What happens to a three-phase motor if one phase were to fail?

In the event of a failure in one phase of a three-phase motor, the motor experiences an imbalance in the electrical supply. This occurs because three-phase motors are designed to operate with balanced loads across all three phases. When one phase fails, the remaining two phases overload, attempting to compensate for the missing phase, which results in increased current draw.

This situation can cause the motor to overheat due to the excessive current flow, which can lead to insulation breakdown and potential damage to the motor windings. Over time, the increased thermal stress can significantly reduce the motor's lifespan or cause complete failure.

While the motor may still attempt to run, it will not be efficient and can create additional mechanical stress that can lead to further complications, including physical damage. This explains why understanding the impact of a phase failure is critical for maintaining the longevity and safe operation of three-phase motors.