4. Theory In an induction motor, if full voltage is applied across the stator terminals with the rotor not allowed to rotate, about six to eight times its full-load current will flow in the circuit. Blocked-rotor test is conducted at a reduced voltage V S so that current, I S equals to only the full-load current flow through the circuit. The applied voltage V S under blocked rotor condition is, therefore, about one-sixth to one-eighth of the normal voltage. At this reduced voltage the current I 0S flowing through the parallel branch is very small, and can be neglected. R e ’ and X e ’ are stationary resistence and reactance in series connected across the applied voltage, V S . If W S is the input power under blocked-rotor condition, I S is the current and cos φ S is the power factor, then as a result: