TAILED STUDY OF OPERATION WITH NORMAL LOAD 81 



Suppose a long-distance power-transmission project in which it 

 jssible to connect, with the distributing system, either some induc- 

 motors working with a certain lag, or else an equipment composed 



>ne-half induction motors and one-half synchronous motors. 

 7he line-current, with the induction motors alone, and with a phase- 



Iw 



le d), would be equal to :. With half the capacity in synchro- 

 cos 



nous motors added, and effecting complete compensation, the current 

 would be equal to I w . 



It should be noted immediately that the loss by resistance-heating 

 in the motors will be exactly the same in the two cases, because the 

 magnetizing current of the synchronous motors has the same value 

 as the reactive current of the induction-motors, it being, however, a 

 current leading in phase. 



Under these conditions, in order to maintain the loss of energy 

 constant in the line, for different values of cos <f>, the cost of line- 

 copper, when the induction-motors alone are used, should be 





A 



P2 



COS(/>' 



and, with complete compensation by means of synchronous motors 

 which carry half the load, the price of line-copper would be 



For equal losses the cost of line-copper is proportional to the square 

 of the current; the saving effected in the cost of copper, by introducing 

 synchronous motors, would therefore be 



E\I 



cos (f> cos (f> I w 2 ' 



co 



or p 2 EiI w { - -j cos 



\COS (/> 



The cost of generators, without compensation, would be 



cos 



