TIIK INDUCTION MOTOR 



269 



The inability of the induction generator to deliver lagging 

 current is the principal objection to its use. Considerable kv-a. 

 in synchronous apparatus is required to supply the total quad- 

 rature current required. The distinct advantage of the induc- 

 tion generator is the fact that it does not hunt or drop out of 

 synchronism; it is simple and rugged, and when short-circuited 

 it delivers little or no power because its excitation at once becomes 

 zero. Its principal use seems to be in the development of small 

 water powers, where the cost of attendance would prohibit the 

 use of synchronous apparatus. The induction generator con- 

 nected to the water wheel does not need to be synchronized, 

 requires no direct-current excitation, and does not fall out of syn- 



.14 .12 .10 .08 .08 .04 .02 .02 .04 .06 .08 .10 .12 .14 



Fio. 250. Operating characteristics of induction machine as motor and as 



generator. 



chronisni. It delivers power if there is sufficient water; if not. 

 it merely runs idle as an induction motor. Such machines would 

 feed into a main irenerat inn Mation located in the vicinity and 

 SO could l>e under the occasional insj>ection of an operator. 



The induction ireneratnr is alsn very useful for braking purposes 



in railway work. If the induction motors be left connected 



i he line on a down irrade. any tendency of the train to 



them above synrlmnii.Mii will be accompanied by uenerator 



action. In addition to hrakirm the train, the uenerat<>i> pump 



jx.wer back into the line and so relieve the main ^eneratin^ 



m of some of its load. The machine therefore rcquir 

 complicated control apparatu> when used for regent > 



