Schneider Altivar Fault INF — Causes & Fix

What this code means

INF on a Schneider Electric Altivar drive (ATV312, ATV320, ATV630, ATV930 series) indicates an internal fault. The drive’s self-diagnostic system detected an internal error that it cannot attribute to an external cause — this may be a memory error, a communication fault between internal boards, or a hardware failure in the power or control stage. The drive stops and locks out. INF is a serious fault that typically requires more than a simple reset to resolve.

Common Causes

• EEPROM or memory error — Corrupted internal memory from a power interruption during a write operation or from EEPROM end-of-life.
• Communication error between control and power cards — On larger Altivar drives with separate control and power boards, a failure in the inter-board communication bus triggers INF.
• Power supply fault within the drive — An internal switched-mode power supply feeding the control electronics has failed or is producing out-of-spec voltage.
• Firmware fault or version mismatch — A firmware update that did not complete correctly, or a control card that does not match the firmware version expected by the drive.

Step-by-Step Fix

1. Power cycle the drive completely — Remove input power for at least 2 minutes (allow DC bus to fully discharge) and restore. Some INF faults caused by transient memory errors will clear on a full power cycle.
2. Attempt a factory reset — Access the drive menu and navigate to the Reset to factory defaults option (typically under Settings or Factory Reset). This re-initializes EEPROM. Note: this will clear all parameter changes; record parameters first if possible.
3. Check the fault history — Review the fault history log on the keypad. If INF appears alongside other faults (UV, OHF), the root cause may be power supply related.
4. Inspect internal connections — On larger Altivar models, open the drive cover and check the ribbon cable and harness connections between the control card and power stage. Re-seat any loose connectors.
5. Check the 24V internal power supply — On drives with accessible test points, verify the internal 24V DC supply is within specification. An out-of-spec supply will cause control card resets and INF faults.
6. Update or reinstall firmware — If the fault is firmware-related, use the Altivar DTM or SoMove software to reflash the drive firmware to the correct version.
7. Replace the control card — If the above steps do not clear INF, the control board has a hardware fault and must be replaced.

Parts Often Needed

When to Call a Pro

INF is rarely field-repairable beyond a factory reset. If power cycling and parameter initialization do not clear the fault, contact a Schneider Electric-authorized drive service center for control card replacement and firmware verification.