236 ELECTRICAL ENGINEERING 



The effective value of the currents in the three phases is the same 



and is 7 = - 7^- 



V2 



<f> is the angle of lag of the current in each phase behind the e.m.f . 

 generated in that phase. 

 The current in line A is 



IA = ii ^2 = 7 sin (B 0) 7 sin (6 < 120) 



= V3 7 sin (e - <f> + 30), .... (237) 

 and its effective value is 



7 A = V3^=V37. 



-T 



FIG. 204. 



The current in line B is 

 IB = iz - i* = IQ sin (0 - 4> - 120) - 7 sin ^ - - 240) 



= \/3 7 sin (6 - - 90), (238) 



and its effective value is 



IB = V3 7. 

 The current in line C is 



ic = is ii = Io sin (6 $ 240) 7 sin (0 0) 



= V3 7 sin (0 - <j> - 210), .... (239) 

 and its effective value is 



I c = \/37. 

 Thus the currents in the three lines are equal in magnitude and 



