290 



SYNCHRONOUS MOTORS. 



to the motor is also considerably increased, since the 

 product E 2 x Ce, is considerably greater in Fig. 137 

 than in Fig. 136. It is thus seen that decreasing the 

 excitation of a lagging machine has the effect of increasing 

 the power supplied by the other to drive it, if the machines 

 remain at the same relative angle. 



If the conditions indicated by Fig. 136 represent an 

 alternator and motor with equal armature voltage, and if 



FIG. 136 DIAGRAM OF CIRCUIT 

 CONNECTING Two ALTERNATORS 

 IN PARALLEL. 



10 20 30 40 50 60 70 80 

 SCALE OF AMPERES 



10 



FIG. 137. FIG. 138. 



DIAGRAMS OF CIRCUIT CONNECTING ALTERNATOR 



AND SYNCHRONOUS MOTOR. 



the excitation of the motor is then diminished to the value 

 E z in Fig. 137, the load on the motor remaining the 

 same as before, the motor will receive an increased 

 amount of power, and will be consequently accelerated 

 The phase angle between the two machines will conse- 

 quently increase, until the power given to the motor 

 becomes the same as originally sufficed to drive it, as 

 shown in Fig. 136. Under these circumstances, the con- 

 ditions will become those indicated in Fig. 138, where the 

 two voltages have become more nearly opposite, and the 

 resultant voltage and cuifent have both decreased in 

 value. The power-factor in the case of both motor and 



