FEATURE
IMPROVED POWER CABLES DEPLOYMENT: Control of Touchdown Tension is Critical to Successful Submarine Power Cable Installations BY DR. VENKATA K. JASTI AND DR. JOSE ANDRES
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n the recent years, there has been an increase in submarine power cable installations, and industry predictions estimate that such installations will continue to increase primarily due of two factors: First, offshore wind energy installations continue to increase particularly in Northern Europe, where installations are moving to “Phase 3s” which involves installations further offshore that require longer export cables. Second, there is an increase in grid interconnection cables between countries with surplus power and those with high demand. In both these cases, installations will involve longer routes and deeper waters. All studies on submarine power cable failures point to installation issues as one of the leading causes of failures to date. To prepare for the future, installers need to quickly learn to rectify installation issues experienced in the past
and apply improved methods to the more challenging installations of the future. Submarine power cable installation is a complicated process with many overlapping steps. In this article, the focus is on improvements that can be made in planning and installation phases to maintain proper cable tension during installation to avoid some of the typical failures.
ESTABLISHING “PLANNED BOTTOM TENSION”
Maintaining a proper cable tension at the touchdown point is a critical step in avoiding some of the common causes of failures during the installation. If a cable is installed with too high a bottom tension, cable spans will be created on the seafloor resulting in heavily loaded contact points along the cable as seen in Figure 1a. When the cable is exSEPTEMBER 2018 | ISSUE 102
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