Hz supply will be 10 (a) 1500 rpm (c) 750 rpm (b) 1000 rpm (d) Zeroarrow_forward
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