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ErrorLib — Industrial Fault Code Library

Disclaimer: ErrorLib is an independent technical reference tool. While we aim for accuracy, always verify with the manufacturer’s official service manuals before performing maintenance on industrial equipment. ErrorLib is not affiliated with the brands listed.

9

Undervoltage

Vacon · NXP/C

What does 9 mean?

The DC-link voltage has fallen below the voltage limits defined in Table 37. This is most likely caused by a low or interrupted supply voltage. Subcodes in T.14 (S1, S2, S3) can indicate if the DC-link was too low during run, no data was received from the power unit, or undervoltage control supervision tripped. A persistent undervoltage condition can prevent the drive from operating or restarting.

Common Causes

  • Input voltage below minimum threshold (e.g., P1-01 < P1-02).
  • Loss of one or more input phases.
  • Faulty main power supply unit.
  • Brownout condition affecting the DC bus voltage.
  • Incorrect voltage setting for the operating environment.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    If the fault occurred due to a temporary supply voltage break, reset the fault and restart the frequency converter.

  2. 2

    Measure the incoming AC supply voltage at the frequency converter's input terminals and verify it is stable and within the specified operating range (e.g., 380-480VAC for a 400V class drive).

  3. 3

    If the supply voltage is confirmed adequate, an internal failure has likely occurred. Contact your local distributor.

Browse all codes in this manual (11)
Verified technical data. Last updated: April 2026

Related Faults

10Input line supervision11Output phase supervision12Brake chopper supervision
Source: Vacon NXP/C
Open Manual (Page 107)Search more codes in this manual