Squirrel cage rotor consists of a laminated cylindrical core having parallel slots on its outer periphery. One copper or aluminum bar is placed in each slot. All these bars are joined at each end by metal rings called end rings. This forms a permanently short-circuited winding which is indestructible. The entire construction (bars and end rings) resembles a. squirrel cage and hence the name. The rotor is not connected electrically to the supply but has current induced in it by transformer action from the stator.
While wound rotor consists of a laminated cylindrical core and carries a 3-phase winding, similar to the one on the stator.