Lenze i500 Error Code OH

Lenze PLC & VFD Critical Temperature

Model: i500 | Code: OH

Applicable Systems
i500

Symptoms

Heatsink overtemperature. The drive heatsink temperature has exceeded the critical limit. The driveimmediately stops to protect the power semiconductors.

Possible Causes

  • Drive cooling fan failed: not running or seized bearing
  • Ambient temperature exceeding drive specification (typically 50C max)
  • Drive cabinet ventilation inadequate or filter blocked
  • Drive operating at sustained overload current
  • Heat sink severely contaminated with dust or oil

Troubleshooting Steps

  1. Step 1: Check the equipment status and fault indicators to confirm the active fault code
    Fault indicator or HMI displays code OH as active
  2. Step 2: Verify all electrical connections, wiring harnesses, and connector seating
    All connections secure, no corrosion, loose pins, or damaged wires
  3. Step 3: Check ambient temperature around the equipment with a thermometer
    Temperature is within the specified operating range (typically 10-40 degrees C)
  4. Step 4: Inspect cooling fan operation, airflow paths, and heat sink for dust or blockage
    Fan operating normally, airflow unobstructed, heat sink clean
  5. Step 5: Verify equipment load and duty cycle are within rated capacity
    Load and duty cycle within manufacturer specifications
  6. Step 6: Allow equipment to cool below the alarm threshold before attempting reset
    Temperature readings return to normal operating range
  7. Step 7: Reset the fault after the temperature has normalized: press RESET on the HMI
    Fault clears and equipment resumes operation

How to Reset

To reset: 1) Resolve the temperature issue (fix cooling, reduce load). 2) Wait for temperature to drop below alarm threshold. 3) Press RESET on the HMI. Caution: Repeated overtemperature degrades component lifetime.

Frequently Asked Questions

  • Q: What does fault code OH mean on the Lenze i500?

    Fault OH indicates a temperature-related fault. The equipment has detected a temperature exceeding the safe operating limit. Check the cooling system, ambient temperature, and equipment loading.

  • Q: Can I continue operating the equipment with fault OH active?

    No. The equipment has detected a fault condition and has taken protective action (typically stopping or derating). Continuing to operate without fixing the root cause may cause further damage. Always investigate and fix the fault before resuming operation.

Related Lenze Fault Codes

Source: Lenze i500 Frequency Inverter Operating Instructions, Lenze Documentation

Category: PLC & VFD