When a Schneider Electric Altivar drive trips and the keypad shows a code like OCF, SCF1 or ObF, knowing what the code means — and whether it points at the motor, the supply, or the drive itself — is the fastest route back to production. This guide explains how Altivar fault codes work, decodes the ones you will see most often, and shows when a fault means the drive needs replacing.
Altivar is the variable-frequency drive line from Schneider Electric — historically sold under the Telemecanique brand. The codes below are broadly consistent across the popular ranges (ATV12, ATV32, ATV61, ATV71, ATV320, ATV630/ATV930), with small differences by model and firmware.
How Altivar fault codes work
When the drive detects a condition it cannot run through, it stops the motor, shows a three-letter code on the display, and writes the event to its fault history. Each fault falls into one of three reset categories — which is the first thing worth knowing, because it tells you how much trouble you are in:
-
Auto-clearing — the fault clears by itself once the cause is gone (for example
USF,PHF). -
Manual or automatic reset — clearable via the reset input or auto-restart once the cause has disappeared (for example
OHF,OLF). -
Power reset required — the drive must be fully powered down before it will run again (for example
OCF,SCF).
The most common Altivar fault codes
| Code | Meaning | Likely cause | Check first |
|---|---|---|---|
OCF |
Overcurrent | Acceleration ramp too short; inertia or load too high; mechanical jam; wrong motor/drive sizing or parameters | Review the accel ramp and motor data; check the mechanism. Power reset required |
SCF1 |
Motor short circuit | Phase-to-phase or winding short; damaged cable insulation | Megger the motor and cable; check terminals. Power reset required |
SCF3 / SCF4 / SCF5 |
Ground / IGBT / motor short variants | Earth fault; failed output IGBT; motor short | Megger to ground; a confirmed IGBT short usually means a damaged power stage |
OHF |
Drive overheat | Ambient too hot; blocked ventilation; failed fan; sustained overload | Check cooling, fans and load; let it cool — resettable once the cause is gone |
OLF |
Motor overload | Motor drawing excess current too long; undersized motor or jammed load | Check the load and motor thermal settings; resettable after cooling |
ObF |
DC bus overvoltage (overbraking) | Deceleration too fast; regenerated energy with no braking resistor | Extend the decel ramp; fit or check a braking resistor |
OSF |
Supply mains overvoltage | Line voltage too high | Check the incoming supply — auto-clears when back in range |
USF |
Supply mains undervoltage | Line voltage too low, or a dip/loss | Check supply and connections — auto-clears when restored |
PHF |
Input phase loss | Missing input phase; blown fuse; loose terminal | Check input fuses and all three phases — auto-clears |
OPF1 / OPF2 |
Output phase loss | Broken motor cable; loose motor terminal; open winding | Check the motor cable and terminals |
SLF1 / SLF2 / SLF3 |
Serial / Modbus communication fault | Lost or noisy comms link; controller stopped; wrong settings | Check the comms cable, address and baud rate; confirm the controller is running |
CnF |
CANopen communication fault | Bus fault; missing node; wiring | Check CANopen wiring and node configuration |
EPF1 / EPF2 |
External fault | A wired or fieldbus external-fault signal was triggered | Check the source device wired to the external-fault input |
tnF |
Autotuning fault | Motor not connected or too small for the drive; tuning conditions not met | Verify motor wiring and data; re-run autotune |
CFF |
Incorrect configuration | Option module changed; configuration conflict | Restore a valid configuration or factory settings |
InF |
Internal fault | Internal hardware fault; EMC; component damage | Power reset; if it recurs, the drive likely needs repair or replacement |
Reset behaviour: why some faults clear and others don’t
The reset category is a useful triage tool. Auto-clearing faults like USF and PHF are almost always supply-side — fix the power and they vanish. Faults that allow manual or automatic reset (OHF, OLF) are usually thermal or load related and clear once the drive cools or the load is corrected. A fault that demands a full power reset (OCF, SCF) is the drive protecting itself from a serious electrical event — never just keep cycling power without finding the cause, or you risk turning a recoverable trip into a destroyed power stage.
When an Altivar fault means the drive needs replacing
Most Altivar faults are wiring, parameter, supply or load issues you can resolve on site. A few point at failed hardware:
- A confirmed
SCFcaused by a shorted output IGBT (not a motor or cable short) means the power stage is damaged. - Repeated
InFinternal faults after a clean power reset and EMC check usually indicate a failing control or power board. - An
OCFthat returns instantly on a known-good motor and load, with correct parameters, points at the drive itself.
On older or discontinued Altivar units (ATV31, ATV58, ATV71 and similar), a like-for-like tested replacement is normally faster and cheaper than board-level repair.
Need a replacement Altivar drive? We stock tested Schneider Electric and Telemecanique drives, ready to ship across the EU.
Browse our Schneider Electric range or all Drives & Servos — or send us the catalogue reference from the drive label (for example ATV71HU40N4) and we will match it.
Related reading: Siemens SINAMICS fault codes, common HEIDENHAIN encoder problems, and how to choose used industrial spare parts. For manufacturer documentation, see the official Schneider Electric website.
Frequently asked questions
How do I reset an Altivar fault?
First remove the cause. Then, depending on the fault, it will either clear automatically (such as USF), reset via the reset input or auto-restart (such as OHF), or require a full power-down and restart (such as OCF and SCF). Resetting without fixing the root cause only brings the fault straight back.
What does OCF mean on an Altivar drive?
OCF is an overcurrent fault: the drive detected current above its safe limit. Common causes are an acceleration ramp set too short, excessive inertia or load, a mechanical jam, or a drive sized too small for the motor.
What does SCF mean?
SCF is a short-circuit fault. The variants distinguish a motor short, an earth fault, or a failed output IGBT. Megger the motor and cable first; if those are sound, a shorted IGBT means the drive’s power stage is damaged.
Why does my Altivar keep tripping on ObF?
ObF is a DC-bus overvoltage, usually from braking or decelerating too quickly. The motor regenerates energy faster than the drive can absorb it. Extend the deceleration ramp or fit an appropriately rated braking resistor.
Is Altivar the same as Telemecanique?
Altivar is Schneider Electric’s drive line. It was historically marketed under the Telemecanique brand, so older units carry Telemecanique labelling while being functionally the same product family.
This guide is for general maintenance reference. Always follow Schneider Electric documentation and your site’s electrical safety procedures when working on live drive systems.
