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ErrorLib — Industrial Fault Code Library

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08

Regeneration Excess Alarm

Fanuc · Alpha i Series AC Servo Motor and Spindle

What does 08 mean?

This alarm may be generated in the αi PSR when the spindle decelerates, particularly if a regenerative discharge unit with a resistance of 16Ω is used with a spindle motor having a maximum output of 5 kW or more. This indicates that the unit is not effectively dissipating regenerative energy.

Common Causes

  • Excessive regenerative energy during deceleration exceeds system limits.
  • Regenerative braking torque too high for controller's capacity.
  • Parameter settings for regeneration threshold (e.g., P3-01) are too low.
  • Faulty regenerative braking resistor system unable to dissipate excess energy.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Verify the maximum output of the spindle motor. If it is 5 kW or more, proceed to the next step.

  2. 2

    Check the resistance of the installed regenerative discharge unit. If it is 16Ω, replace it with an 8Ω regenerative discharge unit.

Browse all codes in this manual (29)
Verified technical data. Last updated: April 2026

Related Faults

1Over-current at Power Running (ECM)2Over-current at Regeneration (ECM)3Over-current of Charge Current (ECM)
Source: Fanuc Alpha i Series AC Servo Motor and Spindle
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