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ErrorLib — Industrial Fault Code Library

Disclaimer: ErrorLib is an independent technical reference tool. While we aim for accuracy, always verify with the manufacturer’s official service manuals before performing maintenance on industrial equipment. ErrorLib is not affiliated with the brands listed.

InF

Internal Fault

Schneider Electric · ALTIVAR 28 Variable Speed Drive

What does InF mean?

This fault indicates an internal malfunction within the drive controller, potentially stemming from environmental electromagnetic interference or an improper connection/disconnection of the local control option while powered. Ignoring this can result in total drive failure and loss of control.

Common Causes

  • Excessive electromagnetic interference (EMI) disrupting internal drive logic (e.g., unshielded power cables near control wiring).
  • Improper connection or disconnection of control panel/HMI while drive is powered, corrupting configuration.
  • Transient voltage spike or sag on the control power supply (e.g., 24VDC) causing CPU instability.
  • Corrupted firmware or configuration data due to power interruption during write cycles.
  • Internal sensor fault (e.g., current, voltage, temperature sensor) providing erroneous data to the controller.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    1. Cycle drive power (turn off, wait 30 seconds, turn on) to clear transient conditions.

  2. 2

    2. Verify control wiring shielding is properly terminated at the drive ground terminal and not at both ends (ground loop).

  3. 3

    3. Measure incoming control power supply (e.g., 24VDC) stability with an oscilloscope for voltage dips or spikes.

  4. 4

    4. Perform a factory reset (e.g., Parameter P9-01 = 1) to clear corrupted configuration, then re-enter essential motor parameters.

  5. 5

    5. Check for loose internal connections by physically inspecting the drive's control board connections.

Browse all codes in this manual (13)
Verified technical data. Last updated: April 2026

Related Faults

EEFInternal FaultOCFOvercurrentOHFDrive Controller Overheat
Source: Schneider Electric ALTIVAR 28 Variable Speed Drive
View Official PDFSearch more codes in this manual