Schneider Electric Altivar Machine ATV320 fault OBF: DC bus overvoltage
OBF on a Schneider Altivar ATV320 is a DC bus overvoltage error: the DC bus voltage rose too high and the drive tripped. Schneider gives braking that is too sudden, a driving (overhauling) load, or a supply voltage that is too high as the causes.
Diagnose this with AI
Try Free Drive Diagnostic Upload a keypad photo, the fault history or a parameter export from your Schneider Electric Altivar Machine ATV320. InduQT compares the evidence and suggests the next useful checks.
When it happens
- During deceleration or stopping
- With an overhauling load driving the motor
- At any time if the supply voltage is high
Likely causes and checks
1Deceleration too fast for the inertia
- Points to it
- Trips only on stops or speed reductions.
- Check
- Increase [Deceleration] DEC and see whether the trips stop.
2No braking resistor where the duty needs one
- Points to it
- Fast stops of heavy loads, or a load that drives the motor.
- Check
- Install a braking resistor if necessary, sized per Schneider’s data.
3[Dec.Ramp Adapt] BRA off
- Points to it
- No resistor fitted; BRA set to No.
- Check
- Activate BRA if compatible: Schneider says it is incompatible with positioning on a ramp and with a braking resistor, and it is forced to No when brake logic is assigned.
4Supply voltage too high
- Points to it
- Trips even at standstill or on gentle stops; OSF may also appear.
- Check
- Measure the supply voltage at the drive input and compare with the drive rating.
Telling it apart
- OBF is a DC bus overvoltage, usually regenerative; OSF is supply mains overvoltage or a disturbed supply.
- Timing: OBF on deceleration points to DEC, braking resistor or BRA; OBF with no stop in progress points to the supply.
- OBF can be cleared by [Auto Fault Reset] ATR or the RSF input once the cause is removed.
Relevant parameters
| Parameter | Name | Why it matters |
|---|---|---|
| DEC | Deceleration | 0.00 to 6,000 s; factory setting 3.0 s. |
| BRA | Dec.Ramp Adapt | Adapts the deceleration ramp to avoid overvoltage. With a permanent magnet motor, only use Yes or No; other settings can demagnetize it. |
Evidence to collect
- Error history record for OBF, including mains voltage (ULP1)
- DEC setting and stop type
- BRA setting
- Braking resistor fitted and its value
- Supply voltage
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