SV0400 Servo Overload (Generic) fault in Fanuc drive

SV0400 Servo Overload (Generic) fault in Fanuc drive

Description

SV0400 is the "Generic" overload alarm, often seen on older Fanuc systems (System 0, 16, 18) or Beta series drives. It is less specific than the modern OVC (SV0436) or OHC (SV0430). It generally means the total load on the axis has exceeded the drive's capacity for a sustained period. It is a calculated thermal value based on current draw over time.

Cause

• Dull Tooling: The most common operator-induced cause. Pushing a dull drill requires excessive Z-axis thrust.
• Lubrication Failure: The automatic oiler is empty, and the ways are dry, doubling the friction coefficient.
• High Duty Cycle: Rapid-fire pecking cycles that don't allow the motor time to cool between moves.
• Voltage Sag: Low input voltage forces the motor to draw higher amperage to maintain the same power output.

Solution

1. Check Ways: Manually lube the ways. If the alarm clears, fix the lube pump.
2. Reduce Feedrate: Slow down the cutting cycle. If the alarm stops, it is a load issue, not an electrical one.
3. Check Motor Temp: Is the motor hot? If it is cold, the parameters for overload protection might be too conservative.