THE INDUCTION MOTOR. 



The slip is equal to the ratio of the loss in the armature divided 

 by the total energy developed in the secondary, hence equal to the 

 ratio of the ordinates between RCi and RCi, divided by the ordinates 

 between the circle and RC\. 



Mr. Heyland has shown that the diagram may be used to represent 

 the action of the motor when running at a speed above synchronism, 

 i. e., at a negative slip. The -motor then gives energy back upon the 

 line, requiring mechanical energy to drive it. The simplification that 

 I have just introduced, by which the ohmic losses can be taken into 

 account by merely drawing two straight lines, enables us to plot at 

 once the current, d, the torque D, the output P , the power factor 

 cos <j>, and the slip 5", in rectangular co-ordinates as functions of the 

 electrical energy consumed by the motor, and as functions of the 

 electrical energy given back by the generator. 



Fig. 56 illustrates these curves, the plotting of which takes but a 

 few minutes. 



102 



