MOTCO " make Slipring Induction Motors are nearly the same as normal Induction motors, except that their rotors are wound with windings.
||2.2kw till 7.5kw
||3 Phase, 415V AC Supply.
||B3 Foot mounted, B5.
||IC01 Self Fan cooled.
||Rotor resistance start
When three phase potential is applied to the stator winding a rotating magnetic field will travel around the inside of the stator core in indentically the same manner as in a squirrel cage induction Motor. The speed of the rotating magnetic field is dependent on the number of stator poles and the frequency of the supply source.
This synchronous speed is found using the formula S = 120F ÷ P.
As the rotating field travels at synchronous speed, it cuts the wound rotor winding and induces voltages in these winding.
On starting, all the resistance of Rotor resistance starter is inserted in the circuit. With the increase in resistance in the Rotor circuit the impedance increases and therefore it might appear as though the rotor current would be less with the a resultant decrease in torque. This results in maximum interaction between the two field and a strong starting torque.
As the motor accelerated, steps of resistance are cut out of the Rotor resistance starter controller with all resistance cut out, the rotor slip ring are short circuited and the motor operate at rated speed in the same manner as a squirrel cage induction Motor.