Voltage and current imbalance calculator

Enter three line voltages or currents and get the percentage imbalance using the NEMA method.

What this means

Small voltage imbalance causes much larger current imbalance and heating in three phase motors. Check the supply first. Rolling the motor leads one position and remeasuring current helps tell whether the problem follows the supply or stays with the motor.

Formula used

  • Average = (L1 + L2 + L3) ÷ 3
  • % imbalance = largest deviation from average ÷ average × 100

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