Question 1Electricity & Electronics - Assistant Engineer

The correct answer is C) inserting resistance into the rotor circuit. The speed of a slip ring induction motor can be controlled by inserting resistance into the rotor circuit. This changes the slip, which is the difference between the synchronous speed and the actual speed of the motor. Increasing the rotor resistance reduces the speed of the motor, while decreasing the resistance increases the speed. The other options are incorrect because: A) inserting resistance into the stator circuit does not control the motor speed, B) adjusting the governor linkage is for controlling the speed of a governor, not a slip ring induction motor, and D) changing the number of phases does not provide a means of speed control for this type of motor.