SRVO-046: OVC alarm (overcurrent RMS)
The running average (RMS) of motor current exceeded the protection limit - the servo system's thermal-protection math saying the motor is being worked toward damage.
What it means
The running average (RMS) of motor current exceeded the protection limit - the servo system's thermal-protection math saying the motor is being worked toward damage. Different from HCAL's instantaneous spike: OVC is sustained overwork. Power-cycle to clear.
Common causes
Ranked by what technicians most often find, most likely first.
- Overload - payload or duty beyond rating.
- Sustained very slow motion increasing effective friction (a FANUC-specific quirk worth knowing).
- External force loading the robot.
- Brake dragging - not fully releasing (including mis-set brake number on aux axes, aux brake fuse).
- Low supply voltage forcing higher current.
- Hardware: motor, amplifier, cabling.
How to fix it
- Confirm payload and duty are within the robot's rating and reduce them if they are over. This is the usual cause: the running average of motor current exceeded the protection limit because the robot is being worked too hard, not because a component failed.
- If the program runs long stretches of very slow motion, break it up with a faster move. FANUC notes that sustained creep-speed motion raises effective current.
- With the robot stopped and the cell clear, remove any external force loading the arm.
- If a taught position binds the arm, re-teach it in T1 low speed with the deadman held and the cell clear.
- Beyond those, a dragging brake, low supply voltage, or a motor, amplifier, or cable fault is a qualified-technician task. Work it per the maintenance manual with the controller de-energized and locked out, and with the gravity-loaded axis blocked or supported before any brake or motor is touched, because a released brake lets the axis fall.
- Power-cycle to clear.