Continuous OTDR sets for Van Oord’s cable-laying vessel Calypso

Offshore wind energy makes a significant contribution to achieving climate goals worldwide. In the construction of offshore wind farms, the vessels of Van Oord play an important role. Van Oord has two cable-laying vessels to install inter-array grid and export cables for offshore wind projects, including high-voltage direct current (HVDC) and interconnector cables. To be fully flexible in continuous OTDR testing, Van Oord decided to purchase two extra portable continuous OTDR sets for its latest cable-laying vessel Calypso. We spoke to Sander Beekhuijzen, Manager Electrical Engineering at Van Oord, about the operations and the new EXFO Continuous OTDR sets from CNRood.

Flexible continuous OTDR testing for monitoring

The Calypso is a cable laying vessel of 131 metres long and 28 metres wide. This DP2 vessel is equipped not only with a cable carousel on deck, but also with a second cable carousel below deck, with a total cable capacity of 8,000 tonnes. To monitor the cable during loading, transportation, unloading, cable laying and burial, monitoring the condition of the integrated fibers in the submarine cable is one of the options. It depends on the project-specific needs whether it is necessary to perform continuous OTDR monitoring on a selected number or even on all fibers in the cable during one or more of the mentioned operations. The present system can monitor 96 fibers simultaneously, in the future this number can be scaled up, even up to to 1024 fibers. To be fully flexible in continuous OTDR testing, Van Oord can deploy, and even remotely control, the two portable continuous OTDR sets wherever needed. This can be on a vessel, at the quayside where the cable is stored, as well as at an offshore substation, beach landing point or in a rotating cable reel.

Verification of Submarine HV (AC or DC) cables

A subsea HV cable normally consists of the HV power cores and one or more integrated fiber-optic cables used for communication and/or conditioning monitoring of the cable system on the seabed. The final total length of the installed cable system ranges from 10 to 100 kilometres or more (e.g. a long DC cable system).  The new OTDR system purchased by Van Oord is suitable for a cable length of up to 100 km, which is more than sufficient for its present intended purpose.

Sander Beekhuijzen: ‘There are two main reasons for testing the cables. The first is monitoring and quality control as part of the transfer of the cable between Van Oord and another party, e.g. during a load-out at the cable manufacturer. The second reason is to check the condition of the cable (fibers) during installation work, think about cable laying or cable burial.

Fortunately, we have never had a problem with a fiber while using the OTDR test equipment. The first system (the previous generation continuous OTDR) was purchased from CNRood in 2019. When a fault is detected, the action taken depends on the detected fault and situation (e.g. an incident). Obviously, it is investigated, and depending on the outcome, a decision is made on how to proceed.’

A standard OTDR is not enough

A new generation of continuous OTDR sets was needed and, of course, a standard OTDR could not meet all needs.

Sander Beekhuijzen: ‘A standard OTDR can only perform an ad hoc measurement that only shows the status at that moment. Certain projects require continuous OTDR monitoring. Van Oord had some specific requirements. The previous systems were fixed systems tied to the vessel. Van Oord wanted a portable system that was not ship-bound and could be deployed wherever needed. Apart from continuous monitoring, there is also often the requirement to provide our client with a final report with OTDR results performed at two or three wavelengths. The purchased system can perform also ad hoc measurements at different wavelengths including reporting with a “push on the button”. In this way we achieve two goals with one device which saves us also a lot of valuable time in connecting and performing the measurements.’

Van Oord opts for EXFO / CNRood solution

There were more suppliers who could provide a continuous OTDR, there are a few reasons to choose EXFO / CN Rood.

Sander Beekhuijzen: ‘We went through an intensive tender process with several suppliers, where we made a choice after a commercial and technical assessment of all the offers. In addition, Van Oord implemented the EXFO Fiber Guardian continuous OTDR (the previous generation continuous OTDR system of EXFO) on one of its cable-laying vessels several years ago, also supplied by CNRood. The equipment, service and support is perceived as very positive which is very important. We were looking for a turnkey solution including support and service. The continuous OTDR had to be built into a portable case suitable for offshore use worldwide. For this reason the case had to be equipped with  temperature and humidity control. In addition, a separate alarm-unit which could be connected to warn the operator in case of an error.’

Excellent cooperation with Van Oord and CNRood

Van Oord is very satisfied with the cooperation and the results of the project.

Sander Beekhuijzen: “The biggest challenge for CNRood was getting the complete system delivered on time. This was probably mainly caused by the fact that this system was a new development. Fortunately, there was no real time pressure and Van Oord was able to give CNRood enough time to get the two systems ready. Van Oord was well aware that by giving CNRood the time, the completed system would be of  higher quality. Looking at the end result, this extra time was more than worth it!

Cooperation throughout the project was perfect. Although it took a little more time than initially planned, the result is excellent. We still have to see how the equipment functions in the field which will be soon, but the Acceptance Test has shown that the system functions according to Van Oord’s specifications. The communication between CNRood and Van Oord’s specialists was very good and CNRood’s approach of thinking in technical solutions rather than just commercially is highly valued. In the offshore industry where Van Oord operates, unreliable equipment is simply not acceptable, as it results in high risks and delays during very costly operations.”