THE SYNCHRONOUS MOTOR 



315 



81. Speed-load Curves. The speed of a synchronous 

 motor is absolutely constant throughout its range of 

 operation. If an excessive overload is put on the motor, 

 it will pull out of synchronism with the line and a very 



FIG. 203. A Synchronous Machine with Exciter on same Shaft. 



heavy current will rush through the armature. This 

 causes the circuit breakers to open and the motor is cut 

 off from the supply line and stops. It must then be re-started 

 and synchronized as described in a previous paragraph. 

 That overload at .which the motor falls out of synchronism 



