Servo Alarm ((exclusive)) Jun 2026

Many drives have a 7-segment display or digital readout. Some show a history log (e.g., Fanuc: press [>] to view previous alarms).

| Code Example | Common Name | Likely Cause | |--------------|----------------|----------------| | (Overcurrent) | Drive fault | Short circuit, bad motor winding, IGBT failure | | A.HF (Overvoltage) | DC bus too high | Regenerative energy, wrong braking resistor | | A.LV (Undervoltage) | Low DC bus | Poor mains supply, weak transformer | | A.OL (Overload) | Motor overload | Mechanical jam, wrong motor sizing | | A.OS (Overspeed) | Speed exceeded | Encoder loss, incorrect tuning | | A.ENC (Encoder error) | Feedback loss | Broken encoder cable, dirty connector | | A.POS (Position error) | Following error | Slipping coupling, excessive friction | | A.OH (Overtemp) | Drive/motor hot | Fan failure, high ambient temp | | A.CPU | Processor fault | Internal drive failure, firmware crash | servo alarm

: Servo motors and their controllers can overheat due to environmental conditions, prolonged operation at high speeds or under heavy load, or issues with the cooling system. Many drives have a 7-segment display or digital readout