What occurs when an induction motor is subjected to a drop in frequency during operation?

When an induction motor experiences a drop in frequency during operation, the motor speed decreases. This phenomenon is primarily due to the relationship between the frequency of the AC power supply and the synchronous speed of the motor, which is determined by the formula:

[

\text{Synchronous Speed} (N_s) = \frac{120 \times \text{Frequency} (f)}{\text{Number of Poles} (P)}

]

As the frequency diminishes, the synchronous speed decreases correspondingly, which means the rotor of the induction motor must also operate at a lower speed to remain in sync with the changing magnetic field generated by the stator. Consequently, when the frequency drops, the motor cannot maintain its original speed and will operate at a lower speed until a stable operational frequency is restored.

The motor does not cease operation completely; rather, it continues to run but at a decreased speed, thus ruling out the other potential answers. Maintaining a constant voltage along with the reduced frequency could also lead to a condition called "voltage drop," which can affect the performance and efficiency of the motor but does not result in the motor stopping altogether.