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Diagnostic workflow

Schneider ATV61 / ATV71 OSF and USF DC-Link Diagnostic Workflow

Entry symptom: ATV61/ATV71 reports OSF overvoltage or USF undervoltage during power-up, run or deceleration.

Safety controls before proceeding
  • DC-link work is hazardous even after stop.
  • Verify discharge with suitable meter and procedure.
  • Do not bypass braking or supply protection.

Investigation sequence

1

Separate OSF from USF

Overvoltage and undervoltage point to opposite DC-link conditions and must not be merged into one generic supply fault.

2

Measure input

Measure all input phases at the drive terminals under relevant plant conditions.

3

Classify event timing

Power-up USF suggests input/precharge; deceleration OSF suggests regeneration, ramp or braking path.

4

Check braking path

For OSF during stop, inspect brake resistor/chopper wiring and suitability where fitted.

5

Inspect DC-link path

Only after safe isolation, review rectifier, precharge and capacitor evidence.

Stop conditions

  • Input voltage cannot be measured
  • DC bus is not verified discharged
  • Regenerative load cannot be safely tested
  • Brake resistor overheats

Linked records

OSF
DC Bus Overvoltage / Supply Overvoltage

The drive sees excessive DC-link voltage. The first boundary is line voltage, regeneration during decel, braking path and ramp configuration.

Open →USF
Undervoltage / Supply Loss Fault

The drive does not have adequate input/DC-link voltage. The route begins at line supply, fuses, contactor, precharge and DC-link condition.

Open →Circuit
Schneider ATV61 / ATV71 Input and DC-Link Path

Routes USF and OSF evidence through input phases, fuses, contactor, rectifier, precharge, DC-link capacitors, braking path and DC-bus measurement.

Open →