E020
Perkins
Incorrect Phase Rotation / Phase Sequence Fault
Controller displays E020 and indicates phase sequence / rotation error
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Incorrect connection of generator output cables, Miswired ATS output, Controller phase sensing wiring reversed
How to Fix / Troubleshooting
Safety: Always isolate the generator and ATS before altering any power connections. Use lockout/tagout procedures.
- Verify phase rotation: Use a phase rotation meter at the generator terminals and at the load side of the ATS. Confirm the sequence (e.g., L1‑L2‑L3) matches site requirements.
- Check power cable connections: In the generator terminal box, ensure that the labeled phases from the alternator are correctly connected to the outgoing cables.
- Inspect controller sensing: Confirm that the controller’s voltage sensing leads are connected to the correct phases and in the correct order.
- Correct wiring: If rotation is reversed, swap any two phases at the generator output or ATS (following site standards) to restore correct sequence.
- Reset alarm: After corrections, clear E020 and perform a test transfer with the ATS.
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Repair Difficulty
Medium
3/5
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