SYNCHRONOUS MOTORS. 



271 



The experiment should therefore be repeated first with 

 gradually decreased excitation for each operation of switching 

 on to the circuit, and then with increased excitation, until 

 the lower and upper limits for which the motor can be started 

 are reached. The variation in the armature-starting current 

 produced by under and over excitation should be noticed. 



The results of the experiment should then be tabulated 

 in the following manner. 



EXPERIMENT IN STARTING SYNCHRONOUS MOTOR. 



Synchronous motor No Type 



Output h.p. at ... .volts and . . . .periods per second. 



Voltage of supply .... 



The next experiment shows more fully the effect of 

 varying the excitation upon the behaviour of a synchronous 

 motor a matter of the greatest importance for the satis- 

 factory working of motors of this type. 



EXPERIMENT XLII. DETERMINATION OF THE EFFECT 

 OF VARIATION OF THE EXCITATION OF A SYNCHRONOUS 

 MOTOR. 



DIAGRAM OF CONNECTIONS. 



FIG. 128. 



