48 SYNCHRONOUS MOTORS 



The maximum theoretical power is 



I /2OOO\^ 



P= I- -) =62,500 watts. 



l6\ 2 / 



The radii of the power-circles are given by eq. (21); whence we 

 have 



= 62^0\l l6 ::; 



1 J 11 T/-\t> 7 



IO U 



in which P 2 is expressed in watts, p being measured by the scale of 

 volts. In this manner we find the radii for the circles 



of 5 10 20 30 40 and 50 k.w. 



to be 6000, 5700, 5130, 4520, 3750, and 2800 volts: 



These simple calculations give all the elements necessary for the 

 diagram in Fig. 28. In this case the current-circle corresponding to 



tooo 



Amperes 



FIG. 28. 



the normal current of 18.5 amperes has also been drawn, in addition, 

 to show the limit of loads. Let A 2 be any position whatever of the 

 load-point, within this circle ; it is only necessary to measure the various 

 lines, according to the proper scales, to see that the corresponding 

 voltage EZ is 3000 volts, the current strength is n amperes, the 

 reactive current (leading) is 10.5 amperes, and the power is 5 k.w. The 



