CPU fault
Mitsubishi Electric · FR E700
What does E.5 mean?
This is a CPU fault that stops the inverter output when a communication fault occurs within the built-in CPU. Such an error indicates a critical internal processing issue, which can be influenced by external factors like electrical noise. Inverter operation is halted to prevent further damage or incorrect control.
Common Causes
- Internal data bus communication error within the CPU or between the CPU and peripheral chips.
- Instability of internal clock signals critical for CPU operation due to component drift or noise.
- Insufficient or fluctuating internal power supply voltage to the CPU and associated circuitry.
- Faulty firmware executing an illegal instruction or entering an infinite loop.
- Excessive ambient temperature causing thermal stress on CPU components.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Power cycle the inverter by disconnecting all input power for a minimum of 60 seconds to ensure a full reset of all internal logic.
- 2
Ensure the inverter's operating environment is within specified temperature limits (e.g., 0-50°C) and that cooling fans are operational.
- 3
Measure the stability of the 24VDC control power supply at designated terminals (e.g., PC/P24) to ensure it is constant.
- 4
Check for any external sources of electromagnetic interference (EMI) near the inverter's control section or communication lines.
- 5
Visually inspect the control circuit board for any physical damage, discoloration, or loose connections.