Lenze i500 Error Code OH8

Lenze PLC & VFD Major Motor

Model: i500 | Code: OH8

Applicable Systems
i500

Symptoms

Motor temperature sensor fault. The motor PTC or PT100 temperature sensor signal is invalid. The drive cannotmonitor motor temperature and stops as a precaution.

Possible Causes

  • Motor PTC/PT100 sensor cable broken or disconnected
  • PTC sensor open circuit: element failed
  • PT100 sensor short circuit: cable insulation damage
  • Drive temperature sensor input circuit fault

Troubleshooting Steps

  1. Step 1: Check the equipment status and fault indicators to confirm the active fault code
    Fault indicator or HMI displays code OH8 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 motor cable connections at drive output terminals for correct phase sequence and tightness
    Cables securely connected, phase sequence correct, no loose terminals
  4. Step 4: Measure motor winding insulation resistance with a megger (500V DC minimum)
    Insulation resistance above minimum value (typically > 1 Megaohm)
  5. Step 5: Verify drive parameter settings match motor nameplate data (current, voltage, power, RPM)
    All motor nameplate parameters correctly entered in drive
  6. Step 6: Inspect motor for mechanical overload, bearing seizure, or driven equipment jam
    Motor rotates freely, no mechanical binding or excessive load
  7. Step 7: Reset the fault after fixing the root cause: clear the fault via HMI or power-cycle
    Fault clears and drive resumes normal operation without recurrence

How to Reset

To reset: 1) Identify and fix the root cause described in the fault symptoms. 2) Press RESET on the HMI or controller, or power-cycle the equipment. 3) If the fault recurs, contact manufacturer service. Caution: Document the fault code and context before resetting.

Frequently Asked Questions

  • Q: What does fault code OH8 mean on the Lenze i500?

    Fault OH8 on the Lenze i500 indicates: Motor temperature sensor fault. The motor PTC or PT100 temperature sensor signal is invalid. The drive cannot monitor motor temperature and stops as a precaution. Refer to the equipment manual and manufacturer support for specific troubleshooting steps.

  • Q: Can I continue operating the equipment with fault OH8 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