THE CONTINUOUS CURRENT MOTOR 



185 



doing the same work as before, will be given by the dotted 

 curve of Fig. 112, in which the maximum value is much 

 less than it was before. In fact this motor equipped with 

 the flywheel might be much smaller than the one without 

 the flywheel. The motor through which current A', Fig. 

 112, flows need be only about two-thirds as large as if cur- 

 ent A were the current input. 



Effect of the Flywheel. The action of the motor equipped 

 with a flywheel is as follows: At time ti, Fig. 112, the load 

 on the motor suddenly increases and so causes the motor 

 to begin to slow down. As it slows down, the rotating 



Time 



FKJ. 112. Current Consumption of a Compound Motor, with and 

 without Flywheel. 



flywheel is slowed down also and so gives up some of its 

 kinetic energy. During the time from t\ to fe, Fig. 112, 

 the electrical input to the motor is not as great as the power 

 demanded by the load, hence the motor slows down and 

 the retarding flywheel assists the motor to carry the load. 

 During this slowing down process, the current input to the 

 motor must increase somewhat. 



If at the time t\ the speed is 1000 r.p.m., and at the 

 time t2 the motor has slowed down to 800 r.p.m. and the 

 speed-load curve of the motor is as given in Fig. 113, the 

 current must increase during the same period from OD 

 to OE. In Fig. 112, ah equals OD of Fig. 113 and Uz 



