SYNCHRONOUS MACHINES. 



[Exp. 



working conditions, E' drops back or advances until the mechan- 

 ical power developed, namely E' X Of, just equals the power 

 demanded. The motor does this automatically, if it possibly can ; 

 otherwise it stops. 



The operation is stable so long as any dropping back of the 

 armature gives increased mechanical power. Beyond a certain 

 maximum power, point 5 in Fig. 2, a further dropping back 



1 



FIG. 2. Synchronous motor diagram ; the solid part of each circle is the 



operating range. 



of the armature means a decrease in power. Loaded beyond its 

 maximum, the motor will stop. Even if not overloaded, unstable 

 operation could not be maintained, for, assuming the power de- 

 veloped to be just equal to the demand, any momentary retarda- 



