276 



ALTERNATING CURRENTS 



sive amount of copper, an induction regulator is often connected 

 to each feeder. This maintains the voltage at the distribution 

 point practically constant. 



The induction regulator is a transformer having a movable 

 secondary. In this way it closely resembles the induction motor. 

 The general principle of the single-phase type is shown in Fig. 



Short-Circuited 

 Tertiary Winding 



FIG. 254 (a). Single-phase induction regulator. 



Secondary 



Load 



Primary 



Fia. 254 (6). Connections of a single-phase induction regulator. 



254. An ordinary winding is placed in the slots on the stator 

 and a drum winding is placed in the rotor slots. When the second- 

 ary is in the plane of the primary, the maximum electromotive 

 force is induced in the secondary, because the mutual inductance 

 of the windings is a maximum when the secondary is in this posi- 

 tion. When the secondary is at right angles to the primary, the 



