The speed of a single-phase motor is primarily determined by the number of stator windings and what other factor?

The speed of a single-phase motor is primarily determined by the number of stator windings and what other factor?

• A. Number of rotor windings
• B. Size of the armature
• C. Frequency of the applied voltage
• D. Volume of current applied

Answer: (C)

The speed of a single-phase motor is fundamentally determined by the frequency of the applied voltage because the motor's synchronous speed is directly related to the frequency. The formula for synchronous speed (in RPM) is given by \( 120 \times \text{Frequency} / \text{Number of poles} \). This highlights that as the frequency increases, the synchronous speed of the motor also increases, provided the number of poles remains constant. The number of stator windings does play a role in determining the characteristics of the motor, such as the torque and efficiency, but the speed itself is fundamentally tied to the frequency of the voltage applied. Other options, like the number of rotor windings and the size of the armature, do not have a direct relationship with the speed in the same way that frequency does. The volume of current applied impacts the motor's performance, such as startup torque and overheating, but it does not affect the speed directly. Thus, frequency is the key factor that primarily influences the operational speed of a single-phase motor.

The speed of a single-phase motor is fundamentally determined by the frequency of the applied voltage because the motor's synchronous speed is directly related to the frequency. The formula for synchronous speed (in RPM) is given by ( 120 \times \text{Frequency} / \text{Number of poles} ). This highlights that as the frequency increases, the synchronous speed of the motor also increases, provided the number of poles remains constant.

The number of stator windings does play a role in determining the characteristics of the motor, such as the torque and efficiency, but the speed itself is fundamentally tied to the frequency of the voltage applied. Other options, like the number of rotor windings and the size of the armature, do not have a direct relationship with the speed in the same way that frequency does. The volume of current applied impacts the motor's performance, such as startup torque and overheating, but it does not affect the speed directly. Thus, frequency is the key factor that primarily influences the operational speed of a single-phase motor.