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ErrorLib — Industrial Fault Code Library

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U15

15V supply interfered

Lenze · 4800/4900 Series

What does U15 mean?

This fault indicates an issue with the drive's internal 15V power supply, which typically powers internal control circuitry, sensors, or external devices. By default, this critical condition triggers a full TRIP, inhibiting all ignition pulses and resetting the Ready signal, as instability in this supply can compromise the drive's internal operations and safety functions. Manual reset is required.

Common Causes

  • Overcurrent draw on the drive's internal 15VDC supply due to an external device connected to it (e.g., sensor, HMI).
  • Internal short circuit or component failure within the drive's 15VDC power supply circuit.
  • Loose connection or short in the wiring of any device powered by the drive's 15VDC output.
  • Electromagnetic interference (EMI) disrupting the regulation of the 15VDC supply.
  • Aging capacitors or failed voltage regulator component within the drive's control board.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Power off the drive and disconnect all external devices powered by the drive's 15VDC output terminals (e.g., X3).

  2. 2

    Power on the drive; if the fault clears, reconnect devices one by one to identify the faulty component.

  3. 3

    Measure the 15VDC output voltage at the drive's designated terminals (e.g., X3/pin 1-2) with no load connected.

  4. 4

    Using a multimeter, check for continuity or short circuits on the wiring of any device previously connected to the 15VDC supply.

  5. 5

    Inspect the drive's internal components (if safely accessible) for signs of overheating or bulging capacitors near the power supply section.

Browse all codes in this manual (31)
Verified technical data. Last updated: April 2026

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Source: Lenze 4800/4900 Series
View Official PDFSearch more codes in this manual