In this type of rotor, the rotor drum is provided with a number of circular holes, which are parallel to the shaft.
Solid copper or aluminium bars are placed in these holes and all bars are welded to the two end rings to establish bars electrical contact between them.
The bars and the end rings together look like a cage and hence such a rotor is called cage rotor or squirrel, Cage rotor.
Due to short-circuiting of bars through end rings, rotor terminals are not accessible to the user.
So no external connection can be made to the cage type rotor, therefore it is not possible to connect external resistance to the rotor.