Cause: CPU error comes when the central processing unit (CPU) – the "brain" of the inverter – has detected an internal error or malfunction. This prevents the drive from executing its program and controlling the motor, essentially making it inoperable.

er3 CPU error fault in fuji FRENIC MEGA drive indicates CPU error.  This means the CPU has encountered a fundamental problem that it cannot recover from. This could be a software-related issue (corrupted instruction, program crash) or, more commonly, a hardware malfunction within the CPU itself or its supporting circuitry.

Troubleshooting Steps

• Power Cycle the Drive: Completely remove all power from the drive (main input power) & wait 5 min then power-up.
• Check if appropriate noise control measures have been implemented.
• Look for any signs of physical damage to the drive casing or the cooling fans.