Find rotor stator loss in a 3 phase delta connected induction motor?
For an induction motor, the motor input power is equal to the mechanical power developed in the rotor plus the stator copper loss plus the rotor copper loss plus the iron loss.

The rotor copper loss is the mechanical power developed in the rotor multiplied by per-unit slip. Per-unit slip is (synchronous speed minus rotor speed) divided by synchronous speed.