CPU Communication Error

What does E22 mean?

This fault occurs when there is a communication failure between the two internal CPUs within the inverter. Such a failure prevents coordinated operation and leads to an inverter trip, indicating a critical internal control issue.

• Transient power disturbance or voltage ripple affecting internal CPU power rails (e.g., 5VDC or 3.3VDC).
• Electromagnetic interference (EMI) ingress affecting internal communication buses due to poor grounding or shielding practices.
• Hardware failure of an internal CPU component or communication bus driver chip.
• Firmware corruption on one of the CPUs preventing proper initialization or inter-processor handshake.
• Severe operating conditions (e.g., extreme vibration) causing internal board connection issues.

Click steps to track your progress.

1. 1

   1. Cycle power to the inverter completely (remove main AC supply for at least 30 seconds), then reapply to reset internal CPUs.

2. 2

   2. Verify input supply voltage (VAC) stability at the inverter terminals (R, S, T) using a multimeter; check for significant sags or surges.

3. 3

   3. Inspect inverter grounding connections (PE terminal) for integrity and low impedance (typically <1 Ω to earth ground).

4. 4

   4. Isolate potential sources of EMI by temporarily disabling adjacent high-frequency switching devices or ensuring proper separation of power and control wiring.

5. 5

   5. If the error persists after power cycling, consider a firmware re-flash (if supported) or replacement of the inverter's control board.