Final answer:
OPTION A.Single phasing is a serious issue exclusive to three-phase motors caused by the loss of one phase, leading to unbalanced currents, excessive heat, and motor damage.
Step-by-step explanation:
The question concerns a serious problem unique to three-phase motors. The correct answer is A) Single phasing. Single phasing occurs when one of the three phases becomes disconnected. The motor will continue to run using the remaining two phases, which can lead to motor damage due to unbalanced currents and excessive heat. Issues like voltage imbalance, overcurrent, and phase reversal can occur in both single-phase and three-phase motors, making them not exclusive to three-phase motors.
In a three-phase motor, all three phases work together, providing a consistent level of power. Unlike single-phase motors, which can experience more significant fluctuations in power delivery, a three-phase system is more balanced and efficient. However, should one phase fail, the system's symmetry is disrupted, leading to single phasing which can quickly cause motor overheating and potentially result in motor windings' failure.