Fanuc Alarm code 12

Alarm 12 on Fanuc spindle amplifier modules

Any Fanuc spindle amplifier that has an 12 alarm indicates excesssively large current flowed into the DC link of the main circuit (high current). In smaller amplifiers the main circuit detected an error such as excessive load, overcurrent.

Probably the most common fault on ALPHA series spindle amplifiers and/or motors. Caused by a multitude of potential issues both mechanical or electrical.

There are five potential causes of the alarm 12 appearing on the amplifier.

  1. Mechanical issues on the spindle i.e. binding or obstruction.
  2. Motor power line is faulty.
  3. The motor has mechanical or winding insulation failuire.
  4. SPM spindle power module is faulty.
  5. Parameters specific to the motor are set incorrectly.

CNC Tip: Watch out for dubious claims about what causes alarm 12. Sensor faults will normally alarm with 26, 27, 31, 71, 73 and so on. Not normally alarm 12. If the speed sensor signal error is apparent you will need to consult the troubleshooting action guide in the mainteance manual for the relevent series of amplifiers.

We can test most ALPHA and ai spindle amplifiers, and models of AC spindle motors at our location in Virginia. We also supply servo drives, motors and system axis cards.

We always recommend using the services of a trained CNC service engineer whom has the electronic and mechanical training, experience and knowledge to deal with the Fanuc side of your machine tool.

The alarms above cover ALPHA 6078, 6082, 6088, 6092, 6012, 6104 and ALPHA i series 6111, 6112, 6121, 6122, 6141, 6142, 6151, 6152 and later aiSP modules.