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ErrorLib — Industrial Fault Code Library

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SP9051

LOW VOLT POWER CIRCUIT

Fanuc · Series 0i-D/0i Mate-D Maintenance

What does SP9051 mean?

This Fanuc Series 0i-D/0i Mate-D spindle alarm indicates that an input voltage drop was detected in the power circuit (Power Supply (PS) alarm indication: 4). This typically signifies a momentary power failure or poor contact in the magnetic contactor (MC).

Common Causes

  • Input power supply voltage drop or sag affecting the spindle amplifier/PS unit.
  • Momentary power failure or interruption of the AC supply.
  • Poor contact, wear, or failure in the main magnetic contactor (MC) supplying power.
  • Loose or corroded power wiring connections to the spindle amplifier or PS unit.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Measure the incoming three-phase AC power supply voltage to the spindle amplifier (or PS unit) to confirm it is stable and within specifications.

  2. 2

    Inspect the main magnetic contactor (MC) for signs of wear, pitting, or poor contact; check its coil operation and auxiliary contacts.

  3. 3

    Check all power wiring connections from the main supply breaker through to the spindle amplifier for looseness or corrosion.

  4. 4

    Monitor the power supply for momentary voltage sags or interruptions, especially during machine operation or startup.

  5. 5

    If the magnetic contactor shows signs of failure or malfunction, replace it with an equivalent unit.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

361ABNORMAL PHASE DATA(INT)364SOFT PHASE ALARM(INT)365BROKEN LED(INT)
Source: Fanuc Series 0i-D/0i Mate-D Maintenance
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