264 



ELECTRICAL ENGINEERING 



The same result can be obtained by using rectangular co- 

 ordinates. 



If I is taken as real axis, then the terminal e.m.f. E leading it 

 by angle <f> is 



E = E cos < + jE sin 0. 



a 



FIG. 243. 

 The synchronous impedance drop is 



and the no-load e.m.f. is 



E Q = E + E '" = (E cos < + Ir) + j (E sin < + 7z ), 

 or its absolute value is 



E Q = V(E cos + 7r) 2 + (# sin + Ix Q )*. 



By reference to these figures it is seen that for the same terminal 

 e.m.f. E, and the same current 7, a much larger value of E is 

 required for inductive loads than for non-inductive loads and a 

 much smaller value for capacity loads than for non-inductive 

 loads. 



