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Fanuc Alarm 12 Excessively Large Current

An excessively large current flowed into the DC link of the main circuit. Fanuc alarm 12 indicates that the power section of the drive has detected an error / fault such as excessive load, overcurrent, or low control supply voltage.

Fanuc alarm 12 indicates on the following series of drives.

Does the alarm happen when motor stopped.

  • If this alarm is issued immediately after a spindle rotation
    • The motor power line is faulty.
    • Check for a short circuit between motor power lines and short-circuit to ground, and replace the power line as required.
  • The motor winding has an insulation failure.
    • If the motor is short-circuited to ground, replace the motor.
  • The parameters specific to the motor are not set correctly.
  • The AC Spindle Unit, SPM, aiSP is faulty.

If this alarm is issued during spindle rotation

  • A power element is destroyed.
    • A power element (IGBT, IPM) may be destroyed. Replace the SPM.
    • If the amplifier setting condition is not satisfied, or cooling is insufficient because the heat sink is dirty, the power elements may be destroyed.
    • When the heat sink on the back of the amplifier is too dirty, clean the heat sink, for example, by blowing air. Consider the use of a structure that prevents the heat sink from being directly exposed to coolant.
  • The parameters specific to the motor are not set correctly.
    • Refer to parameter manual relevant to Spindle amplifier series
  • Speed sensor signal error
    • Check the spindle sensor signal waveform

Fanuc Parts Specialist:

If your Fanuc spindle drive alarm 12; then we can help by assisting you with diagnosis and the supply of parts or repair of drivesmotors and control system boards. Further we can build cables on order if required.

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