SV0431 Converter: Overload (PSM) fault in Fanuc drive

SV0431 Converter: Overload (PSM) fault in Fanuc drive

Description

SV0431 indicates a thermal overload specifically in the Power Supply Module (PSM). It is different from SV0430 (Motor Overheat). This alarm means the main heat sink of the PSM, or the regenerative discharge resistor, has become too hot. The PSM supplies power to all axes and the spindle. If the total power draw of the machine exceeds the PSM's rating, or if the cooling system is blocked, this alarm shuts down the machine to prevent the power transistors from melting.

Cause

• Cooling Fan Failure: The large fan on the back of the PSM is dead.
• Blocked Heatsink: The cooling fins are completely clogged with oily shop dust.
• Aggressive Cycle: The machine is performing too many rapid accelerations/decelerations per minute, overheating the regen resistor.
• Cabinet Temp: The electrical cabinet A/C is broken, and the ambient temp is >50°C.

Solution

1. Inspect Fan: Check the fan on the back/top of the PSM unit. Replace if it is moving slowly.
2. Clean Fins: Blow compressed air through the unit from top to bottom.
3. Regen Resistor: If using an external regen resistor, check if it is glowing red hot. You may need a larger wattage resistor if the cycle time is very fast.