ATV630 Fault Codes: Schneider Altivar Troubleshooting Guide

Schneider Electric's Altivar Process ATV630 communicates problems through error codes shown on the graphic display terminal — short alphanumeric labels like OCF, SCF1, OHF, USF, CFF, EPF1, and a long list of internal codes. When the drive trips, getting back to production fast depends on reading the right code, knowing whether the cause is in the drive, the motor cable, the load, or the supply, and clearing the error correctly.

This guide is for maintenance engineers and system integrators servicing ATV630 (and the closely related ATV930) drives in pumping, fan, compressor, and general industrial applications. Every code, parameter mnemonic, and reset behavior below comes from the official Altivar Process Programming Manual (EAV64318). Codes that vary by firmware are noted; uncommon internal codes are summarized rather than expanded so this stays a working reference instead of a wall of text.

How ATV630 error reporting works

When the ATV630 detects a condition it cannot operate through, it stops the motor, displays an error code (for example [Overcurrent] OCF) on the HMI, and writes the event to the error history ([Last Error 1] LFt1 through LFt8). Each code has one of three reset behaviors:

• Auto-clearing — the error clears as soon as the cause disappears (USF, PHF).
• Manual reset or Auto Fault Reset — clearable via the [Fault Reset Assign] rSF input or [Auto Fault Reset] Atr after the cause is gone (OHF, OLF, EPF1).
• Power reset required — the drive must be fully powered down before it will run again (OCF, SCF1, SCF3, SCF4, SCF5, ObF, tJF).

Knowing the reset class up front matters: if you keep pressing the HMI reset button on a code that needs a power cycle, you'll waste time before realizing the drive cannot recover from the keypad.

Quick-reference table: ATV630 error codes

Power-stage and motor-cable errors

This is where most ATV630 service calls land. The error code points at a power-stage event, but the root cause is usually upstream in the cable, motor, or load.

OCF — Overcurrent

What it means: Output current exceeded the drive's instantaneous trip threshold. The drive cannot continue operating safely.

Probable causes (per Schneider): Parameters in the [Motor data] MOA- menu are incorrect; inertia or load is too high; mechanical locking on the driven equipment.

Troubleshooting checklist:

1. Verify motor nameplate values against [Motor data] MOA- — rated voltage, current, power, frequency, speed, and cosphi must match the motor on the shaft.
2. Re-check the size of motor / drive / load: oversized inertia or chronic overloads cause repeat OCF on every accel ramp.
3. Inspect the mechanism for binding: seized bearings, jammed conveyors, or a flooded pump suction.
4. Decrease [Current limitation] CLI to a value the drive can sustain.
5. Increase the switching frequency ([Switching frequency] SFr) to soften peaks on long cables.

Reset: Power cycle. The keypad reset will not clear OCF.

SCF1 — Motor short circuit

What it means: The drive detected a short circuit or grounding at its output. Continuing to run risks IGBT damage.

Causes: Phase-to-phase or phase-to-ground short in the motor cable, degraded motor insulation, dV/dt-induced standing waves on long cables.

Troubleshooting:

1. Disconnect the motor cable at the drive output. Megger each phase to ground (a healthy 480 V motor reads >1 MΩ at 500 V DC; below 100 kΩ is failed insulation).
2. Check the motor junction box for water ingress, lugged connections that have arced over, or rodent damage.
3. On long cable runs (over 50 m unshielded or 100 m shielded), reduce switching frequency or fit a dV/dt or sinusoidal output filter.
4. Verify speed-loop and brake adjustments — aggressive torque ramps can trigger transient SCF1 even when the cable is good.
5. Increase [Time to restart] ttr if the fault appears only during automatic restart sequences.

Reset: Power cycle.

SCF3, SCF4, SCF5 — Ground / IGBT / Motor short variants

SCF3 indicates significant ground-leakage current at the output (typical when several motors run in parallel or one motor's insulation has degraded but not yet failed). SCF4 is internal IGBT desaturation — almost always a power-stage failure. SCF5 fires during the start sequence when the drive's pre-start short test detects an issue. All three require a power reset.

