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Temporary connection to DP system caused short circuit – DP undesired event

Comments:

Various DP equipment, including the DP status lights, were connected via UPS No. 2. Investigation found that the UPS tripped because of a break in the portable cable supplying the DP status lights to ROV control.

  • The vessel does not have a permanent ROV system, when an ROV system is mobilised it is a requirement that the ROV control has DP status lights. This is achieved by installing a portable set of lights that are connected to the vessel’s DP system by a cable.
  • The same cable had been in use for several years whenever an ROV system was mobilised.
  • Inspection procedures have been modified to include portable wiring and a bend preventer/limiter used for future connections.

Considerations from the above event:

  • Connection of ANY temporary system to a DP system should be as part of a formal management of change and properly risk assessed.
  • The connection of ANY temporary system should be designed to tolerate a short circuit or any other failure.
  • Additional systems that are connected to a DP system should be approved by manufacturer and class and should be extensively tested.
  • The vessel is recorded as operating within DP equipment class 2, however only satellite derived position reference systems were recorded as being in use.

DP Event

Published: 2 November 2017
Download: IMCA DPE 04/17

Classification:
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The following case studies and observations have been compiled from information received by IMCA. All vessel, client, and operational data has been removed from the narrative to ensure anonymity.

Case studies are not intended as guidance on the safe conduct of operations, but rather to assist vessel managers, DP operators and DP technical crew in appropriately determining how to safely conduct their own operations. Any queries should be directed to IMCA at dpreports@imca-int.com. Members and non-members alike are welcome to contact IMCA if they have experienced DP events which can be shared anonymously with the DP industry.

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