SV0407 Excess Error (Torque Limit) fault in Fanuc drive

SV0407 Excess Error (Torque Limit) fault in Fanuc drive

Description

SV0407 is a variation of the common "Excess Error" (SV0411) alarm. However, SV0407 specifically tells you why the error happened: the motor hit its programmed Torque Limit. The CNC commanded a move, the motor tried to go, but the current required to make that move exceeded the value in parameter 2060 (or 2165). The drive capped the current to protect the machine, the motor slowed down, the position error grew, and SV0407 tripped.

Cause

• Physical Obstruction: The axis is pushing against a clamp, a pile of chips, or a dull tool.
• Low Limit Setting: The torque limit parameter is set too low (e.g., 50%) for the cutting operation being attempted.
• Counterbalance: On Z-axes, if the hydraulic counterbalance fails, the motor has to hold the full weight of the head, using up 80% of its torque just to stand still. Any movement hits the 100% cap.

Solution

1. Check Load Meter: View the servo load screen. If the axis sits at 90% load while stopped, you have a mechanical bind or counterbalance failure.
2. Check Limits: Verify the torque limit parameters (typically 2060 for T1, 2096 for T2). They are usually set to high values (150-200%). If set to 50%, increase them.
3. Tooling: Check for broken inserts or excessive depth of cut.