Siemens · AC Drives & VFDs
Siemens SINAMICS G120 repair
Siemens SINAMICS G120 control units and power modules diagnosed and repaired, with parameters saved first, by engineers on MachineryFix.
Cost confirmed before any work starts · Warranty of 30 days to 6 months
About this model
The Siemens SINAMICS G120
The SINAMICS G120 is Siemens' modular AC drive: a control unit (such as the CU240E-2 or CU250S-2) clipped onto a power module (such as the PM240-2). It replaced the MICROMASTER 440 in many plants and now runs pumps, fans, conveyors, mixers and machine axes across Indian industry.
Because the control unit and power module are separate, a G120 fault is first narrowed down to one or the other. A control unit fault often leaves the power module healthy, and the reverse; a memory card or the operator panel can hold the parameters, which makes recovery much quicker when one part has to be replaced.
Engineers on MachineryFix work on G120 control units and power modules. An engineer can come to the plant from our Hyderabad base, and from anywhere in India the drive or module can be sent to MachineryFix for routing to an engineer.
Common faults
What goes wrong on the SINAMICS G120
Power unit overcurrent
Failed IGBTs, a shorted motor cable or a motor winding fault. The motor and cable are tested with the power module disconnected before power is reapplied.
DC link overvoltage
Regenerated energy during deceleration with no braking resistor, or a ramp-down time that is too short for the load's inertia.
Heatsink overtemperature
Blocked cooling paths, a failed fan in the power module, or a cabinet that runs hot in summer.
Control unit faults
A control unit that won't boot, loses communication on PROFINET or PROFIBUS, or reports internal errors. The memory card and parameter backup decide how fast recovery is.
Line phase failure
A missing supply phase, a blown input fuse or a failing rectifier in the power module.
Fault codes
SINAMICS G120 fault codes
Codes and names as Siemens lists them; the explanations are ours. Check the manual for your firmware version before acting on a code.
| Code | Name | What it usually means |
|---|---|---|
| F07801 | Motor overcurrent | Motor current exceeded the limit: check the load, the acceleration ramp and motor data before suspecting the power module. |
| F07900 | Motor blocked | The motor is stalled at the torque limit: a jammed load, a brake that hasn't released, or limits set too low. |
| F07011 | Motor overtemperature | The motor temperature sensor or model reports overheating: overload, blocked motor cooling or a sensor fault. |
| F30001 | Power unit: overcurrent | The power module detected overcurrent: often a short in the motor or cable, or a failing IGBT. |
| F30002 | Power unit: DC link overvoltage | The DC link voltage is too high, usually during braking. Check the ramp-down time and the braking resistor. |
| F30003 | Power unit: DC link undervoltage | The DC link voltage is too low: a supply dip, a missing phase or an input stage problem. |
| F30004 | Power unit: heat sink overtemperature | The power module is too hot: check the fan, airflow and cabinet temperature. |
| F30005 | Power unit: overload I2t | The power module has been overloaded for too long: the load exceeds what the module is sized for, or the duty cycle is too heavy. |
| F30011 | Line phase failure | A supply phase is missing or badly unbalanced: check the incoming supply and fuses. |
F07801
Motor overcurrent
Motor current exceeded the limit: check the load, the acceleration ramp and motor data before suspecting the power module.
F07900
Motor blocked
The motor is stalled at the torque limit: a jammed load, a brake that hasn't released, or limits set too low.
F07011
Motor overtemperature
The motor temperature sensor or model reports overheating: overload, blocked motor cooling or a sensor fault.
F30001
Power unit: overcurrent
The power module detected overcurrent: often a short in the motor or cable, or a failing IGBT.
F30002
Power unit: DC link overvoltage
The DC link voltage is too high, usually during braking. Check the ramp-down time and the braking resistor.
F30003
Power unit: DC link undervoltage
The DC link voltage is too low: a supply dip, a missing phase or an input stage problem.
F30004
Power unit: heat sink overtemperature
The power module is too hot: check the fan, airflow and cabinet temperature.
F30005
Power unit: overload I2t
The power module has been overloaded for too long: the load exceeds what the module is sized for, or the duty cycle is too heavy.
F30011
Line phase failure
A supply phase is missing or badly unbalanced: check the incoming supply and fuses.
First checks
What to check before calling an engineer
Safe for plant staff
- Read the active fault and the fault buffer on the operator panel or in the engineering software.
- Note whether the fault appears at power-up, at start, during running or while stopping.
- Check the power module's fan and the cabinet's filters and temperature.
- If the drive has a memory card, keep it with the drive; it may hold the parameters.
Leave to a specialist
- Swapping a control unit or power module, which needs the parameters handled and the firmware checked.
- Any work inside the power module after isolation, before the DC link has discharged.
- Changing control mode, motor data or safety functions (Safety Integrated) on a running machine.
Getting it fixed
How to get a SINAMICS G120 repaired
Technicians work onsite from our Hyderabad base and travel to plants across India; anything that can be removed can also be sent to MachineryFix from anywhere in the country. The diagnosis and repair cost are confirmed before any work starts.
Warranty. Repairs carry a warranty of 30 days to 6 months, depending on the item and the repair; the exact term is confirmed before work starts.
FAQ
SINAMICS G120 repair questions
How do I know whether the control unit or the power module has failed?+
The fault code and the drive's behaviour usually point to one. Power unit faults (F30xxx) generally relate to the power module; boot and communication failures to the control unit. Testing each part separately confirms it before anything is replaced.
Can a G120 replace a MICROMASTER 440?+
Often, yes, and it is a common migration. The settings are transferred and checked against the old drive's parameter list, and the wiring differences between the two are handled during installation.
Can I send just the power module?+
Yes. Send the module with the control unit model and fault code to MachineryFix and it is routed to an engineer who works on G120s. The diagnosis and repair cost are confirmed before any work starts.
Is there a warranty on the repair?+
Yes. Repairs carry a warranty of 30 days to 6 months, depending on the item and the repair; the exact term is confirmed before work starts.
Same manufacturer
Other Siemens AC Drives & VFDs
Siemens and SINAMICS G120 are named only to identify the equipment. MachineryFix is not affiliated with or endorsed by Siemens.
SINAMICS G120 down?
Send the fault code and what the machine was doing. We'll match an engineer who works on it.