When a Schneider Altivar drive trips, it shows a three-letter code such as OCF or OLF and stops the motor. This guide covers the Altivar fault codes a maintenance team meets most often, what each one means, the usual cause, and how to clear it, so you can get from a stopped line to a root cause in minutes. The core mnemonics below are shared by the common Altivar ranges (ATV12, ATV32, ATV320, ATV340, ATV610, ATV630 and ATV930), but subcodes and names differ by range, so confirm the exact code in your model's programming manual.
Key takeaways
The Altivar protects itself and the motor by tripping the instant a measured value leaves its safe window: output current, DC bus voltage, heatsink temperature, or a lost signal. The keypad shows the three-letter code, the drive coasts the motor to a stop, and most faults latch until you reset them. The code is a pointer, not a verdict. OBF DC bus overvoltage does not mean the drive is broken; it means a high-inertia load was decelerated faster than the drive could bleed off the energy the motor pushed back.
The faults most common on the shop floor, with the code as it appears on the keypad, the meaning, and the usual cause. The complete list for your exact model is in its programming manual.
| Code | Fault | Usual cause |
|---|---|---|
| OCF | Overcurrent | Output current exceeded the limit (ramp too short, mechanical jam, undersized drive) |
| OBF | DC bus overvoltage | Deceleration too fast for a high-inertia load, or braking energy with nowhere to go |
| OSF | Mains overvoltage | Incoming line voltage above the drive rating |
| USF | Undervoltage | Supply voltage dropped below the minimum |
| PHF | Input phase loss | A missing or unbalanced incoming supply phase |
| OPF1 / OPF2 | Output phase loss | One or all motor phases lost between drive and motor |
| OLF | Motor overload | The motor drew more current than its thermal setting allows, for too long |
| OHF | Drive overheat | Heatsink too hot: blocked cooling, failed fan, high ambient |
| SCF1 to SCF5 | Short circuit | Output short, IGBT short, or a motor-to-ground short |
| SOF | Overspeed | Motor speed exceeded the set maximum |
| CrF | Precharge fault | DC bus charging relay or precharge resistor problem |
| LFF1, LFF3 (by input) | 4-20 mA loss | A configured 4-20 mA analog input lost its signal. The digit is the input: LFF3 is AI3 on an ATV320, LFF1 is AI1 on an ATV12. |
| tnF | Autotune fault | Motor autotuning could not complete (wrong data or wiring) |
| EEF1 / EEF2 | EEPROM fault | A memory fault on the control or power board |
| SLF1 to SLF3 | Communication loss | SLF1 is the Modbus link, SLF2 the PC software link, SLF3 the remote keypad link |
| InF | Internal fault | An internal drive fault, with a suffix identifying the subsystem |
OCF Overcurrent. The output current spiked past the limit. Look at the mechanics and the ramp first: a jam, a seized bearing, or a load that grew, then an acceleration ramp that is too short for the inertia. Rule out a motor cable fault and confirm the drive is sized for the motor before you suspect the hardware.
OBF DC bus overvoltage. On a real line this is almost always a deceleration problem: a loaded conveyor or a high-inertia fan is stopped faster than the drive can absorb the energy the motor returns. Extend the deceleration time, or fit a dynamic braking resistor sized for the load. This is the same physics behind a VFD overvoltage fault on any brand.
OSF and USF, supply voltage. OSF means the incoming line is too high; USF means it sagged too low. Both are upstream of the drive. Measure the actual supply under load, check for a loose incoming terminal, and look for a large motor or welder on the same feed that pulls the line down on start.
OLF Motor overload. The motor pulled more current than its thermal model allows. Check the mechanical load, then confirm the motor thermal current parameter matches the motor nameplate. A recurring OLF on the same machine is a load or a motor problem, not a nuisance to be raised away.
OHF Drive overheat. The heatsink ran too hot. Clean the heatsink, check the cooling fan and the enclosure ventilation, and confirm the ambient temperature. A drive in a sealed panel next to a heat source will trip on a hot afternoon even when nothing electrical is wrong.
Before any hands-on check on the drive output or the motor: isolate the drive and lock out its supply, including any external control power, then wait 15 minutes for the DC bus capacitors to discharge and confirm with a meter that the DC bus reads below 42 V DC.
