Lenze i500 Error Code OH4

Lenze PLC & VFD Minor Temperature

Model: i500 | Code: OH4

Applicable Systems
i500

Symptoms

Heatsink overtemperature alarm. The drive heatsink temperature has exceeded the warning threshold but not thecritical limit. The drive continues to operate with a warning.

Possible Causes

  • Drive cooling fan speed reduced due to bearing wear
  • Ambient temperature gradually rising toward limit
  • Drive load increasing, causing higher heat dissipation
  • Heat sink dust accumulation starting to affect thermal performance

Troubleshooting Steps

  1. Step 1: Check the equipment status and fault indicators to confirm the active fault code
    Fault indicator or HMI displays code OH4 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 OH4 mean on the Lenze i500?

    Fault OH4 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 OH4 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