21 August 2016

ELECTRICAL QUESTIONS AND ANSWERS-MCQ-7-ETO



QUESTIONS AND ANSWERS FOR ETO

1. The greatest detrimental effect on idle electrical   equipment, such as cargo pump motors, is the _____________.    
A. loss of residual magnetism        
B. absorption of moisture in the insulation
C. insulation varnish flaking            
D. dirt collecting on the windings 
Ans B

2. The frequency output of an operating alternator is   controlled by the _____________.         
A. relative speed of the rotor poles              
B. number of turns of wire in the armature coil        
C. strength of the magnets used  
D. output voltage              
Ans. A

3. Which of the following physical characteristics does a  wound-rotor induction motor possess that a squirrel cage motor does not?               
A. Slip rings         
B. End rings         
C. A centrifugal switch     
D. End plates      
Ans. A 
  
4. The current at which a magnetic-type overload relay tends to trip may be decreased by raising the plunger further into the magnetic circuit of the relay. This action ___________.        
A. reduces magnetic pull on the plunger and requires more  current to trip the relay  
B. reduces magnetic pull on the plunger and requires less  current to trip the relay     
C. increases magnetic pull on the plunger and requires more current to trip the relay
D. increases magnetic pull on the plunger and requires less current to trip the relay   
Ans. D 
  
5. Protection against sustained overloads occurring in   molded-case circuit breakers is provided by a/an __________.   
A. overvoltage release     
B. thermal acting trip       
C. thermal overload relay               
D. current overload relay
Ans. B
   
6. Which of the listed logic gates is considered to be a BASIC building block (basic logic gate) used in logic diagrams?      
A. NAND              
B. OR    
C. NOR 
D. All of the above.           
Ans. B  
 
7. When choosing a battery for a particular application, major consideration should be given to the battery's ____________.      
A. amp-hour capacity       
B. terminal polarity           
C. stability under charge 
D. ambient temperature rise         
Ans. A

8. The rated temperature rise of an electric motor is the  _____________.    
A. average temperature at any given latitude          
B. normal temperature rise above the standard ambient   temperature at rated load
C. average temperature rise due to resistance at 10% overload        
D. permissible difference in the ambient temperature of the motor due to existing weather conditions
Ans. B
   
9. Which of the following represents the accepted method of cleaning dust and foreign particles from electrical   equipment while limiting damage to electric components?  
A. Carefully wiping off the components with a soft cotton rag.           
B. Blowing a high velocity stream of compressed air rapidly across the components.  
C. Using a vacuum cleaner to remove debris from the components. 
D. Using carbon tetrachloride as a cleaning solvent to clean the components.              
Ans. C

10. Regarding an AC generator connected to the main electrical bus; as the electric load and power factor vary, a   corresponding change is reflected in the generator armature reaction. These changes in armature reaction are   compensated for by the _________          
A. governor speed droop setting  
B. voltage regulator         
C. balance coil    
D. phase-balance relay    
Ans. B

11. In an induction motor, rotor currents are circulated in therotor by _____________.            
A. slip rings and brushes 
B. an armature and brushes          
C. inductive reaction of the rotating stator field      
D. external variable resistors        
Ans. C
   
12. An electrical device which prevents an action from occurring until all other required conditions are met is called a/an ___________.    
A. limit  
B. monitor           
C. modulator      
D. interlock         
Ans. D 
  
13. A circuit breaker and a fuse have a basic similarity in that they both _____________.         
A. can be reset to energize the circuit        
B. should open the circuit when overloaded              
C. will burn out when an over current flow develops               
D. all of the above             
Ans. B

14. The electrolyte in a lead-acid storage battery consists of distilled water and _____________.
A. hydrogen chloride        
B. calcium chloride            
C. sulfuric acid    
D. muriatic acid 
Ans. C

15. The torque produced by a motor when its shaft will not turn, even though rated voltage is applied to the stator, is known as _____________.               
A. locked-rotor torque     
B. pullout torque               
C. breakdown torque       
D. torque margin               
Ans. A 
  
16. Electrical leads and insulation on a motor should be painted with ____________. 
A. heat-resisting acrylic   
B. heat-resisting aluminum            
C. insulating varnish         
D. insulating white lead   
Ans. C
17. Voltage generated by most AC generators is fed from the  machine to the bus by means of ____________.
A. brushes on a commutator         
B. brushes on slip rings    
C. slip rings on a commutator        
D. direct connections from the stator         
Ans. D

18. A degree of control over the speed of a slip ring inductionmotor can be obtained by _____________.
A. adjusting governor linkage        
B. changing the number of phases to the motor      
C. inserting resistance into the stator circuit            
D. inserting resistance into the rotor circuit             
Ans. D
   
19. A circuit breaker differs from a fuse in that a circuit  breaker _____________.       
A. melts and must be replaced      
B. is enclosed in a tube of insulating material with metal  ferrules at each end              
C. gives no visual indication of having opened the circuit       
D. trips to break the circuit and may be reset           
Ans. D

20. Heat sinks are frequently used with _____________.     
A. power transistors        
B. vacuum tubes
C. tunnel rectifier diodes 
D. all of the above
Ans. A

21. Incandescent lamps are classified according to __________.       
A. shape of bulb and type of service             
B. size and style of base  
C. operating voltage and wattage
D. all of the above             
Ans. D 
  
22. The alarm system for an engine order telegraph uses small selsyn motors attached to the indicators. The alarm soundswhen the rotors are _____________.           
A. in synchronous position, no current is flowing, and the  relays are open      
B. in synchronous position, no current is flowing, and the  relays are closed   
C. not synchronized, current is flowing, and the relays are open
D. not synchronized, current is flowing, and the relays are closed     
Ans. D

23. As a general rule, the first troubleshooting action to be taken in checking faulty electric control devices is to  _____________.               
A. draw a one line diagram of the circuitry
B. test all fuses and measure the line voltage          
C. take megger readings 
D. insulate the apparatus from ground       
Ans. B

24. An electrical device which employs a stationary armature and a rotating electromagnetic field is used aboard ship as a ____________.  
A. magnetic amplifier       
B. ship's service alternator
C. three-wire DC generator           
D. saturable core reactor               
Ans. B 
  
25. The main purpose of the auxiliary winding on a split-phase,single-phase motor is to _____________.
A. limit the starting voltage           
B. increase the starting current    
C. start the motor             
D. keep the motor running in the event the main winding should fail 
Ans. C

26. Which of the following statements describes the significance of ambient temperature in relation to the service life of electronic components?     
A. Ambient temperature should be as high as possible to drive off moisture. 
B. Increased ambient temperature decreases the service life of electronic components.           
C. Ambient temperature is not significant as long as the  relative humidity is kept low.              
D. A reduced ambient temperature causes a corresponding reduced service life.         

Ans. B    

"If you genuinely want something, don't wait for it--teach yourself to be impatient." --Gurbaksh Chahal

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ELECTRICAL QUESTIONS AND ANSWERS-MCQ-7-ETO
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