THE INDUCTION MOTOR. 



162. A very beautiful and simple diagram can be drawn, showing 

 in polar co-ordinates the locus of the primary current for a lag, non- 

 inductive load, and a lead in the secondary, as for the same trans- 

 former or motor K L is a constant if O K is constant. Neglecting 

 the primary resistance, a diagram can be constructed for constant 

 terminal voltage by erecting arcs over K L as chord. Arcs flatter 

 than the semi-circle correspond to an inductance in the secondary, 

 the semi-circle corresponds to a non-inductive load, and an arc whose 

 inscribed angle is smaller than a right angle, standing on K L as 

 chord, determines the locus of the primary current for a condenser 

 in the secondary. As the secondary terminal voltage is determined 

 by the circle Oi, in the most simple and beautiful manner the phe- 

 nomena of resonance and kindred phenomena may at a glance be 

 qualitatively and quantitatively understood. But I must leave the 

 construction to the reader, who will find no difficulty in building up 

 the diagram synthetically with the help of Figs. 46, 47, and 48. It is 

 worthy of notice how injurious an inductance in the secondary is 

 with regard to the maximum energy the transformer or motor is 

 capable of taking in, and how much a condenser in the armature 

 of the motor would increase the power of the motor to do work. 