SCF short circuit and OPF phase loss. SCF is a genuine electrical fault: with the drive locked out and the DC bus verified below 42 V DC, disconnect the motor cable at the drive output and megger the motor and the cable from there, never through the drive, and inspect the terminations before running again. OPF1 or OPF2 means a motor phase is missing: check the drive-to-motor wiring, the terminals, and any output contactor.
Do not clear a fault until you know why it tripped. Once the cause is fixed, most Altivar faults reset by cycling input power, by a configured digital-input fault reset, over the fieldbus, or with the STOP/RESET key on the graphic display terminal when the keypad is the active command channel. Some, such as CrF1 precharge, the EEF1 and EEF2 EEPROM faults and the InF internal faults, clear only with a full power cycle: switch off until the display goes completely dark, then back on. SCF1 and SCF3 clear by themselves the moment the short disappears, so a cleared SCF is not proof that the insulation is healthy. If the code returns the instant you run, the condition is still present. Repeatedly clearing an OCF or an SCF just to keep production moving is how a small problem becomes a burned motor or a damaged drive.
One overload trip is an event. The same Altivar tripping on OLF every shift, or on OHF every summer afternoon, is a pattern that predicts a failure. Teams that stay ahead of drive faults do not just reset them, they log them: which code, which asset, which shift, how often. That record is where a stopped machine becomes a scheduled fix instead of a surprise.
This is what a CMMS and predictive maintenance software are for: capturing every trip against the asset, surfacing the drives that fault most, and planning a follow-up task before the next one stops the line. If drive faults are turning into unplanned downtime, book a demo and we will show you how the recurring ones get caught early.
Related reading: VFD overcurrent fault troubleshooting, motor overload relay tripping, and fault-code guides for other drives: ABB, Siemens Sinamics and Yaskawa.
SCF is not one fault but a family, and the digit tells you where to look. On an ATV320, SCF1 is a motor short circuit, SCF3 is a ground short circuit, SCF4 is an IGBT short circuit inside the drive, and SCF5 is a motor or load short circuit detected during the drive's load sequence. SCF1 and SCF3 clear by themselves as soon as the short disappears, so an intermittent insulation fault can look like a one-off trip. SCF4 and SCF5 stay latched until a fault reset, an automatic restart or a power cycle.
To tell a drive fault from a motor or cable fault, isolate and lock out the drive, wait 15 minutes and confirm with a meter that the DC bus is below 42 V DC. Then disconnect the motor leads at the drive output terminals.
An SCF1 on a motor and cable that pass the insulation test is usually not a real short. Schneider lists a saturated motor drawing high magnetizing current, a motor with low inductance, an unsymmetrical motor circuit, and cabling problems as causes. Check that the magnetizing current the drive measures is reasonable for the motor, try a different motor control law or switching frequency (SFr), and fit a motor choke to smooth the current ripple. Where several motors run in parallel from one drive, their combined leakage current to ground can also trip SCF, and motor chokes are Schneider's remedy there too.
What is the most common Altivar fault? On most lines it is OCF overcurrent or OLF motor overload, both usually a load or ramp problem, followed by OHF drive overheat in hot weather and OBF DC bus overvoltage on hard-stopping machines.
How do I reset an Altivar fault? Fix the cause first, then reset by cycling input power, by a configured fault-reset input, or over the fieldbus. Faults such as CrF1, EEF1, EEF2 and InF need a full power cycle, with the display completely dark, before they clear. SCF1 and SCF3 clear on their own once the short is gone, so test the insulation anyway.
What does OBF mean on an Altivar? OBF is a DC bus overvoltage, almost always from decelerating a high-inertia load too fast. Extend the decel time or fit a braking resistor rated for the load.
Does a fault code mean the Altivar is broken? Usually not. Most Altivar codes point to the supply, the load, the motor cable, or the cooling. A true internal drive fault such as InF is the exception, not the rule.
Fabrico is a manufacturing operations platform combining OEE monitoring with computer vision, a full CMMS, MES capabilities and PLC connectivity in one data model.
Stop chasing this fault by hand. Fabrico logs each stop against the machine's history, so a repeating fault shows up before it becomes a hard line stop, and the team can open a prioritized work order with the stop itself captured on video wherever a camera covers the line.
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