Siemens SINUMERIK codes
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Siemens SINUMERIK Controller

Servo/Axis · Intermediate · 30-120 minutes

Alarm 300758

Siemens 300758 - Axis drive generator mode: response voltage > switch-off

This alarm occurs when the sum of response voltage and hysteresis exceeds the deactivation threshold for generator mode in the drive configuration. Correct the machine data parameters to resolve it.

Siemens SINUMERIKServo/AxisIntermediate30-120 minutes

300758

Siemens 300758 - Axis drive generator mode: response voltage > switch-off

Axis drive generator mode: response voltage > switch-off

The sum of the values in MD1631: $MD_LINK_VOLTAGE_GEN_ON (response voltage for generator axis) + MD1632: $MD_LINK_VOLTAGE_GEN_HYST (voltage range for generator control) is greater than MD1633: $MD_LINK_VOLTAGE_GEN_OFF (deactivation threshold for generator axis) Control reaction: NC not ready. The NC switches to follow-up mode. Channel not ready. NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm. Channel not ready.

Root Cause Summary

This alarm occurs when the sum of response voltage and hysteresis exceeds the deactivation threshold for generator mode in the drive configuration. Correct the machine data parameters to resolve it.

Safety

  • Drive/power/encoder circuit: hazardous voltages may remain in the DC link after power-off. Lock out / tag out, wait for discharge per the drive documentation, and use qualified personnel only.

Causes and Fixes

  1. 1

    SAFETY: Lock Out/Tag Out

    Follow LOTO procedures before any inspection. Ensure all energy sources are isolated.

  2. 2

    Check Drive Parameters

    Verify MD1631 (generator on voltage), MD1632 (hysteresis), and MD1633 (generator off voltage) relationships. MD1631 + MD1632 must be < MD1633.

  3. 3

    Inspect Braking Resistor

    Check braking resistor condition, connections, and resistance values. Replace if damaged or out of specification.

  4. 4

    Review Motion Profile

    Reduce deceleration rates in CNC program to minimize regenerative energy.

Service Recommendedmedium confidence

Call a technician if:

  • ·Always for first occurrence - requires proper diagnosis
  • ·If braking resistor inspection reveals damage
  • ·If parameter adjustments don't resolve the issue
  • ·If unfamiliar with high-voltage safety procedures

Prevention

  • Verify machine data settings before running programs
  • Document correct parameter values for generator mode

Common Mistakes

  • Overlooking the specific machine data values mentioned in the alarm
  • Incorrectly adjusting unrelated parameters

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