16

Short circuit

Danfoss · VLT AutomationDrive FC 301/302

What does 16 mean?

A short-circuit condition is detected either in the motor windings or within the motor wiring connecting to the frequency converter. This poses a significant risk of damage to the drive and motor if not resolved.

Common Causes

  • Phase-to-phase short-circuit within the motor windings.
  • Short-circuit between two or more motor output phases in the motor cable (e.g., U-V, V-W, U-W).
  • Mechanical damage to the motor cable causing direct contact between phase conductors.
  • Water ingress or severe contamination in the motor terminal box creating a conductive path between phases.
  • Internal fault within the drive's output stage (e.g., failed IGBT module, gate drive circuit failure).

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Power down the drive and disconnect the motor leads (U, V, W) from the drive's output terminals.

  2. 2

    Use a multimeter to measure the resistance between each pair of motor phases (U-V, V-W, W-U) for both the motor cable and motor windings. Look for resistance values close to zero Ohms.

  3. 3

    Inspect the entire length of the motor cable for severe physical damage, crushing, or cuts that could cause phase-to-phase contact.

  4. 4

    Open the motor terminal box and inspect for moisture, carbon tracking, or debris bridging terminals.

  5. 5

    If the motor and cable show no short-circuit, the fault likely lies within the drive's power section (e.g., IGBT module), requiring service.

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Verified technical data. Last updated: March 2026

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Source: Danfoss VLT AutomationDrive FC 301/302