SV0607 Spindle Open Phase (Input) fault in Fanuc drive

SV0607 Spindle Open Phase (Input) fault in Fanuc drive

Description

SV0607 (often Spindle Alarm 07) indicates an Open Phase condition on the AC input power specifically detected by the Spindle Amplifier. While the PSM monitors the main bus, some Spindle amplifiers monitor the input waveform ripple. If one of the three phases (L1, L2, L3) is missing or significantly unbalanced, the DC bus ripple becomes excessive. The drive shuts down to prevent the capacitors from overheating due to the "single-phasing" ripple current.

Cause

• Blown Fuse: A building fuse or a fuse in the machine's disconnect switch has blown on one leg.
• Loose Wire: A loose screw terminal on the input to the machine or the input to the drive.
• Contactor Failure: The main magnetic contactor is not conducting on all three poles.
• Detection Circuit: Rarely, the phase detection circuit on the spindle drive PCB itself has failed.

Solution

1. Measure Voltage Under Load: Voltages often look fine (200V) when the machine is idle due to "phantom voltage." Measure the voltage across phases while trying to run the spindle. If one leg drops to 100V or 0V, you have a bad supply line.
2. Check Breakers: Reset the main breaker. Sometimes a breaker trips internally on one leg but the handle stays up.
3. Tighten Connections: Thermal cycling loosens screw terminals. Re-torque all incoming power connections.