Solution:

• No load test is performed when rotor rotates with synchronous speed and there is no load torque. This test is similar to the open circuit test on transformer.
• Actually, to achieve synchronous speed in an induction motor is impossible. The speed is assumed to be synchronized. The synchronous speed can be achieved by taking slip = 0 which creates infinite impedance in the rotor branch.
• During the no load test the energy consumed will be used to meet the core losses and the friction and windage losses.
• Rotor copper loss at no load is very less that its value is negligible.

• The diagram shows how the energy supplied to the motor is utilized and different losses in the motor.

  

• Power input = core loss ?? copper loss windage and friction loss
• Core loss occur only in stator, because at no load slip is very small , so frequency of induced emf in rotor will be extremely small.