40

Calibration Constant Error (EEPROM)

Danfoss · VLT 2800 Variable Speed Drive

What does 40 mean?

An error has been detected in the calibration constants stored in the EEPROM. These constants are vital for accurate measurement and control, and any discrepancy can lead to incorrect drive outputs, poor motor control, or misinterpretation of sensor data. This suggests data corruption or a hardware issue with the EEPROM.

Common Causes

  • Corruption of critical calibration constants in EEPROM, potentially from power fluctuations or an incomplete save operation.
  • Manual incorrect entry or modification of system calibration parameters (e.g. voltage offsets, current scaling factors P7-XX).
  • Malfunctioning sensor or measurement circuit (e.g., current transducers, voltage sensors) feeding incorrect values, leading to erroneous stored constants.
  • Aging or faulty EEPROM chip unable to retain stable data values over time, causing discrepancies in stored constants.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    1. Re-perform the drive's specific calibration procedure for current, voltage, or feedback (e.g. Parameter P7-10 = 1 for auto-calibration).

  2. 2

    2. Verify the accuracy of external measurement devices (e.g., current transformers, voltage sensors) connected to the drive's inputs.

  3. 3

    3. Measure the actual input voltage at the drive's L1, L2, L3 terminals and compare to the drive's measured value shown in diagnostics.

  4. 4

    4. If re-calibration fails, reset the drive to factory defaults (P1-00 = 1) and attempt recalibration.

  5. 5

    5. Replace the control card if calibration constant errors persist after multiple attempts and input verification.

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Verified technical data. Last updated: March 2026

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Source: Danfoss VLT 2800 Variable Speed Drive