SMA Sunny Boy Error Code 901

SMA PLC & VFD Critical Safety

Model: Sunny Boy | Code: 901

Applicable Systems
Sunny Boy

Symptoms

PE connection fault. The protective earth (PE) connection is not detected or is faulty. This is a safetyhazard.

Possible Causes

  • PE conductor not connected or loose at inverter terminal
  • PE conductor broken or corroded
  • Building ground rod or earthing system fault
  • Inverter PE detection 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 901 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 the safety circuit continuity and all safety interlock switches
    Safety circuit complete, all interlocks engaged
  4. Step 4: Inspect the specific safety device referenced in the fault (door switch, light curtain, E-stop)
    Safety device functional, contacts clean and responsive
  5. Step 5: Verify the brake mechanism: check brake pad wear, spring tension, and air gap
    Brake pads within wear limit, spring tension correct, air gap within spec
  6. Step 6: Test the safety function by simulating the fault condition and verifying response
    Safety function responds correctly within specified time
  7. Step 7: Reset the fault after fixing the safety device or circuit: press RESET
    Fault clears and safety system returns to ready state

How to Reset

To reset: 1) Fix the safety device or circuit fault. 2) Clear the fault on the HMI or controller. 3) Press RESET. Caution: Never bypass safety devices.

Frequently Asked Questions

  • Q: What does fault code 901 mean on the SMA Sunny Boy?

    Fault 901 indicates a safety-related fault. A safety device or circuit has been triggered. Always investigate the root cause before resetting; never bypass safety devices.

  • Q: Can I continue operating the equipment with fault 901 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 SMA Fault Codes

Source: SMA Sunny Boy Inverter Installation and Operation Manual, SMA Official Documentation

Category: PLC & VFD