A radial transmission line system can be represented by a generating source connected to a three-phase transformer – (11kV/132kV, 50MVA, 10 % reactance) to which an overhead transmission line (j100 Ω) is connected. Connected to the other end of the transmission line is another three-phase transformer (132kV/33kV,50MVA, 12% reactance). This three-phase transformer located at a 33kV substation supplies a load of 30MW at a power factor of 0.8 lagging. The voltage level of the substation is to be maintained at 30kV.  

Use a base of 100MVA and 33kV .             

Use the above information to answer Q12 – Q16 12. 

Calculate the per unit value of reactance of the sending end transformer. 

a) 0.20                     

b) 0.25                               

c) 0.30                                

d) 0.343            

e) none 

13. Calculate the per unit value of reactance of the receiving end transformer. 

a) 0.32                     

b) 0.24                                

c) 0.41                                

d) 0.51             

e) none 

14. Calculate the per unit value of the reactance of the transmission line . 

a) 0.864          

b) 0.575            

c) 0.768                     

d) 0.683           

e) none 

15. Calculate the  per unit value of the load current . 

a) 0.451        

b) 0.685            

c) 0.418                     

d) 0.214            

e) none 

16 Calculate the per unit value of the receiving end voltage  . 

a) 0.851        

b) 0.910            

c) 0.718                     

d) 0.814            

e) none