A balanced three-phase supply is given to a -pole, , wound rotor induction motor with Y-connected stator and rotor windings. The motor is driving a constant torque load. With shorted sliprings, the machine runs at 1476 rpm.

When an external non-inductive resistance of  per phase is connected in series in the rotor circuit, the steady-state speed drops to 1404 rpm.

Neglecting rotational losses, the actual per phase rotor winding resistance is           

(Round off to two decimal places)

The parameter of an equivalent circuit of a three-phase induction motor affected by reducing the rms value of the supply voltage at the rated frequency is

The figure shows the per-phase equivalent circuit of a two-pole three-phase induction motor operating at 50 Hz. The “air-gap” voltage,  across the magnetizing inductance, is 210 V rms, and the slip, s, is 0.05. The torque (in Nm) produced by the motor is __________.

An 8–pole, 3–phase, 50Hz induction motor is operating at a speed of 700rpm. The frequency of the rotor current of the motor in Hz is _______________.

A 4-pole induction motor, supplied by a slightly unbalanced three-phase 50Hz source, is rotating at 1440rpm. The electrical frequency in Hz of the induced negative sequence current in the rotor is  

A two-phase load draws the following phase currents: , . These currents are balanced if  is equal to

A balanced three-phase voltage is applied to a star-connected induction motor, the phase to neutral voltage being V. The stator resistance, rotor resistance referred to the stator. Stator leakage reactance, rotor leakage reactance referred to the stator and the magnetizing reactance are denoted by  and  respectively. The magnitude of the starting current of the motor is given by:

A 440 V, 50 Hz, 6 poles and 960 rpm star connected induction machine has the following per phase parameters referred to the stator:

The magnetizing reactance is very high and is neglected. The machine is connected to the 440V, 50 Hz supply and a certain mechanical load is coupled to it. It is found that the magnitude of the stator current is equal to the rated current of the machine but the machine is running at a speed higher than its rated speed. Find the speed at which the machine is running. Also find the torque developed by the machine.

A three-phase slip ring induction motor is fed from the rotor side with stator winding short circuited. The frequency of the currents flowing in the short-circuited stator is