DIAGRAM FOR COUPLED SYNCHRONOUS MOTORS 167 



phase-angle, AN, lagging by the angle, y, with respect to U, and 

 point off, at N, the center of the circles of constant internal 

 power, which will be the same for the generator as for the motor. 

 The three points A\AAz are then joined by a straight line, A\Az, 

 which represents twice the product Z<7, of the impedance Z* by 

 the current, 7, that is to say twice the impedance e.m.f. of the 

 circuit. In reality the e.m.f. U may be considered as being that of 

 a " line " absorbing the energy of the generator and supplying the 



Perpend* cu 



$ : ~ f lP l 



1" \ ^ 



i-4u^: " 



^ 



,f 

 d i 



X 



FIG. 84. 



same energy to the motor. We thus introduce a " fictitious " line 

 which does not change the phenomena in any way, but which has 

 the advantage of enabling the diagram to be generalized completely. 



AA\ 



The current / passing between the two alternators is equal to ^~ 



^i 



and it lags behind A A \ by the angle y. 



In the " two-reactions " theory, this diagram is modified in 

 the manner now to be explained. The phases of the currents are 



