36

Mains failure

Danfoss · VLT AutomationDrive FC 301/302

What does 36 mean?

This warning/alarm is active when the supply voltage to the drive is lost. It is only issued if parameter 14-10 Mains Failure is not configured to [0] No function.

Common Causes

  • Momentary or sustained loss of one or more phases of the incoming AC supply voltage to the drive (e.g., L1, L2, L3).
  • Tripped upstream circuit breaker or blown fuses in the main distribution panel feeding the drive.
  • Loose or corroded connections at the drive's input power terminals (e.g., L1, L2, L3) causing intermittent contact.
  • Parameter P14-10 (Mains Failure) configured for a sensitive trip threshold (e.g., [1] Warning) leading to nuisance trips.
  • External contactor or switch upstream of the drive opening unexpectedly due to control circuit fault.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    1. Verify the status of the upstream circuit breaker (e.g., QF1) and fuses in the main power distribution panel.

  2. 2

    2. Measure the incoming AC line-to-line voltages (L1-L2, L2-L3, L3-L1) at the drive's input terminals to confirm stable three-phase supply (e.g., 400VAC ±10%).

  3. 3

    3. Inspect and tighten all power connections at the drive's L1, L2, L3 input terminals using a torque wrench to specified values (e.g., 5 Nm).

  4. 4

    4. Check the setting of parameter P14-10 (Mains Failure) on the drive's LCP; if it's set too sensitively, consider adjusting it to [2] Alarm if appropriate for the application.

  5. 5

    5. Examine the operation of any upstream main contactor (e.g., KM1) and its control circuit for proper engagement and coil voltage (e.g., 110VAC or 24VDC).

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Verified technical data. Last updated: March 2026

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Source: Danfoss VLT AutomationDrive FC 301/302