A recent measurement added for this motor indicates a voltage sag of more than 10% below this motor’s rated voltage.
Operating motors below their rated voltage causes the motor to draw higher current than would otherwise be required to meet the load’s torque requirements. The increased current draw triggers higher I²R losses, causing the motor to operate at higher temperatures. Without timely correction, this excess heat can damage the motor’s winding insulation and lead to bearing lubrication failure. The longer this motor is exposed to low voltages, the more damage the motor will incur.
Since torque production is proportionate to voltage, a motor may fail to produce adequate starting torque during a voltage sag, causing its starter or control circuit to trip offline. If the motor is already running, it may be more susceptible to stalling due to the inability to produce sufficient torque for the load.
Suggested actions
- Validate measurements; ensure measurements are taken phase-to-phase, not phase-to-neutral.
- Determine duration and frequency of voltage sags. Is the sag temporary? Does it correlate with other equipment turning on or off?
- If temporary, investigate whether your facility would benefit from adding capacitance (e.g., UPS) to supplement intermittent voltage sags.
- If permanent, trace the cause. E.g., is your utility supplying voltage less than the rated amount per your tariff? Is this circuit overloaded?