Sveba-Dahlen oCF

What does Sveba-Dahlen oCF mean?

The SD-180's Schneider frequency converter has detected an overcurrent condition on the motor output. The drive measures output current exceeding the permissible threshold and trips to prevent damage to the converter's power stage and the motor. Per the SD-180 manual, this can result from incorrect parameters in the SETTINGS or MOTOR CONTROL menus, a load or inertia that exceeds drive capacity, or a mechanical obstruction in the driven equipment.

Symptoms

• Drive trips immediately on startup or during acceleration with oCF displayed on the touchscreen
• Motor fails to reach running speed and stalls with the drive in a fault state
• Fault may occur only under load but not during a no-load test run
• Overcurrent trip happens at a predictable point in the speed ramp or duty cycle
• Physical evidence of mechanical resistance such as unusual noise or seized components in the driven equipment

Common causes

• Incorrect motor control or settings parameters in the [SETTINGS] (SEt-) or [MOTOR CONTROL] (drC-) menus (primary cause per manual)
• Load or inertia too high for the configured drive output capacity
• Mechanical blockage or seizure in the motor-driven equipment
• Acceleration ramp time too short, causing excessive current demand during speed ramp-up
• Motor nameplate data (rated current, voltage, frequency) entered incorrectly into the drive
• Motor winding fault causing abnormally low impedance and high current draw

Diagnostic steps

1. 01

   Verify motor nameplate data in drive parameters

   In the [MOTOR CONTROL] (drC-) menu, confirm that rated voltage, rated current, rated frequency, rated speed, and power factor match the motor nameplate exactly. Correct any discrepancies and re-run auto-tune if required.

2. 02

   Check for mechanical blockage

   Disconnect the motor from the load mechanically (if safe to do so) and attempt a no-load run. If the fault clears without the load, the problem lies in the mechanical system; inspect for seized bearings, jammed conveyor, or obstructed mixing equipment.

3. 03

   Increase the acceleration ramp time

   In the [SETTINGS] (SEt-) menu, increase the acceleration ramp time (ACC parameter) to reduce the rate of current rise during startup. High-inertia loads require longer ramps to avoid overcurrent on acceleration.

4. 04

   Review and correct motor control settings

   Check the [MOTOR CONTROL] (drC-) menu for correct control mode selection (e.g., U/f, sensorless vector) and verify boost voltage or IR compensation settings are appropriate for the motor and load. Revert to factory defaults and recommission if settings are uncertain.

5. 05

   Measure motor winding resistance and insulation

   With the motor isolated from the drive, use a multimeter to check phase-to-phase winding resistance balance and an insulation resistance tester to check for winding faults. Replace the motor if winding faults are found.

6. 06

   Clear the fault and conduct a loaded test run

   After all corrections, clear the oCF fault via the touchscreen and perform a monitored test run under normal operating load, observing current readings in the drive diagnostics to confirm they remain within rated limits.

When to call a professional

Escalate to a licensed technician or Sveba-Dahlen-authorized engineer if the fault persists after verifying parameters and clearing mechanical obstructions, particularly if the motor or converter shows signs of damage. Motor rewinding, drive power stage replacement, or application-specific recommissioning require qualified expertise and should not be attempted without proper authorization and test equipment.