Failure of DP UPS – DP undesired event

Comments from the Report:

The vessel maintained position but DP equipment class 2 capabilities were compromised.  It was noticed that there was a strong burning smell from the UPS.  The UPS was still powered up from the ships supply but it was in internal bypass.  Tests were carried out and it was noted that there was no voltage or frequency output.  The voltages on the eight external batteries were checked and all but one had 12+ Volts.  One of the batteries had 10 volts.

The replacement unit was tested extensively, and it operated satisfactorily.

Considerations of the IMCA Marine DP Committee from the Above Event:

  • The status of the UPS should be verified on pre-operational checklists.
  • Battery and UPS tests should be part of the DP annual trial programme and subject to regular maintenance.
  • It should be noted that with one diesel generator on each bus, a partial black-out may occur in case of failure. This should be included in the operational activity planning.
  • It appears the vessel responded as designed and the situation was well handled by the vessel crew.