AC MOTORS

Induction motors (1 & 3)
 Is one in which the motor field is induced by currents flowing through the stator. The rotor circuit has no connection whatsoever to supply the circuit. The power factor of this motor is lagging and operate with a lagging pf.

General types of 3 and 1 INDUCED MOTOR

a) Squirrel cage rotor type = its rotor is self contained and resembles a bird cage. The rotor conductors are permanently short circuited by end rings.

Speed characteristic: nearly constant or adjustable speed
Torque characteristic: in general it has medium starting torque
Uses: blower, compressor, pump, prime mover of generators

b) Wound rotor = its rotor has insulated coil of wire and resembles a DC armature. The rotor conductors are connected to slip rings and shorted through branches.

Speed characteristic: variable speed
Torque characteristic: high starting torque
Uses: hoist, crane, escalator, conveyor, elevator, etc.





CIRCUIT DIAGRAM