Sveba-Dahlen oLF Error Code

What does Sveba-Dahlen oLF mean?

The SD-180's Schneider frequency converter has detected that the motor is drawing excessive current beyond its rated value over a sustained period. The drive's built-in motor thermal protection function integrates the output current against the motor's thermal model and trips with the oLF fault when the accumulated thermal state exceeds the safe limit, protecting the motor from overheating and winding damage.

Symptoms

• Drive trips with oLF displayed on the touchscreen after a period of high-load operation
• Motor casing is hot to the touch, potentially exceeding safe surface temperature limits
• Fault clears after a cooling period but returns under the same load conditions
• Motor runs but at reduced torque or speed before the fault trip is observed
• Fault is more likely to occur during peak-load process phases (e.g., dense dough mixing or product jams)

Common causes

• Excessive motor output current sustained beyond the motor's thermal rating (primary cause per manual)
• Incorrect motor rated current entered in the drive parameters, causing the thermal model to underestimate actual thermal stress
• Mechanical overload in the driven equipment increasing current demand beyond rated levels
• Motor operating at very low speeds for extended periods without sufficient cooling airflow
• Ambient temperature around the motor elevated, reducing the motor's ability to dissipate heat
• Motor winding degradation increasing resistance and reducing efficiency, causing higher current draw

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Diagnostic steps

1. Verify motor rated current in drive parameters

   In the [MOTOR CONTROL] (drC-) menu, confirm the motor's rated current matches the motor nameplate exactly. An incorrect entry will cause the thermal protection model to miscalculate the overload trip point.

2. Measure actual motor current during operation

   Using the drive's diagnostics display or a calibrated clamp meter on the motor output cables, measure actual running current under load. Compare against the motor nameplate rated current; sustained current above rated value confirms genuine overload.

3. Inspect the driven equipment for mechanical overload

   Check the process equipment for mechanical causes of elevated load such as product buildup, seized components, worn bearings, or misalignment. Resolve any mechanical issues before testing the drive again.

4. Check motor cooling conditions

   Inspect the motor's cooling fan (if fitted), ventilation openings, and surrounding environment. Ensure the motor is not installed in an excessively hot enclosure and that air circulation around the motor body is adequate for the duty cycle.

5. Test motor winding integrity

   With the motor isolated from the drive, measure phase-to-phase winding resistance for balance and perform an insulation resistance test. Degraded or unbalanced windings indicate a motor requiring repair or replacement.

6. Clear the fault after cooling and conduct a monitored test

   Allow the motor to cool to ambient temperature, then clear the oLF fault via the touchscreen. Run the drive under normal operating conditions while monitoring current to confirm it remains within the motor's rated limits.

When to call a professional

Escalate to a licensed technician or Sveba-Dahlen-authorized engineer if measured motor current consistently exceeds rated values even after mechanical issues are resolved, or if winding tests indicate motor damage. Motor replacement, rewinding, or drive resizing requires qualified assessment. Repeatedly overriding or adjusting the thermal protection threshold to suppress the fault without addressing the root cause risks motor failure and is not an acceptable field remedy.