Schneider ATV320 Fault Codes: OCF, SOF, EPF1, LFF3 and More

PHF, OPF, and Output-Side Faults

PHF relates to the input power side. Check incoming phases, fuses, contactors, supply imbalance, and loose terminals.

OPF1 or OPF2 points toward the output side. Check the motor cable, U/V/W terminals, motor connection, and whether the motor is connected when the drive expects it.

For SCF type trips, stop and test carefully. Short-circuit and ground-fault trips can involve damaged cable insulation, motor winding failure, moisture in the terminal box, or wiring mistakes.

Power down, wait according to Schneider’s safety instructions, verify absence of voltage, then inspect and test. Never megger a motor while it is still connected to the drive output terminals.

How to Read ATV320 Fault History

The ATV320 stores fault information that can help you avoid guessing.

Useful information normally includes the current fault, previous fault history, drive state, and operating values around the trip depending on the display or commissioning tool used.

When troubleshooting, record:

• Exact fault code on the display
• When it happens: power-up, start, acceleration, constant speed, deceleration, stop
• Motor current at trip
• Speed or frequency command
• Load condition
• Recent parameter or wiring changes
• Whether the fault resets immediately or returns at the next run command

This small record often saves hours.

A fault that appears instantly at run command is usually different from a fault that appears after 20 minutes of operation.

Safe Reset Procedure

Reset only after the fault cause is understood or removed.

A basic reset may be done from the drive keypad, control input, communication command, or power cycle depending on how the ATV320 is configured.

Before resetting:

• Confirm the run command is off
• Make sure the machine cannot restart unexpectedly
• Check whether the fault is external, electrical, thermal, or mechanical
• Record the fault code first
• Do not repeatedly reset overcurrent, short-circuit, or overheating faults

Schneider Electric manuals include important warnings about stored energy in the DC bus. Before wiring or inspection, isolate power, wait the required time, and verify voltage according to the installation manual.

Practical Troubleshooting Sequence

Use this order when the cause is not obvious.

1. Record the exact code.

Do not translate OCF, SOF, EPF1, and LFF3 into vague notes like “drive alarm.” The exact code matters.

2. Identify when the fault occurs.

Power-up faults point toward configuration, supply, or internal hardware. Run-command faults often point toward motor/output wiring. Acceleration faults often involve current and torque. Deceleration faults often involve regeneration.

3. Check recent changes.

Most inverter faults after maintenance are caused by changed wiring, replaced motor, modified parameters, swapped sensor, or changed PLC logic.

4. Check power and wiring.

Inspect incoming supply, grounding, motor cable, shield, terminal torque, contactors, and analog/control wiring.

5. Check motor and load.

Separate the electrical drive problem from the mechanical load problem. A jammed gearbox can look like a drive problem if you only read the display.

6. Review parameters.

Confirm motor nameplate data, ramp times, current limits, control mode, analog input assignment, logic input assignment, and communication settings.

7. Replace only after evidence points there.

If the drive has repeated internal faults, visible damage, failed fan, damaged terminals, or trips with a known-good motor and wiring, replacement may be justified.

When sourcing a replacement through Kwoco, send the full ATV320 model number, motor nameplate, application type, current fault code, and parameter backup if available. That makes model matching and accessory checking much safer than choosing only by kW rating.