Running Winding in a Split Phase Motor

The running winding in a split-phase motor is responsible for providing the torque necessary to run the motor. It is designed to have specific characteristics that enable reliable and efficient motor operation. In this context, the correct option is B: low resistance and high inductance. Let's understand why this is the case.

Low Resistance

The running winding should have low resistance to minimize power losses and increase efficiency. When the motor is operating, current flows through the winding, and if the resistance is high, it will result in significant power dissipation in the form of heat. This heat can adversely affect the motor performance and lead to premature failure. Therefore, a low resistance winding is preferred to reduce power losses and enhance the motor's overall efficiency.

High Inductance

The running winding should have high inductance to create a phase shift between the current flowing through the running winding and the starting winding. This phase shift is essential for the split-phase motor to achieve the necessary torque to start and run. The high inductance of the running winding allows it to create a lagging current, which produces a rotating magnetic field that interacts with the starting winding's magnetic field. This interaction generates the necessary torque to start the motor and keep it running.

Explanation of Other Options

a) High resistance and low inductance: This option is incorrect because high resistance in the running winding would lead to excessive power losses and reduced efficiency. Low inductance would also prevent the necessary phase shift, affecting the motor's starting and running torque.

c) High resistance as well as high inductance: This option is not suitable because high resistance would still result in significant power losses, while high inductance alone would not provide the required phase shift for starting and running the motor efficiently.

d) Low resistance as well as low inductance: This option is also incorrect because low resistance would lead to excessive power losses, and low inductance would not provide the necessary phase shift for starting and running the motor.

Conclusion

To summarize, the running winding in a split-phase motor should have low resistance to minimize power losses and high inductance to create the required phase shift for efficient motor operation. These characteristics ensure reliable starting and running torque, enhance motor performance, and improve overall efficiency.