Slip ring induction motor is one of the types of 3 phase induction motor and is a wound rotor motor type.
Slip ring induction motor rotor connection.
The working principles and stator construction of the slip ring induction motor are exactly the same as that of the squirrel cage motor.
However the rotor construction of the slip ring motor is quite interesting.
The rotor is wound for the same number of poles as that of the stator.
Adjusting the resistance allows control of the speed torque characteristic of the motor.
Instead of bars in this motor three windings are used.
The three terminals of star connected rotor windings are brought out and are connected to the external resistors through the slip ring.
It consists laminated cylindrical core which has a semi closed slot at the outer periphery and carries three phase insulated winding.
This construction of the rotor is aimed at reducing the phase difference.
The motor which employing the wound rotor is known as a slip ring induction motor or phase wound motor.