Siemens SINAMICS G120 Error Code F31155

Siemens PLC & VFD Major Encoder

Model: SINAMICS G120 | Code: F31155

Applicable Systems
S7-1200 S7-1500 S7-300 S7-400 LOGO! SINAMICS

Symptoms

Encoder ground fault: encoder circuit leakage to ground.

Possible Causes

  • Encoder cable insulation breakdown
  • Encoder internal ground fault
  • Wiring fault

Troubleshooting Steps

  1. Step 1: Megger test encoder cable to ground
    Insulation > 1 MOhm
  2. Step 2: Inspect encoder wiring
    No ground fault path
  3. Step 3: Replace encoder if internal fault
    New encoder operates correctly

How to Reset

Reset via operator panel after encoder ground fault is repaired.

Related Siemens Fault Codes

Source: Siemens SINAMICS G120 List Manual

Category: PLC & VFD