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FANUC Controller
Servo/Axis · Advanced · 1-3 hours
Fanuc Alarm 432 - Inverter Current Overload
Fanuc Alarm 432 indicates the DC control voltage in the servo amplifier (PSM, PSMR, or beta SVU) has dropped below the acceptable threshold. This is typically caused by incoming AC power issues, blown control circuit fuses (FU01/FU02 on PSM units), or faulty power supply module components affecting the +24VDC control bus.
432
Fanuc Alarm 432 - Inverter Current Overload
INV Current Overload
Motor or drive overload condition. The inv current overload has exceeded its rated current capacity and may be at risk of thermal damage.
Root Cause Summary
Fanuc Alarm 432 indicates the DC control voltage in the servo amplifier (PSM, PSMR, or beta SVU) has dropped below the acceptable threshold. This is typically caused by incoming AC power issues, blown control circuit fuses (FU01/FU02 on PSM units), or faulty power supply module components affecting the +24VDC control bus.
Safety
- Disconnect motor before testing
- High voltage present
Causes and Fixes
- 1
Verify incoming AC voltage at the PSM input terminals (L1, L2, L3). Should be within 200-230VAC ±10% for single-phase or 200-230VAC 3-phase depending on PSM model. Check for voltage sags or imbalance.
HIGH VOLTAGE - Use proper PPE and lockout/tagout procedures
- 2
Navigate to SYSTEM > DIAGNOSIS > #0390-#0391 (PSM monitor) or check PSM amplifier LED indicators. On alpha/beta SVU, LED will show fault code pattern (rapid flashing indicates DC link or control voltage fault).
- 3
Measure DC control voltage at PSM/PSMR output: +24VDC control bus should read 24VDC ±5%. Check X7 connector terminals on PSM or control voltage distribution points on servo amplifier rack.
- 4
Inspect and test control circuit fuses FU01 and FU02 (typically 4A or 5A depending on PSM model) located on PSM front panel. Replace if blown and investigate cause before re-energizing.
Call a technician if:
- ·Amplifier hardware failure confirmed
- ·Motor winding failure detected
- ·Multiple axes affected simultaneously
- ·Alarm persists after mechanical issues resolved
Prevention
- Regular lubrication of mechanical components
- Periodic inspection of motor cables
- Avoid exceeding programmed feedrates and spindle loads
- Monitor servo current levels during operation
Common Mistakes
- Ignoring mechanical binding and only focusing on electrical causes
- Setting current limits too high to mask underlying problems
- Swapping components without proper documentation
- Not checking motor cable connections before replacing expensive components
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