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Siemens SINUMERIK Controller
System · Intermediate · 30-120 minutes
Siemens 840D 20095 - Axis illegal torque, current torque
Alarm 20095 occurs during brake test operation when the axis cannot generate sufficient holding torque to meet the test requirements defined in the brake test parameters. This indicates a mismatch between the demanded holding torque specification and the actual motor/drive capability under current machine parameterization.
20095
Siemens 840D 20095 - Axis illegal torque, current torque
Axis illegal torque, current torque
Siemens SINUMERIK 840D alarm 20095: Axis illegal torque, current torque. This alarm indicates a program or channel-level error on the SINUMERIK control. The part program or machine function cannot be executed as commanded.
Root Cause Summary
Alarm 20095 occurs during brake test operation when the axis cannot generate sufficient holding torque to meet the test requirements defined in the brake test parameters. This indicates a mismatch between the demanded holding torque specification and the actual motor/drive capability under current machine parameterization.
Safety
- Refer to Siemens documentation
- Ensure qualified technician performs repairs
Causes and Fixes
- 1
Access Diagnostics > Axis > [Axis name] > Motor Data and verify the continuous torque rating (typically displayed as M_cont or Mn). Compare against the active brake test torque parameter.
Do not proceed with brake test if motor continuous rating is borderline.
- 2
Navigate to Machine > CNC > Axis > [Axis] > Motor/Drive and check MD34010 (BRAKE_TEST_TORQUE) or machine-specific equivalent. Reduce this value to 85-90% of motor continuous torque rating.
- 3
Verify MD34004 (BRAKE_TEST_TIME) is set appropriately; excessive holding duration may cause thermal overload and current limiting. Recommend 2-5 second test cycles.
- 4
Perform brake test retry after parameter adjustment and monitor actual torque feedback in Diagnostics > Actual Values > Torque/Current.
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