A three-phase wound-rotor (slip-ring) induction motor. Unlike the cage machine, the rotor winding is brought out through slip rings to an external starting rheostat. Extra resistance in the rotor circuit raises the starting torque while limiting the inrush, and it also allows the speed to be lowered smoothly (more resistance means more slip). As the motor runs up, the rheostat is cut out. Such drives are used where a high starting torque and a smooth start under load are needed — cranes, hoists, mills. The model shows the torque M, the slip s and the added rotor resistance.
This page is a utility for simulating wound-rotor induction motor with starting rheostat (3-phase) online with specified initial values.
Using the model. The three stator switches start the motor — the scopes show the start-up transient. The three "rotor rheostat" sliders change the extra resistance in the rotor phases: increase it and the starting torque and slip rise (the speed drops); reduce it to zero and the motor runs up to nearly synchronous speed like a cage machine. Use the "load torque" slider to set the shaft load. The top scope shows the stator current I(stator), the middle one the rotor current I(rotor), and the bottom one the line voltage U(L1‑L2).
Comments