A 100/5 A bar primary current transformer supplies an O/C relay set at 25% pick up and it has a burden at 5 VA. The secondary voltage is    

1.  1 volt                       

2.  1.25 volts               

3.   2.5 volts                

4.  4 volts

View Answer  
4
Correct Answer :

4 volts


Explanation :
No Explanation available for this question

A transformer rated for 500 kVA. 11 kv/0.4 kV has an impedance at 10% and is connected to an infinite bus. The fault level of the transformer is

1.  500 kVA                         

2.  5000 kVA                   

3.  500 √3 kVA                

4.  none of these

View Answer  
4
Correct Answer :

5000 kVA                   


Explanation :
No Explanation available for this question

If a 100 V/10 V, 50 VA transformer is converted to 100/110 V auto transformer, then rating of the auto transformer is      

1.  550 VA                   

2.   500 VA               

3.  110 VA               

4.  100 VA

View Answer  
4
Correct Answer :

550 VA                   


Explanation :
No Explanation available for this question

Where voltage are high and current to be interrupted is low, the breaker preffered is    

1.  Air blast C.B             

2.  oil C.B               

3.  vaccum C.B               

4.  any of these

View Answer  
4
Correct Answer :

vaccum C.B               


Explanation :
No Explanation available for this question

If time of operation of a relay for unity TMS is 10 secs, then time of operation for 0.5 TMS will be    

1.  20 secs                      

2.  5 secs                    

3.  10 secs                        

4.  none of these

View Answer  
4
Correct Answer :

5 secs                    


Explanation :
No Explanation available for this question

If fault current is 2000 amps, the relay setting 50%  and C. T. ratio is 400/5, then plug setting multiplier will be    

1.  25 amps                   

2.  15 amps                 

3.  50 amps                     

4.  none of these

View Answer  
4
Correct Answer :

none of these


Explanation :
No Explanation available for this question

A long distance overhead transmission line of 220 kV rating is to be protected against faults between phase and ground. The fault resistance including that of the ground is found to vary over a wide range. Which of the following types and relays will give the best performance under the situation indicated above    

1.  Overcurrent relay

2.  Differential relay with percentage relay

3.  Reactance type distance relay  

4.  Impedance type distance relay 

View Answer  
4
Correct Answer :

Reactance type distance relay

 


Explanation :
No Explanation available for this question

Plug setting of a relay can be altered by varying

1.  Number of ampere-turns

2.  Air gap of magnetic path

3.  Adjustable back up stop

4.  None of these

View Answer  
4
Correct Answer :

Number of ampere-turns


Explanation :
No Explanation available for this question

If p.u impedance value of an alternator corresponding to base values 13.2 kV and 30 MVA is 0.2 p.u then p.u value for the base value 13.8 kV and 50 MVA will be

1.  0.306 p.u                 

2.    0.33 p.u            

3.     0.318 p.u                 

4.     0.328 p.u

View Answer  
4
Correct Answer :

0.306 p.u                 



Explanation :
No Explanation available for this question

A lighting arrester connected the line and earth in a power system

1.  Protects terminal equipment against travelling surges  

2.  Protects transmission line against direct lightning stroke  

3.  Suppresses high frequency oscillations in the line

4.  Reflects back travelling wave approaching it

View Answer  
4
Correct Answer :

Protects terminal equipment against travelling surges

 


Explanation :
No Explanation available for this question
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