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ErrorLib — Industrial Fault Code Library

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Triplock

Triplock

Danfoss · VLT 2800 Variable Speed Drive

What does Triplock mean?

This alarm indicates that the drive has entered a Trip-Locked state, meaning it cannot be reset by simply pressing the [STOP/RESET] key. This usually occurs after a severe fault to ensure safety and require manual intervention.

Common Causes

  • A critical internal hardware fault (e.g., short-circuit on output, DC bus overvoltage/undervoltage, IGBT failure) that requires manual investigation.
  • Repeated occurrences of a specific fault (e.g., motor overload, ground fault) within a short period, indicating a persistent problem.
  • Safety circuit activation (e.g., STO input) in a way that requires explicit re-enablement rather than a simple reset.
  • Firmware or configuration corruption that prevents the drive from initializing correctly after a fault.
  • External fault input (e.g., Fbk, digital input configured for external trip) remaining active after the primary fault condition has cleared.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Record the specific fault code that led to the Triplock state (often displayed alongside or prior to Triplock).

  2. 2

    Completely remove all AC input power to the drive. Wait for the DC bus voltage to discharge to a safe level (typically <50VDC) using a multimeter.

  3. 3

    Restore AC input power to the drive. This power cycle typically clears a Triplock state if the underlying fault has been resolved and is not persistent.

  4. 4

    If the Triplock persists, access the drive's internal fault history log via the keypad or communication software to identify the root cause fault.

  5. 5

    Check all safety chain inputs (e.g., STO terminals) to ensure they are de-energized and then re-energized correctly according to the safety circuit design.

  6. 6

    If the previous steps fail, contact technical support for potential advanced diagnostics, firmware re-initialization, or hardware replacement procedures.

Browse all codes in this manual (40)
Verified technical data. Last updated: April 2026

Related Faults

10Motor overloaded11Motor thermistor12Current limit
Source: Danfoss VLT 2800 Variable Speed Drive
View Official PDFSearch more codes in this manual