For SCF3, run the same megger procedure as SCF1 but include each parallel-connected motor individually. For SCF4 on a unit that previously ran cleanly, the path is usually a service replacement — the IGBT module has failed.

OPF1 / OPF2 — Output phase loss

OPF1 is one missing output phase, OPF2 is all three (no current detected on output). Causes are loose terminations, contactors with worn poles between drive and motor, blown output fuses, open motor windings, or a broken cable.

Field check: measure phase-to-phase resistance at the motor terminals — a small motor reads a few ohms, larger motors below one ohm, but the three readings should be approximately equal. A reading several times higher (or open) on one phase points at the winding. If readings are good, the break is in the cable or contactor.

OPF1/OPF2 detection can be configured via [Output Phase Loss] OPL; on bypass or sleep applications you may need to disable it.

ObF — DC Bus Overvoltage

The DC bus exceeded its maximum during deceleration or regeneration. The classic cause is decel time too short for an inertial load with no braking resistor.

1. Increase [Deceleration] dEC or, where the application allows, enable [Dec ramp adapt.] brA so the drive automatically extends decel when bus voltage rises.
2. For genuinely high-inertia loads (large fans, centrifuges, flywheels), fit a dynamic braking resistor sized to the regen power. The drive's brake transistor is built in; only the external resistor needs adding.
3. Verify supply voltage at the drive input — a 480 V drive on a 525 V network sees ObF much sooner.

OHF and tJF — Drive and IGBT overheating

OHF is heatsink temperature; tJF is calculated IGBT junction temperature from the thermal model. Causes overlap: blocked cooling fans, clogged heatsink fins, ambient above the cabinet derating curve, undersized enclosure, or sustained over-load.

1. Confirm cooling fans are spinning and pulling air the right way. ATV630 fans pull bottom-to-top — anything blocking the bottom inlet or the top exhaust kills cooling.
2. Measure cabinet ambient near the drive (not at the door). Most ATV630 sizes are rated to 40 °C ambient before derating.
3. Maintain the keep-out clearance specified in the installation manual (typically 50–100 mm above and below depending on frame).
4. Vacuum heatsink fins. In dusty plants, schedule this as preventive maintenance every 6–12 months.

OHF clears manually or via Auto Fault Reset once the drive cools; tJF requires a power reset because the thermal model has flagged a hardware-protection event.

Motor and load protection errors

OLF — Motor Overload

The drive's motor thermal model (I²t) determined the motor has been running above its full-load amps long enough to risk thermal damage. This is the drive protecting the motor, not protecting itself. Verify motor FLA in the [Motor data] menu first — incorrect rated current is the #1 cause of nuisance OLF trips. Then look at sustained current via the monitoring menu and at the actual load: blocked impellers, mistuned PID loops, or shrinking cooling clearance on the motor itself.

OLC and ULF — Process Overload / Underload

These come from the process monitoring functions, not the motor thermal model. OLC fires when the load exceeds [Process Overload Threshold]; ULF fires when load drops below [Process Underload Threshold]. ULF is the standard "broken belt" or "dry pump" indicator on a fan or pump.

SOF — Motor Overspeed

Actual speed exceeded [Max Frequency] HSP plus tolerance. Common in pumps and fans with regenerating loads where deceleration is allowed to coast. Check encoder configuration if a feedback device is fitted, and verify the speed-reference path.

tnF — Autotuning Error

Autotuning could not complete. The motor must be at standstill, properly wired, with correct nameplate data entered before the tune is launched. Common pitfalls: tuning with the brake not released on a hoist, tuning a star-connected motor with delta nameplate, or tuning over a long cable without an output filter that the tune can model.

Supply-side and configuration errors

USF — Supply Mains Undervoltage

Mains too low or a transient dip pulled DC bus below the run threshold. USF auto-clears as soon as the cause disappears, so a brief flash on the keypad after a momentary sag is normal. Persistent USF means the supply is undersized, the input feeder is loose, or the upstream contactor is dropping out. Tune the response with the [Undervoltage handling] USb menu — options include immediate trip, controlled stop, or ride-through.

