What occurs when one phase of a three-phase motor is lost?

When one phase of a three-phase motor is lost, the motor typically overheats and loses torque. In a three-phase system, the phases work together to create a rotating magnetic field that smoothly powers the motor. When one phase is lost, the remaining two phases continue to operate, but the motor is no longer balanced, resulting in an uneven magnetic field. This imbalance causes the motor to draw more current in an attempt to compensate for the lost phase, leading to overheating.

Additionally, the motor experiences a significant reduction in torque because it is not able to deliver the same power output as it would with all three phases functioning. The lack of torque can cause the motor to stall under load. This condition can not only affect performance but also lead to potential damage due to excessive heat generated by the overcurrent. Understanding these effects is crucial for diagnosing issues in three-phase motors and ensuring their proper operation and maintenance.