25 August 2016

ELECTRICAL QUESTIONS AND ANSWERS-MCQ-9-ETO


QUESTIONS AND ANSWERS FOR ETO

1. A shading coil used in an AC magnetic controller, functions to _____________.        
A. reduce vibration and noise in the contactor          
B. prevent flux buildup in the operating coil               
C. eliminate arcing when the contacts close              
D. energize the operating coil and "pull in" the contacts       
Ans: A

2. In a cartridge-type fuse, the metal element is contained in a ___________________.            
A. porcelain window         
B. thermal cut out             
C. fiber tube        
D. flasher device
Ans: C

3. In process control terminology values which can change  without distinct increments, such as temperature, pressure, or level are called ____________.      
A. binary values  
B. digital values  
C. bumpless values            
D. analog values
Ans: D

 4. The proper way to apply plastic electrical tape to an  electric cable splice is to _____________.
A. apply tape to the braided cover, but avoid touching it
B. wind the tape so that each turn overlaps the turn before it             
C. apply the tape in one non-overlapping layer only
D. heat the tape with a soldering iron for good bonding
Ans : B

5. Which of the following statements is true concerning all three-phase alternators?
A. Each has three separate but identical armature windings acted on by one system of rotating magnets.            
B. Each has one armature winding acted on by three identical but separate systems of rotating magnets.
C. All three-phase alternators are designed to operate with a 0.8 leading power factor.
D. The three phases always provide power to the load through three sets of slip rings and brushes.
Ans: A

6. A low-voltage protection circuit is used in electric motor starting equipment to _____________.
A. trip circuit contactors when the motor over speeds due to low voltage        
B. trip circuit contactors when the motor develops a short circuit due to low voltage   
C. allow the motor to restart automatically on restoration of voltage without manually resetting
D. prevent the motor from restarting automatically on   restoration of voltage             
Ans: D

7. Time delayed or delayed action-type fuses are designed to _____________.
A. prevent grounds in branch circuits           
B. prevent opens in motor circuits
C. permits momentary overloads without melting   
D. guard lighting and electronic circuits      
Ans: C

8. Silicon diodes designed for a specific reverse breakdown voltage, become useful as an electronic power supply voltage regulator, called _____________.
A. tunnel diodes 
B. hot-carrier diodes         
C. compensating diodes   
D. Zener diodes  
Ans: D

9. Which of the following statements best describes the material known as varnished cambric?
A. Felted asbestos sealed with varnish.       
B. Cotton cloth coated with insulating varnish.         
C. Rubber insulation coated with a layer of tin.
D. Paper impregnated with mineral oil, specially wrapped with nonmetallic tape, and coated with varnish.
Ans: B

10. A synchronous motor maintains synchronism with the rotating field because _____________.          
A. field strength varies directly with rotor slip           
B. DC current applied to the rotor coils causes the rotor magnets to lock in with the rotating flux of the stator    
C. the stator poles are dragged around due to the flux created by the excitation current            
D. the stator flux rotates in the opposite direction  
Ans: B

11. What is the maximum allowable primary current of a 2 KVA step-down transformer with a four to one turns ratio if connected across a 440 volt line?      
A. 1.1 amps         
B. 4.5 amps         
C. 18.1 amps       
D. 27.7 amps      
Ans: B

12. The part of a fuse that melts and opens the circuit is made of _____________.      
A. copper and antimony  
B. steel and Babbitt          
C. aluminum or beryllium alloy       
D. zinc or an alloy of tin and lead  
Ans: D

13. The cross-sectional area of shipboard electrical cable is expressed in _____________.         
A. millimeters     
B. gage numbers               
C. centimeters    
D. circular mils   
Ans: D

14. To effectively clean a commutator in good physical   condition, you should use ____________.          
A. Trichloride ethylene     
B. kerosene         
C. a canvas wiper
D. a commutator stone   
Ans: C

15. What will be the phase angle relationship of a six-pole, three-phase, rotating field generator?          
A. 60°    
B. 120° 
C. 180°  
D. 360° 
Ans: B

16. The function of amortisseur, or damper windings in a  synchronous motor is to _____________.       
A. eliminate slippage        
B. provide excitation        
C. provide starting torque               
D. increase efficiency       
Ans: C

17. The main difference between a motor control circuit   containing low voltage protection and low voltage release is that the latter contains _____________.               
A. a magnetic operating coil          
B. normally open line contacts       
C. thermal-overload protection     
D. a momentary-contact start button         
Ans: D

18. Fuses placed in series with a thermal trip-type circuit  breaker are used for _____________.             
A. time-delay protection 
B. short-circuit protection
C. short duration surge protection
D. sustained overload protection  
Ans: B

19. On an engine throttle control system, the auxiliary control circuits are provided with devices to prevent excessive over travel of the pilot valve by the synchronous motor.  These devices are called _________________.         
A. overlap sensors
B. limit switches 
C. over travel relays          
D. proximity switches       
Ans: B

20. When charging lead-acid batteries, you should reduce the charging rate as the battery nears its full charge capacity to ______________.             
A. prevent excessive gassing and overheating           
B. allow equalization of cell voltages           
C. reduce lead sulfate deposits      
D. increase lead peroxide formation            
Ans: A

21. Ammeters and voltmeters used in sinusoidal AC power systems indicate which of the following values of the waveforms measured?          
A. Peak value      
B. Root-mean-square value            
C. Average value
D. Maximum value
Ans: B

22. Before reassembling any machinery, you should _____________.               
A. replace all bearings regardless of length of service             
B. apply a heavy coat of oil to all mating surfaces    
C. clean any corroded surfaces and file all burrs smooth         
D. coat all parts with alemite grease           
Ans: C

23. The purpose of the commutator and brushes on a DC generator is to _____________.        
A. transfer generated direct current voltage from the armature to the line    
B. convert the alternating voltage generated within the  armature to a direct voltage               
C. provide a sliding contact method to excite the field            
D. reduce sparking between the armature and the carbon brushes   
Ans: B

24. The most common source of excitation for synchronous motors is a/an _____________.
A. low voltage battery     
B. motor attenuator set  
C. DC exciter generator   
D. AC supply        
Ans: C

25. The type of feature afforded auxiliaries vital to the operation of propelling equipment, where automatic restart after a voltage failure would not create a hazard, is termed _____________.            
A. low voltage protection
B. high amperage protection         
C. low voltage release      
D. high amperage release               

Ans: C

"Take up one idea. Make that one idea your life--think of it, dream of it, live on that idea. Let the brain, muscles, nerves, every part of your body, be full of that idea, and just leave every other idea alone. This is the way to success." --Swami Vivekananda

SHARE

DON'T MISS

ELECTRICAL QUESTIONS AND ANSWERS-MCQ-9-ETO
4/ 5
Oleh

Subscribe via email

Get Free Study Materials? Add your email address to subscribe.