Controller displays “Phase Imbalance” or “Voltage Imbalance” on three-phase Eaton standby generators.

Safety first: Open the generator output breaker and isolate from the transfer switch before working on power connections.

Steps:

• Measure phase voltages: With the generator running and no load, measure L1-L2, L2-L3, and L3-L1. They should be within a few percent of each other.
• Inspect connections: Tighten all alternator output lugs and bus connections. Look for discoloration or heat damage indicating a loose joint.
• Check load balance: If imbalance occurs only under load, review the distribution of loads on the Eaton transfer switch and downstream panels. Rebalance circuits to even out phase currents.
• Alternator test: If one phase remains low with no load and tight connections, the alternator winding or AVR sensing may be faulty and require professional testing or replacement.