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What can cause a DC Bus Overvoltage fault on Altivar Process?

Published date: 09 July 2019

Altivar Process Drive tripped on DC Bus Overvoltage, obF.

Product line:
ATV630, ATV930, ATV650, ATV950


DC bus voltage too high


The fault appears when ramp adaptation is not possible (BRA=NO), the inverter is switched on and the DC bus voltage reaches the OBF level. The error could be detected by the AFE and the BUO
and send to the Master control block.

OBF Fault
  Description 400V Range [Vdc]
OBF Overvoltage threshold after charging and during operation 820V
OBR Switch on threshold for external braking unit 800V
BRA Threshold for adaptation of the deceleration ranp 781V


Probable cause:
  • Braking too sudden or driving load.
  • Braking unit option cannot convert the "braking energy" into heat.
  • Overvoltage at the input.
  • Motor short to ground
  • Increase the deceleration time.
  • Activate the BRA function (deceleration ramp adaptation) if it is compatible with the application.
  • Check the motor wiring at the pecker head of the motor.

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