Cooling fan
Common VFD, drive, UPS, and cabinet overheating failure point.
Schneider ATV71 Fault Codes - What They Mean
The Schneider Electric Altivar 71 is a variable frequency drive used on pumps, fans, conveyors, compressors, and process machinery. ATV71 faults usually point to one of five areas: incoming power, motor wiring, load condition, braking/deceleration setup, or cabinet cooling.
Common ATV71 Fault Codes
| Code | Meaning | First Check |
|---|---|---|
| OCF | Overcurrent | Motor leads, shorted cable, jammed load |
| ObF | Overbraking or DC bus overvoltage | Decel ramp, braking resistor, regen load |
| OHF | Drive overheating | Fan, heatsink, cabinet temperature |
| OLF | Motor overload | Motor current, load, motor nameplate setup |
| PHF | Input phase loss | Supply fuses, contactor, L1/L2/L3 balance |
| OPF1 / OPF2 | Output phase loss | Motor terminals and cable continuity |
| SCF1 / SCF3 / SCF4 | Motor short circuit or ground fault | Megger motor and cable separately |
| SOF | Overspeed | Encoder feedback, speed loop, load overhauling |
| USF | Undervoltage | Incoming line voltage under load |
| LFF | Loss of 4-20 mA signal | Analog input loop and transmitter power |
Step-by-Step Fix
- Record the exact code and state. Note whether the ATV71 faults at power-up, on run command, during acceleration, during deceleration, or after several minutes.
- Measure incoming power. Check all phase-to-phase voltages at L1, L2, and L3 under load. PHF and USF often come from a weak supply, blown fuse, or bad contactor pole.
- Isolate the motor circuit. For OCF or SCF faults, power down, wait for the DC bus to discharge, then test motor leads and insulation. A shorted motor cable can trip the drive before the motor turns.
- Check the load. A seized fan, pump, gearbox, or conveyor can create OCF or OLF even when the drive is healthy.
- Review ramps and braking. ObF usually means the machine is regenerating energy into the DC bus faster than the drive can absorb it. Lengthen decel time, verify ramp adaptation, and inspect the braking resistor circuit if installed.
- Inspect cooling. Clean the heatsink path, verify the drive fan, and check cabinet filters. OHF often returns after the cabinet door closes.
- Reset after the cause is fixed. Clear the fault from the keypad or control system, then run the same operating condition that caused the trip.
Parts Often Needed
| Part | Notes |
|---|---|
| Cooling fan kit | Common on older ATV71 cabinets with OHF |
| Braking resistor | Needed when ObF appears during aggressive deceleration |
| Input fuses | Replace only with the specified class and rating |
| Motor cable | Replace if insulation fails megger testing |
| Replacement ATV71 or retrofit drive | Consider when SCF or OCF persists with motor leads disconnected |
Need Replacement Parts?
Before ordering, match the drive part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
When to Call a Pro
Call a qualified drive technician if OCF, SCF, or OHF returns with the motor disconnected. That points to an internal power module, current sensor, or cooling fault inside the drive.
Source Notes
- Schneider Electric ATV71 Programming Manual, document 1755855.
- Schneider Electric FAQ FA175486 on ATV61 and ATV71 ObF overbraking faults.