

DETAILED STUDY OF OPERATION WITH NORMAL LOAD 41 



which one, A\H, is in phase, and the other, OH, is in quadrature, 

 with the current 7. The effect of the motor is therefore equivalent 

 to an apparent reactance, which is here positive, 



OH 



combined with an apparent resistance 



-R. 



Finally, the electric power developed by each of the two E.M.F.'s 

 E\ and E 2 will be 



and 



cos 



P 2 = 2 7cos 



A,C 



(i3) 



and 



where (/-Ei, /) and (^.E 2 , 7) mean the angle of lag between 

 7, and between E 2 and 7, respectively. 



The ohmic loss in the circuit (I 2 R) is equal to the difference 

 P\ P 2 . Let us now transform the diagram, as above, in such 

 manner that A\A 2 shall represent the current, in magnitude and in 

 phase. To obtain the magnitude, 

 it will be sufficient to use, for 

 measuring the amperes, a scale 

 Z times greater than the scale of 

 volts, Z being the numerical 

 value of the impedance, expressed 

 in ohms. 



To obtain the lag of the cur- 

 rent thus represented, with re- 

 spect to the generator E.M.F. 

 EI, it will be sufficient to draw 

 (Fig. 26) a stationary right line 

 A\N making the angle 7- in ad- 

 vance of OA\. It will be seen 

 immediately, on comparing Figs. 

 25 and 26, that the angle NA\A% 

 formed by the vector A\A%, with the line NA^ is equal to the angle 

 OA iC previously referred to, and, consequently, represents the apparent 

 phase-angle ([>. 



for current, / 



FIG. 26. 



