Formula variables
- VAB, VBC, and VCA are measured line-line voltages.
- Average voltage is the arithmetic mean of the three readings.
- Maximum deviation identifies the phase pair farthest from average.
- Imbalance percent is a preliminary power-quality screen.
Assumptions
- The calculator uses three line-line voltage readings from the same operating condition.
- Imbalance percent is based on the maximum deviation from average voltage.
- The output is a screening value for review, not a diagnosis of the cause.
- This calculator does not diagnose the cause, approve motor operation, or replace power-quality investigation.
Examples
600 V motor feed. Readings of 600 V, 592 V, and 607 V estimate about 1.28 percent imbalance.
Review workflow. Use the result with load balance, source condition, and motor manufacturer tolerance review.