CH. V SEKIES-WOUND MOTOES 121 



motor is switched into the circuit it cannot move unless 

 the torque produced by the current is greater than the 

 load on the motor. If the induction factor can be increased 

 by shunting some of the current through the magnets, any 

 required acceleration can be obtained by adjusting the 

 amount of current thus shunted. The motor will then 

 speed up, and in doing so will diminish the current by 

 its induced tension. If the generator is provided with a 

 constant current regulator, this will not happen, and the 

 current will be unaltered, the increased tension required 

 to make up the terminal tension on the recently started 

 motor being provided by the generator. 



If the induction factor remained unaltered, and the load 

 were constant, the motor would go on speeding up without 

 limit. If, however, the motor is provided with a governor, 

 the induction factor may be automatically reduced when 

 any desired speed has been attained. If the governor is 

 set for a certain speed, it will adjust the induction factor, 

 say by shunting the magnets, so that if the speed is too 

 high, the induction factor will be reduced, and the torque 

 assisting the motion be made less than that due to the 

 load ; the motor will then be retarded. Similarly if the 

 speed is too low, the induction factor may be increased. 



If the load is reduced, the assisting torque due to the 

 current will cause the motor to accelerate unless the 

 governor reduces the induction factor. If the load is in- 

 creased the governor will increase the induction factor, 

 keeping the speed constant. If the load should increase 

 beyond the ability of the governor to hold the speed, the 

 motor will simply be retarded until it stops, without in 

 any way affecting the other motors in the circuit. The 

 motor may be set to run at any convenient speed : theoreti- 



