APPLICATIONS OF CIRCLE DIAGRAM 



203 



BP, produced with US fixes the slip scale, the length US representing 

 a slip of 100 per cent. The slip corresponding to any other value of 

 the current is, on the same scale, equal to the distance from R of the 

 point of intersection of the line drawn from B to the extremity of the 

 current vector. 



118. Applications of Circle Diagram 



Having constructed our diagram, we may use it to find the relation 

 connecting any two out of the various quantities which we have to 

 consider current, power factor, slip, torque, mechanical power, and 

 electrical efficiency. These relations are conveniently represented in 



* ^ \ 



y *s 



<>/ // 



POWER. AUSOK.DED BY MOTOR. 



FIG. 132. Curves derived from Circle Diagram. 



the usual way by curves, and a very large number of different modes 

 of representation may be adopted. Two of the most commonly 

 employed are those in which the electrical power supplied to the 

 motor, and the mechanical power developed by it, are taken as 

 abscissae, the remaining quantities being plotted as ordinates. An 



