Nexans qualifies HVDC cable for 3,000-meter deepwater installation

Power transmission specialist Nexans has achieved a significant technological milestone, successfully qualifying a 525 kV high-voltage direct current (HVDC) mass-impregnated (MI) cable system for installation at a record depth of 3,000 meters. This accomplishment sets a new world record for submarine power cable installation depth and positions Nexans as the sole manufacturer with a qualified system for this extreme environment.

The qualification was completed as part of the Great Sea Interconnector (GSI) project, which aims to link Crete and Cyprus via a ±525 kV HVDC subsea transmission link. The entire system, including a flexible repair joint, has undergone rigorous mechanical and electrical type testing. During testing, the cable system endured a mechanical tension of up to 842 kN, simulating the demanding conditions at 3,000 meters underwater.

Nexans also conducted a full-scale sea trial at 3,000 meters in March 2026. In this trial, a Nova-L 525 kV 1×1300 mm² aluminum MI cable and its joint were installed and recovered under actual offshore conditions. Subsequent electrical testing and inspection confirmed the system's robustness and ability to withstand the stresses of the deepwater installation process.

The ability to install cables at 3,000 meters significantly expands the technical and economic feasibility of future subsea interconnections and offshore power transmission schemes. Previously, depths exceeding 2,000 meters were often considered too risky, costly, or technically unachievable for cable systems. This new technology enables shorter transmission routes, simplifies routing challenges, and reduces environmental impact along coastlines.

Nexans presented this breakthrough technology and the associated experiences at the CIGRE Paris Session 2026, held from August 23–28. The event brought together international power systems experts to discuss the future of the industry and its latest innovations.