PHF — Input phase loss

One of three input phases missing or the supply is severely unbalanced. Check fuses and incoming terminations. PHF clears automatically once balance returns. If a 3-phase ATV630 is intentionally fed from single-phase (only valid on specific small frames), set [Input phase loss] IPL = nO.

OSF — Supply Mains Overvoltage

Line voltage above the drive's tolerance band. Check transformer tap setting, neutral integrity, and (on weak rural feeders) line voltage during low-load periods when it tends to drift up.

CFF / CFI / CFI2 — Configuration errors

CFF appears at power-on when an option module that was previously installed is now missing, has been replaced by a different module, or the firmware no longer recognizes it. The remedy is the menu choice "Use the connected option" or the explicit reload of a saved configuration. CFI/CFI2 indicate the parameter set itself is invalid or the SoMove transfer failed — restore from backup or factory reset and re-commission.

Communication and I/O errors

EPF1 / EPF2 — External / Fieldbus errors

EPF1 fires when a digital input configured as [External error] is activated. Trace the wired device — common sources are vibration switches, motor PTCs wired to a relay, gas-detection triggers, or an upstream PLC's fault relay. EPF2 is the same concept but flagged via fieldbus from the master controller.

CnF, EtHF, COF, SLF1/2/3 — Communication interrupts

The drive lost cyclic communication with its master beyond the configured timeout. Check link/activity LEDs first (drive port and the upstream switch port), verify no IP conflicts, then look at the timeout setting under the relevant [Communication] submenu. Intermittent CnF/EtHF on a properly configured network often traces to a marginal cable, a flapping switch port, or PLC scan time spikes.

LFF1–LFF5 — Analog input loss

Analog input below the loss-detection threshold (usually below 4 mA on a 4–20 mA loop). Measure the loop current with a clamp meter or a series milliammeter, check transmitter power, and verify the input is configured for 4–20 mA rather than 0–20 mA.

SAFF — Safety Function Error

The integrated safety functions (STO, SS1, SLS depending on options) detected an internal mismatch or a wiring violation. SAFF requires a power reset and, on persistent occurrence, the safety wiring must be checked against the dedicated safety installation manual — both STO inputs must be energized in agreement, redundancy violations are caught.

Wiring and parameter quick-reference

The fastest way to eliminate ATV630 nuisance trips is to get wiring and the [Motor data] menu right at commissioning.

• Power terminals — L1/L2/L3 input on top, U/V/W output on the bottom. PE bonded to the cabinet ground bar with a star configuration.
• Motor cable — symmetrical shielded VFD cable for runs over 30 m, 360° EMC-clamped at both ends. Unshielded cable above 50 m frequently triggers SCF1 / SCF3 due to standing waves.
• STO inputs — STOA and STOB must both be energized for the drive to enable. If not used, jumper to +24 V per the installation manual; do not float them.
• [Motor data] MOA- — set [Nom Motor Voltage] UnS, [Nom Motor Current] nCr, [Nom Motor Freq] FrS, [Nom Motor Speed] nSP, [Nom Motor Power] nPr, [Nom Motor Cosinus Phi] COS exactly from the nameplate. Run autotune ([Autotuning] tUn) once values are entered.
• Switching frequency — [Switching frequency] SFr default 4 kHz. Increase to 8 or 12 kHz on long cables to reduce dV/dt; expect derating per the manual.
• Ramps — [Acceleration] ACC and [Deceleration] dEC. On regen-prone loads, enable [Dec ramp adapt.] brA.
• Reset — assign [Fault Reset Assign] rSF to a digital input for remote reset.

Decision tree: replace or repair?

After you've worked the troubleshooting list above, some failures clearly point at hardware that has reached end of life. Here's a practical decision tree.

