What causes Siemens SINUMERIK alarm 300721?

SINAMICS drive hardware fault requiring investigation. Drive parameter configuration error. Axis motor or feedback system fault triggering drive protection. Communication fault on the drive bus. Power supply issue affecting the drive module.

How do I fix Siemens SINUMERIK alarm 300721?

1. Check the SINAMICS drive for active fault codes in the diagnostics screen. 2. Power cycle the machine to clear transient faults. 3. Review SINAMICS parameters for the affected drive axis. 4. Check the SINUMERIK axis diagnostics for related NC alarms. 5. Consult the Siemens SINAMICS alarm manual for alarm 300721 complete remedy.

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Siemens SINUMERIK Controller

Program/G-code · Intermediate · 30-120 minutes

Alarm 300721

Siemens 840D 300721 - Axis drive zero-load current greater than rated motor current

This alarm occurs when the no-load current (MD 1136) is set higher than the rated motor current (MD 1103), indicating a configuration error in the motor parameters. Correct the values in the machine data to resolve it.

Siemens SINUMERIKProgram/G-codeIntermediate30-120 minutes

300721

Siemens 840D 300721 - Axis drive zero-load current greater than rated motor current

Axis drive zero-load current greater than rated motor current

Root Cause Summary

This alarm occurs when the no-load current (MD 1136) is set higher than the rated motor current (MD 1103), indicating a configuration error in the motor parameters. Correct the values in the machine data to resolve it.

Safety

Refer to Siemens documentation
Ensure qualified technician performs repairs

Causes and Fixes

1
Access machine data
Navigate to the machine data parameters via the control panel or configuration software.
2
Verify values
Check MD 1136 (no-load current) and MD 1103 (rated current). Ensure MD 1136 is less than or equal to MD 1103.
3
Correct and save
Adjust the values as needed, save changes, and reset the control to apply settings.

DIY Feasiblehigh confidence

Call a technician if:

·If access to machine data is restricted or unclear
·If the alarm persists after correcting the values

Prevention

Double-check motor data during setup or replacement
Use manufacturer-provided configuration tools for accuracy
Always follow lockout/tagout procedures when working on motor systems
Verify motor compatibility before installation

Common Mistakes

Entering values without verifying motor specs
Overlooking parameter dependencies in machine data

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Always verify with your machine manual or a certified technician before performing service procedures.