SEANEX - High-voltage connection for inter-array cabling

SEANEX is a dry pluggable inner cone connection and contact system specifically for offshore applications up to 72.5 kV. It is based on the CONNEX system by PFISTERER for voltages up to 550 kV. SEANEX components have been optimised for requirements at sea, are DNV GL certified and meet the new IEC 63026 offshore standard.

  • Proven HV connection system
  • Quick and simple installation
  • Separate electrical and mechanical contact
  • Touch-safe
  • Offshore certified by DNV GL
  • Salt water resistant
  • Maintenance-free

With SEANEX, PFISTERER offers a robust inner cone HV connection system for 66 kV offshore applications. In addition, connections and links up to 550 kV can be implemented with the CONNEX system. Shipbuilding materials are used for all SEANEX components. They are fully submersible and salt water resistant, without affecting the service life.


Constructing an offshore wind farm is a huge task for everyone involved. After completion, power generation and distribution has to be guaranteed for a minimum of 25 years. The electrical installations in modern offshore wind farms operate at 66 kV high voltage - and rising.

Compared to constructing the wind farm, connecting and linking the electrical systems is a small though significant part. It is only with reliable interfaces that the electricity supply from offshore wind farms can be guaranteed. Yet some operators rely on medium-voltage connection technology at precisely these sensitive interfaces - not without risk.

66 kV on the safe side!

Separate electrical and mechanical contact

Compared to other connection solutions, SEANEX is the much more robust system. Electrical and mechanical contacts are separate from one another. The proven lamella contact technology and spring system ensure reliable power transmission - even during sudden load changes. For installation, the SEANEX connectors simply plug into the corresponding sockets and joints, and are secured with threescrews. The rotatable bell flangeen- ables 360° installation.

Advantages connection joint

The cast resin connection joint in the SEANEX system enables rapid connection of the wind turbine to the wind farm network. All that is required offshore is to fit the pluggable connectors to the seaward cables. The attachment of the joints using four screws can be carried out on land. All cable sections between the joint and switchgear and between switchgear and transformer are supplied preassembled, pretested and ready to plug in. There is no longer any need to test these preassembled cables offshore.

  • Electricity flows in a line - no angles, corners or edges
  • Transition box is eliminated
  • Touch-safe thanks to metallic encapsulation
  • No twisting of cable
  • Connection can be separated without loss of quality
  • Very short offshore installation time 
  • Clear interface between sea cable and wind turbine
  • Establishes clear responsibilities for each construction and project phase
  • Joint can be used as test equipmentwith dummy plug


This project is unique worldwide. DolWin gamma is one of the first and largest commercial offshore converter stations in the German North Sea. As part of the DolWin network connection project, it has been connected to another platform via a bridge system, using a new kind of flexible high-voltage cable with a conductor cross-section of 800 mm².


14 staff, 13 weeks, 5,800 meters of cable: PFISTERER installed the first ever cable system certified for off-shore use at the Global Tech I off-shore wind farm.


The cable system in the dry dock, the test transformer far away on the back of the truck. HV tests for off-shore systems can be pretty tricky. A PFISTERER-developed adapter solves this problem.


Q7 is the Netherlands’ first off-shore wind farm outside of the territorial zone (12 nautical miles). Here, CONNEX cable connections are not the only things that need to show off their sea legs. PFISTERER experts have to showcase their bravery, too.


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