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Cable Protection At Offshore Windfarm

The Case

When an offshore wind farm project gets underway much of the focus tends to be on high value items such as turbines or foundations, or on the availability of installation vessels and crew. The ultimate purpose of the wind farm is to generate and transmit power, and that power is delivered by cables within the tower array, sometimes via offshore substations and finally back to shore by subsea cable.

Some understanding of the mechanics of the installation procedures for these cables and some forward planning can save a large amount of time which can be critical in offshore applications when factors such as weather windows can limit the time available to installation engineers. Typically there will be one cable coming into the base of an offshore tower and one cable coming back out. Usually these cables will have 3 power cores and a fibre optic cable embedded within. To prepare these elements for termination can involve stripping the outer cable back for much longer lengths than the installer normally has to do for onshore situations, this could be as much as 8 metres. This means that consideration has to be given to replacing the removed insulation from the 3 power cores

The Solution

3M Cold Shrink pre-stretched tubes are open-ended, tubular sleeves which are factory expanded and assembled on to a removable core. The core is removed after the tube has been positioned for installation, this method of cable protection allows the tube to shrink and form an environmental seal around the exposed cable.

  • 3M Cold Shrink tubes come in a variety of sizes, able to accommodate a wide range of cable diameters – this offers a flexible solution as often there are at least 2 but on occasion as many as 4 different cable sizes depending on the array layout of any given wind farm.
  • No open flame torches or other heat sources are required by 3M Cold Shrink – a significant advantage from the perspective of health and safety and the burden of extra ‘method related’ documentation.
  • 3M Cold Shrink products are easy to install and there is no delay between installation and energising the cable due to the tube not needing to cool first – this combination leads to increased productivity on site and ultimately a more cost effective job.
  • Distribution Network Operators in the UK and across the world have been using 3M Cold Shrink for more than 30 years where the product has a well earned reputation for consistent reliability – peace of mind for all involved when looking to switch from an existing heat shrink solution.

The Customer

One of the projects where 3M Cold Shrink tubes have been used for this cable protection application in on the Rhyl Flats wind farm in the Irish Channel. Colin Christian, Offshore Electrical Package Engineer for RWE nPower Renewables had this to say about the use of 3M Cold Shrink tubing for this application:

"The selection of 3M Cold Shrink products to provide mechanical protection for the HV cables at Rhyl Flats Wind Farm enabled us to focus on minimising the exposure time of the copper tape screen to the marine environment following stripping. The decision to adopt a cold shrink product in place of heat shrink also removed a significant safety hazard in the use of flammable gases in an enclosed space"