Cooling fan
Common VFD, drive, UPS, and cabinet overheating failure point.
Siemens SINAMICS G120X Fault Codes
The Siemens SINAMICS G120X is a purpose-built VFD for pump, fan, and HVAC applications rated 0.75-630 kW. Like other SINAMICS drives, it uses F-codes (faults that require acknowledgment) and A-codes (alarms, informational). Codes display on the BOP-2 operator panel or through TIA Portal.
G120X Fault Code Table
| Code | Fault Description | Common Cause | Action |
|---|---|---|---|
| F00001 | Overcurrent | Motor overload, short circuit | Check motor winding, accel time |
| F00002 | Overvoltage | Regenerative energy from load | Add brake resistor or adjust ramp |
| F00003 | Undervoltage | Low supply voltage | Check input voltage |
| F00004 | Drive overtemperature | Ambient temp high, cooling blocked | Clean fins, check fan |
| F00011 | Motor overtemperature | Motor thermal model exceeded | Check motor load and cooling |
| F00012 | Overcurrent (software) | Motor current limit exceeded | Check load, increase ramp time |
| F00021 | Ground fault | Motor winding or cable ground fault | Megger test motor |
| F00025 | Load imbalance | Unbalanced motor current | Check motor winding resistance |
| F00051 | Parameter error | RAM fault or EEPROM | Restore defaults, reload parameters |
| F00052 | Power stack fault | IGBT or power module fault | Check DC bus and IGBT |
| F00101 | Power unit error | Internal fault | Contact Siemens support |
| F07801 | Motor stall | Motor jammed or locked rotor | Check mechanical load |
| F07900 | Motor blocked | No rotation detected | Check shaft and load |
| A07010 | Drive overtemperature warning | Approaching thermal limit | Improve cooling before fault |
Most Common G120X Faults
F00001 - Overcurrent
Most common fault on pump and fan applications. The G120X has auto-tuning for motor data - verify motor parameters match nameplate (P304 volts, P305 current, P307 power). Increase acceleration ramp time (P1120) to reduce inrush.
F00004 - Drive Overtemperature
G120X is rated -10 degrees C to 50 degrees C. Clean cooling fins with compressed air. The G120X has internal fans - verify they spin up on power application. Check thermal sensor reading via diagnostics menu (r0037).
F00021 - Ground Fault
Perform insulation test on motor cable with megohmmeter. For long cable runs (>100m), install output reactor. Check motor frame ground connection.
F00002 - Overvoltage
On pump/fan applications, rapid deceleration causes motor to regenerate energy back into the drive. Extend deceleration ramp time (P1121) or install dynamic braking resistor. Check for voltage spikes on supply.
Parts Commonly Needed
| Part | Notes |
|---|---|
| BOP-2 operator panel | Plug-in display for fault reading |
| Cooling fan | Internal fan - match G120X size |
| Power stack module | Only for IGBT failure confirmed by Siemens |
| Input choke | Reduces harmonic distortion |
| Output reactor | Required for long cable runs |
Technician Tips
When diagnosing VFD faults, always check the drive’s fault history before resetting. Modern drives store the last 5-10 faults with the drive state at the time (running, accelerating, decelerating, stopped). An overcurrent fault that occurs only during acceleration points to incorrect motor data or mechanical binding. The same fault during deceleration suggests regeneration issues. A ground fault that clears after disconnecting the motor and returns when reconnected means the motor or cable insulation has failed.
Prevention: Schedule annual infrared scanning of drive cabinets. Loose power connections and failing capacitors produce heat long before they cause faults. A 5-minute scan can prevent hours of unplanned downtime.
Need Replacement Parts?
Before ordering, match the drive part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
Pro tip: G120X supports BICO (Binector-Connector) parameterization for complex control schemes. When all mechanical and electrical causes are ruled out, use STARTER or TIA Portal to export a complete parameter backup before resetting - valuable for comparing pre- and post-fault parameters.