• Repeat OCF or SCF1/SCF3 with cable and motor confirmed good — output stage damage, replace the drive or send for power-board service.
• SCF4 (IGBT short) — power module failure, replace the drive.
• tJF without elevated heatsink temp — IGBT thermal sensor or junction has aged, replacement recommended.
• EEF1 / EEF2 recurring after factory reset — control board memory failure, replace the control board or drive.
• InF series internal errors — most are hardware diagnostics. Single-occurrence after a power event may clear; repeat occurrences mean replacement.
• HCF Boards Compatibility — control board and power board have a firmware/hardware mismatch. Either restore the original board or update both.
• ASF (Angle error) on a PMSM — encoder or rotor alignment issue. If the motor is a known-good Schneider PMSM, the issue is electrical alignment; otherwise re-tune.

When you've decided to replace, source the exact catalog number from the nameplate (ATV630D11N4 differs from ATV630U22N4 in frame, kW, and spare-part availability). Rabwellplc stocks Altivar Process drives across the ATV630/ATV930 range alongside compatible Schneider VFD spares and option modules; cross-reference legacy ATV61/ATV71 part numbers if you're upgrading from older Altivar generations.

Preventive practices

• Quarterly — verify cooling fan operation, check air-filter cleanliness, log error history (LFt1–LFt8) and look for repeat codes.
• Semi-annually — torque-check power terminations to spec (loose terminations cause OCF, OPF, and SCF1 over time), measure motor insulation resistance to baseline.
• Annually — vacuum heatsink, inspect option-card seating, verify firmware against the latest Schneider release, back up configuration via SoMove or the Graphic Display Terminal.
• After any trip — read the error history before clearing it. The order of preceding warnings (for example, an OHt warning before an OHF trip) usually reveals the real cause.
• On installation — record commissioning parameter set as a "golden config" file and store it with the maintenance documentation. Restoring a known-good config from CFI/CFF is far faster than rebuilding from scratch.

FAQ

What is the difference between an OCF and a SCF1 trip?

OCF is an output current excursion above the instantaneous limit — usually a load or parameter problem. SCF1 is the drive's short-circuit detection circuit firing because phase-to-phase or phase-to-ground impedance dropped to near zero — usually a cable or motor insulation problem. Both require a power reset, but the troubleshooting paths differ: OCF means review the load and motor data, SCF1 means megger the cable and motor.

Why does my ATV630 show CFF every time I power up?

CFF means an option module is installed differently from when the drive was last configured — added, removed, or replaced. The HMI offers two choices when CFF appears: accept the new configuration and continue, or reload the saved configuration. If you never installed an option in the first place, the cause is usually a control board that was swapped from another drive that had options. Restore-to-factory followed by re-commissioning clears it.

Can I disable input phase loss detection (PHF) to run from single-phase?

Only on drive frames that are explicitly listed as single-phase capable in the catalog. On those, set [Input phase loss] IPL = nO. On 3-phase-only frames, running from single-phase will damage the input rectifier even with PHF disabled — the protection is correctly stopping you from doing it.

What's the right way to clear an SCF1 or OCF after I've fixed the cause?

Power down the drive completely, wait for the DC bus discharge LED to extinguish (or the time specified on the front cover, typically 15 minutes), then re-energize. The keypad Stop/Reset button does not clear power-reset-class faults — this is intentional, to force you to verify the DC bus is safe before approaching the terminals.

How many error history entries does the ATV630 keep?

The drive logs the last eight events in [Last Error 1] LFt1 through [Last Error 8] LFt8, with timestamp, drive state, motor current, DC bus voltage, and frequency at the moment of trip. Always read this history before clearing — the chain of preceding warnings often shows the root cause more clearly than the final trip code.

Need a replacement ATV630, ATV930, or option module? Browse our in-stock Schneider Altivar Process drives and accessories, or pair with a compatible Modicon PLC for retrofit projects. For on-the-bench drives that have failed beyond field repair (SCF4, repeat InF errors, EEF1/EEF2), our team can cross-reference your existing catalog number to a current-production equivalent.