Controller Overtemperature (Internal)

What does OH4 mean?

The controller's internal temperature has exceeded its safe operating limit. This indicates that the controller is experiencing excessive load, has insufficient cooling, or its internal fan is failing. Sustained internal overtemperature will lead to derating, thermal shutdown, and reduced lifespan of internal components.

• Blocked or dirty cooling fins and heatsinks, restricting airflow within the controller's enclosure.
• Malfunctioning or failed internal cooling fan, indicated by no audible operation or reduced airflow.
• High ambient temperature in the control cabinet exceeding the drive's specified operating range (e.g., >40°C).
• Excessive drive loading (e.g., motor current exceeding nominal, high switching frequency P1-03) for prolonged periods.
• Inadequate cabinet ventilation or incorrect sizing of the enclosure's cooling system (e.g., fan, air conditioner).

Click steps to track your progress.

1. 1

   Power down the drive, wait for it to cool, then clean any dust or debris from the controller's heatsink and cooling fan grilles using compressed air.

2. 2

   Verify the internal cooling fan is operating correctly; check for audible fan noise, airflow direction, and measure fan speed if applicable.

3. 3

   Measure the ambient temperature inside the control cabinet using a thermometer and ensure it is within the drive's specified operating limits.

4. 4

   Reduce the motor load or adjust the switching frequency (P1-03) if permissible, to decrease internal heat generation.

5. 5

   Inspect the control cabinet's ventilation system (e.g., filters, fans) for blockages or failures, ensuring proper airflow is maintained.