In a power system with negligible resistance, the fault current at a point is 8.00 p.u. The series reactance to be included at the fault point to limit the short-circuit current to 5.00 p.u. is    

1.  3.000 p.u                      

2.  0.200 p.u                 

3.  0.125 p.u                   

4.  0.075 p.u

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4
Correct Answer :

3.000 p.u                      


Explanation :
No Explanation available for this question

Zero sequence currents can flow from a line into a transformer bank if the windings are in    

1.  Ground star/delta                  

2.  delta/star             

3.  star/grounded star                   

4.  delta/delta

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4
Correct Answer :

Ground star/delta                  


Explanation :
No Explanation available for this question

When a line to ground fault occurs, the current in the phase is 100 A. The zero sequence current in this case will be

1.  Zero                 

2.  33.3 A               

3.   66.6 A             

4.  100 A

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4
Correct Answer :

33.3 A               


Explanation :
No Explanation available for this question

Capacitance Voltage Transformer (CVT) is used to    

1.  Improve the power factor of the transmission

2.  Reduce losses in a transmission line

3.  Connect instruments on the LT side

4.  Reduce the incidence of overvoltage surges on transmission lines

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4
Correct Answer :

Improve the power factor of the transmission


Explanation :
No Explanation available for this question

What is the positive sequence currents in a three phase system, when the original phasors at which are Ia = (12 + j 6), Ib = (12 – j 12), Ic = (-15 + j 10)    

1.  14.8 Amp                    

2.  16.2 Amp                  

3.  18 Amp            

4.  10.2 Amp

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4
Correct Answer :

14.8 Amp                    


Explanation :
No Explanation available for this question

The line currents in ampere in phases a, b and c respectively are (400 + j 100), (75 – j 600) and (-300 + j500) referred to the same reference vector. The negative sequence components of currents will be  

1.  25 Amp                  

2.   100 Amp                

3.  160 Amp              

4.  149.9 Amp 

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4
Correct Answer :

149.9 Amp 


Explanation :
No Explanation available for this question

What is the percentage increases of busbar voltage required to compensate for the reactance drop, when the feeder having a reactance of 5% carries a full load current at a p.f 0.8 lagging    

1.  5 %                

2.  1.2 %             

3.  1.8 %                         

4.  3 %

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4
Correct Answer :

3 \%


Explanation :
No Explanation available for this question

A small generating station has a busbar divided into three sections each section is connected to a tie bar with reactor each rated at 5 mVA, 0.1 p.u. reactance. A generator of 8 mVA, rating and 0.15 p.u. reactance is connected to each section of the busbar. The short circuit capacity of the breaker, if a 3- fault takes place on one of the sections of the busbar, will be    

1.  78.73 mVA                   

2.  10.23 mVA              

3.  90.8 mVA                   

4.  85.6 mVA

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4
Correct Answer :

78.73 mVA                   


Explanation :
No Explanation available for this question

A transformer is rated at 11 kV/0.4 kV, 500 kVa, 5% reactance. What is the short circuit MVA of the transformer when connected to an infinite bus    

1.  20 MVA                  

2.  10 MVA                 

3.  15 MVA                       

4.  5 MVA 

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4
Correct Answer :

10 MVA                 


Explanation :
No Explanation available for this question

The following sequence currents were recorded in a power system under a fault condition: I positive = j1.653 p.u. I negative = -j0.5 p.u I zero = -j1.153 p.u The fault is    

1.  Line – ground             

2.  3- phase                   

3.  line - line ground                  

4.  line – line 

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4
Correct Answer :

line - line ground                  


Explanation :
No Explanation available for this question
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