When the machine is fully loaded.

When the machine is running under no-load.

When the armature is short-circuited.

When the prime mover is turned off.

Similar to the locked rotor test, maximum slip is attained, revealing efficiency directly.

The motor drives a variable load, showing only core losses. 

The motor is connected to a DC generator that acts as a variable mechanical load, allowing measurement of performance under real working conditions. 

Because the stator windings are short-circuited to force the motor to run at full torque.

Starting conditions are simulated where slip is 100% and rotor current is maximum. 

The stator windings are disconnected to measure only the rotor parameters.

The rotor runs at synchronous speed, minimizing current flow in the rotor.

The test measures core losses when the rotor is stationary.

The motor runs under heavy mechanical load, maximizing slip and rotor current.

The rotor current is very small, so most input power is used to overcome core losses and provide magnetizing current. 

The stator windings are reconnected during the test to measure winding resistance directly.

The rotor is locked, forcing maximum current through the rotor circuit.