////: INDUCTION MOTOR 



257 



Where a rheostat is used for starting duty only, the rotor 

 conductors may be connected to resistance grids within the 

 rotor itself. Such grids can be short-circuited by copper brushes 



FIG. 244. Westinghousc 1,200 hp., 580 r.p.m. induction motor driving a 

 Worthington centrifugal pump. 



operated by pushing a rod which protrudes from the center of 

 the rotor shaft. Such a rotor is shown in Fig. 245. This type 



Fio. 245. Rotor of in<lu< -ti>n motor having starting resistance within rotor. 



of rot 't be operated with tin- nrid> in circuit c<mi inu<u-ly 



because of the ditliculty of dissipating the heat which is developed 

 within the rotor, 



17 



