Question

The type of single-phase induction motor, expected to have the maximum power factor during steady state running condition, is

• A. split phase (resistance start).
• B. shaded pole.
• C. capacitor start.
• D. capacitor start, capacitor run.

Hint:

Capacitor start, capacitor run motors have the highest power factor in steady-state running conditions because both starting and running capacitors improve the motor's performance.

Answer 1

The Correct Option is D

Step 1: Understanding Power Factor in Induction Motors.
In single-phase induction motors, the power factor typically varies based on the type of motor and its starting method. The power factor is generally low during the startup phase and increases when the motor reaches steady state. The type of motor and the starting mechanism play a critical role in determining the steady state power factor. Step 2: Explanation of the Options.
- (A) split phase (resistance start): This type of motor typically has a lower power factor compared to capacitor-based motors.
- (B) shaded pole: These motors are low-efficiency motors and typically have a low power factor.
- (C) capacitor start: This type of motor has a higher power factor compared to other types, but not as high as the capacitor start, capacitor run motor.
- (D) capacitor start, capacitor run: This motor type has the highest power factor during steady state because both starting and running capacitors are used, improving the phase difference between current and voltage. Step 3: Conclusion.
The correct answer is (D) capacitor start, capacitor run, as it provides the highest power factor in steady state conditions.