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FANUC Robot Controller
Servo/Axis · Intermediate · 15-60 minutes
Fanuc Robot SRVO-046 - OVC alarm (overload)
SRVO-046 OVC alarm occurs when the RMS (Root Mean Square) current calculated over a moving time window exceeds the thermal protection threshold for the motor and amplifier combination. The servo amplifier monitors continuous current draw and triggers this alarm before thermal damage occurs to protect expensive hardware. This is distinct from instantaneous overcurrent faults and indicates sustained overload conditions.
SRVO-046
Fanuc Robot SRVO-046 - OVC alarm (overload)
OVC alarm (overload)
The RMS current on the specified axis has exceeded the maximum permissible value. The servo system has issued this alarm to protect the motor and amplifier from thermal damage.
Root Cause Summary
SRVO-046 OVC alarm occurs when the RMS (Root Mean Square) current calculated over a moving time window exceeds the thermal protection threshold for the motor and amplifier combination. The servo amplifier monitors continuous current draw and triggers this alarm before thermal damage occurs to protect expensive hardware. This is distinct from instantaneous overcurrent faults and indicates sustained overload conditions.
Safety
- Always verify robot is in a safe stopped state before entering the work envelope
- Use T1 (low speed) mode when testing after clearing motion or servo alarms
Causes and Fixes
- 1
Verify alarm axis and check for physical obstructions
Press RESET on teach pendant, then MENU > ALARM > F1 [HIST] to view alarm history. Note which axis number triggered SRVO-046. Manually jog the affected axis in both directions at 5% override (COORD > JOINT, set override to 5%). Listen and feel for grinding, catching, or unusual resistance throughout the entire range of motion.
Ensure all personnel are clear of robot work envelope before jogging. Use DEADMAN switch properly - half-pressed during motion.
- 2
Inspect mechanical path for interference
Visually inspect the affected axis for cable interference, hose bundle interference with framework, or collision damage. For J1-J3 axes, check for base obstructions or cable carrier binding. For J4-J6 wrist axes, verify tool mounting doesn't interfere with cable dress-out package. Check all mechanical hard stops and axis limit bumpers for damage.
Wrist axis overloads (J4/J5/J6) are often caused by improperly routed tool cables that bind during rotation. Check cable routing at full axis travel in both directions.
- 3
Check gearbox and bearing condition
With servo power OFF, manually move the affected axis by hand (motors will back-drive). Feel for smooth motion throughout entire range. Grinding or notchy feel indicates bearing or gearbox damage. For wrist axes, grasp the axis output flange and check for excessive play or radial looseness indicating bearing wear.
Ensure SERVO OFF before attempting to back-drive motors. Some axes may drop under gravity - support appropriately.
- 4
Review program for sudden motion or excessive acceleration
Examine the robot program at the point where alarm occurred. Check for CNT (continuous) values that are too aggressive, excessively high programmed speeds, or rapid direction changes under load. Review MENU > SETUP > PAYLOAD to confirm payload value matches actual tool weight. Incorrect payload settings cause motion planner to command excessive accelerations.
If alarm occurs at same program line repeatedly, temporarily reduce speed to 50% and increase CNT smoothing. If alarm disappears, motion profile is too aggressive for the load conditions.
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