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Siemens SINUMERIK Controller
Spindle · Intermediate · 30-90 minutes
Siemens 21615 - Axis taken from traverse mode to follow-up mode
SIEMENS alarm 21615 fires when the SINAMICS drive DC bus voltage drops below the threshold defined in MD36300 (motor module) or MD36200 (infeed module). This typically occurs due to incoming power supply issues, regenerative braking overload, or drive hardware faults affecting the rectifier or DC bus capacitors.
21615
Siemens 21615 - Axis taken from traverse mode to follow-up mode
Axis taken from traverse mode to follow-up mode
This axis has been taken from traverse mode and put into "Follow-up" mode, for instance because the pulse enable for the drive has been reset Control reaction: NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm.
Root Cause Summary
SIEMENS alarm 21615 fires when the SINAMICS drive DC bus voltage drops below the threshold defined in MD36300 (motor module) or MD36200 (infeed module). This typically occurs due to incoming power supply issues, regenerative braking overload, or drive hardware faults affecting the rectifier or DC bus capacitors.
Safety
- Only qualified personnel should diagnose and clear control alarms; follow the machine builder's safety procedures and lockout/tagout where hardware work is required.
Causes and Fixes
- 1
Check Line Voltage at Drive Input
Navigate to HMI > Diagnostics > Drive > Actual Values and verify input voltage L1-L2-L3. Compare against nameplate rating and MD32000 (nominal line voltage).
Use SINAMICS Startdrive to monitor real-time voltage values during alarm occurrence
- 2
Verify Power Supply Stability
Check facility power quality with oscilloscope at drive input terminals. Look for voltage sags, harmonics, or phase imbalance affecting rectifier operation.
Measure with drive powered - use proper PPE and lockout procedures
- 3
Review Drive Parameters
Access Parameter > Drive > Power Supply and verify MD32000 matches actual supply voltage. Check MD36200 (infeed undervoltage threshold) is appropriate for application.
MD36200 default is typically 85% of nominal DC bus voltage
Call a technician if:
- ·DC bus capacitor replacement required
- ·Rectifier module hardware failure confirmed
- ·Persistent alarms after parameter corrections
Prevention
- Monitor DC bus voltage trends via r0026
- Schedule preventive capacitor replacement every 5-7 years
- Maintain proper drive cooling and ambient temperature
- Use line reactors to improve power quality
Common Mistakes
- Ignoring power quality issues at facility level
- Incorrect MD36200/MD36300 threshold settings
- Operating with degraded cooling system
- Oversized braking resistor parameters causing nuisance trips
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