TRANSFORMERS 301 



The secondary impedance is 



?2 = T Z + jxz = 0.6 + 0.8 j ohms. 

 The primary exciting admittance is 



yo = go-jbo= (2-6j)10- 6 . 



The current output or secondary current of the transformer is 



1 000 000 



' ' n an = ^.5 and taking this as axis the various quantities 

 ^UUU /\ U.oU 



may be expressed in rectangular coordinates as follows: 

 Secondary current 

 7 2 = 62.5 + Oj. 

 Secondary terminal e.m.f. 



E = 2000 (cosfl +j sin0) = 1600 + 1200 j, where cos B = 0.8 

 is the load power factor. 

 Secondary impedance eoin.f . 

 Ej" = 7 2 f2 = 62.5 (0.6 + 0.8 j) = 37.5 + 50 j. 

 Secondary induced e.m.f. 



E 2 = E + Ej" = 1637.5 + 1250 j. 

 Primary induced e.niofo 



E b = E' = ^E 2 = 10 # 2 = 16,375 + 12,500 j, 



712 



Primary exciting current 



J =E'y = (16,375+ 12,500 j) (2-6j) 10~ 6 = 0.11-0.07;. 

 Primary load current 



Total primary current 



/! = /' + 7 = 6.36 - 0.07 j. 

 Primary impedance e.m.f. 



Ei!" = /ifi = (6.36 - 0.07 j) (50 + 80 j) = 324 + 505 j. 

 Primary impressed e.m.f. 



E! = E' + #/" = 16,699 + 13,005 j. 

 Taking absolute values, 

 primary impressed e.m.f. 



Ei = V (16,699) 2 + (13,005) 2 = 21,160 volts, 



