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Inside the PSM, PSMR, PSMi, AiPS, AiR and other Fanuc ALPHA and ai power supply modules the main circuit detects the DC voltage at the DC Link is abnormally high, hence producing Fanuc alarm 7.

Fanuc alarm code 7 illuminates on any of following series of power modules:

Causes and solutions to AL.7

  • Excessive regenerated power
    • The power supply module has blown up acting as a regenerative braking system when the spindle module is commanded to slow/stop the spindle motor.
  • AC power source is too high (Over Voltage).
    • If the incoming voltage supplied at maximum output is beyond 7% then check AC. Normal operating voltage is with +/-7% of the specified input dependent on 200VAC or 400VAC amplifiers series. Voltage is specified on each power supply module.
  • Three phase cut off due to Emergency stop.
    • If the machine had the emergency stop state released then all three phase is cut off to electrically isolate the machine.
  • No display (sign of life) on PSM or any connected amplifiers
    • Check the machine is switch on at the breaker.

NOTE: Alarm Code 7 can be accompanied by Alarm 11 on the SPM/aiSP. If so then the PSM will need replaced assuming all other electrical checks have taken place; then if the Spindle Alarm changes to 12 it blew up at the same time as the PSM and will need replaced.

Fanuc Parts Specialist:

If your Fanuc power supply module alarm 7; then we can help by assisting you with diagnosis and the supply of parts or repair of drivesmotors and control system boards.

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