CHAPTER XVI 



154. Compensated induction motor 155. Equivalent of compensated motor 

 156. Effect of varying number of rotor conductors. Speed control 157. Effect 

 of brush displacement 158. Case of synchronous speed 159. Latour alter- 

 nator 160. Heyland alt 



Itcrntitor. 



154. Compensated Induction Motor 



WHILE the induction motor possesses many advantages among 

 which the extreme simplicity of its construction (especially when a 

 squirrel-cage rotor is used) and the small amount of attention (due 

 to the absence of a commutator) which it requires are the most 

 important it also suffers from a somewhat serious disadvantage 

 a comparatively low power factor at light loads (cf. 67). Not only 

 does a low power factor increase the losses in the generators, supply 

 mains, and motor itself, but it renders the voltage regulation of the 

 system much more difficult. By adopting for the rotor an ordinary 

 continuous-current armature having a commutator, Heyland and 

 Latour have succeeded in constructing induction motors whose power 

 factor closely approaches unity at all loads, and which also possess 

 certain other remarkable peculiarities. Such induction motors are 

 known as compensated induction wwtors. The advantages which they 

 possess over ordinary induction motors have, however, been only 

 gained by a sacrifice of simplicity of construction. 



Although the researches of Heyland and Latour are comparatively 

 recent dating back to 1900 only yet the most prominent feature 

 of their compensated induction motors a rotor having a commutator 

 and resembling in every respect (except as regards position and 

 number of brushes) the armature of a continuous-current machine 

 is a device of much older date, having been patented as far back 

 as 1888 by Wilson in England, and in 1891 by Gorges in Germany. 

 Although Gorges gave a sketch of the theory of such motors in 1891, 

 there is no doubt that the possibilities presented by the use of a 

 commutator rotor were by no means fully realized at that time, and 

 it was only by the later labours of Heyland and Latour that this 

 type of motor was once more brought into prominence. 



Imagine a stator wound for 2 P poles, and into this stator let 



