Generator display shows E19 and the unit shuts down; controller indicates a phase imbalance or single-phasing condition (for 3-phase models).

Safety first: Isolate the generator from all loads and utility. Use appropriate PPE when working on 3-phase systems.

• Measure phase voltages: With the generator running and no load, measure voltage between each phase pair and to neutral. Significant differences indicate a problem.
• Inspect connections: Tighten all output lug connections and inspect for burned or discolored terminals.
• Check stator continuity: With the generator off, measure resistance of each phase winding. An open or significantly different reading on one phase indicates a failed winding.
• Replace AVR or stator: If the stator is good but imbalance persists, replace the 3-phase AVR. If a winding is open, the alternator stator must be replaced or rewound.