9

Inverter overload

Danfoss · VLT 2800 Variable Speed Drive

What does 9 mean?

The electronic thermal protection for the inverter indicates that the drive is close to disconnecting due to prolonged high output current. The internal counter gives a warning at 98% and trips at 100%. The drive cannot be reset until the counter drops below 90%.

Common Causes

  • Mechanical overload on the motor and driven equipment (e.g., jammed conveyor, worn bearings), causing sustained high current draw.
  • Incorrect motor parameters (P1-20 to P1-25) entered into the drive, leading to inaccurate thermal modeling.
  • Drive is undersized for the application, consistently operating above its nominal rated current.
  • High ambient temperature around the drive, reducing its cooling efficiency and thermal capacity.
  • Output filter or reactor issues causing excessive current ripple or impedance.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    1. Measure the motor's actual operating current (A01-04) and compare it to the drive's rated output current and the motor nameplate FLA.

  2. 2

    2. Inspect the mechanical system (bearings, gears, alignment) for binding, excessive friction, or jams that increase motor load.

  3. 3

    3. Verify all motor nameplate data (kW, V, A, Hz, RPM) is accurately entered into drive parameters P1-20 to P1-25.

  4. 4

    4. Ensure adequate airflow and ambient temperature (within specified limits) around the drive's heatsink and cooling fans; clear any dust or obstructions.

  5. 5

    5. If the application has high starting torque or transient loads, consider increasing the drive's current limit parameter (P2-21) temporarily for testing, if within safe operating limits.

  6. 6

    6. Perform a motor no-load test to determine if the drive's output current (A01-04) is reasonable without mechanical load.

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Verified technical data. Last updated: March 2026

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Source: Danfoss VLT 2800 Variable Speed Drive