By TEBAOFLEX Jyen. Originally published on December 14, 2025.
A cable connecting a floating wind turbine must accommodate movement as well as transmit power. Selection therefore concerns the complete cable system: the cable, hang-off, bend-control devices, buoyancy modules, touchdown region and any transition to a static section. A fixed submarine cable is not qualified for repeated movement merely because its voltage rating matches.
Use the standards within their scope
IEC 63026:2019 addresses extruded-insulation power cable systems for fixed submarine installations, with rated voltages from 6 kV to 60 kV and specified conditions. Its published scope excludes special dynamic applications such as direct connections to floating structures, which can require modified or additional tests. It does not by itself certify a 66 kV floating-wind cable.
CIGRE Technical Brochure 862, published in 2022, addresses dynamic cable system design, analysis and mechanical testing, including full-scale fatigue testing. It provides a framework for qualification; mentioning it is not evidence that a particular product has passed or will last 25 years.
Describe the floating system before choosing the construction
- Water depth, seabed conditions, turbine and platform motions, environmental load cases and design life.
- Route, suspended length, hang-off orientation, buoyancy arrangement and touchdown movement.
- Operating voltage and earthing, current duty, thermal environment, faults and protection.
- Installation, tow-out, connection, maintenance and emergency conditions as well as normal operation.
A lazy-wave layout uses buoyancy to change the suspended cable shape and its response to platform movement. It can help manage motion but is not automatically suitable for every site. Global analysis should provide tension, curvature and torsion histories at critical locations; local analysis then evaluates the response of the individual cable layers and accessories.
Assess the whole construction, not one material label
Conductor strand arrangement, insulation, water barriers, metallic layers, bedding and armour all influence stiffness and fatigue. Class 5 conductors are not a universal requirement, nor does a Class 2 designation alone establish unsuitability. The selected design needs evidence for the actual dynamic duty.
Radial moisture barriers and longitudinal water blocking perform different functions. Removing a metallic barrier changes the electrical ageing and moisture-control design; changing to a corrugated metal barrier changes mechanical behaviour. Neither is a simple material substitution without renewed assessment.
Opposite-lay armour can help manage torque, but it does not guarantee zero rotation or prevent every hockle. Confirm mechanical properties over relevant temperature and loading ranges and the compatibility of hang-offs, clamps and bend-control devices.
Turn fatigue analysis into a qualification plan
- Define the environmental histories, load cases, design margins and failure modes being assessed.
- Identify critical components and the representative test specimen, fixtures, temperatures and load combinations.
- Agree the test sequence and monitoring: electrical, optical and mechanical checks before, during and after mechanical loading where appropriate.
- Document the criteria for damage, acceptance and the range of designs or operating conditions covered by the qualification.
A number of laboratory cycles is meaningful only with its load amplitude, mean tension, curvature, frequency, environment and failure criteria. A million mild cycles and a million severe cycles are not equivalent. Qualification and routine manufacturing acceptance are different activities and should have separate records.
Do not transfer tow-cable assumptions to power cables
A marine survey tow cable has its own drag, tension, telemetry and handling requirements. Tow speed alone cannot determine winch tension: the cable shape, normal relative flow, wet weight, payload and vessel motion must be considered. A breaking-load value is not an allowable operating load, and forces in different directions must not simply be added as scalars.
Procurement deliverables
Request an approved system drawing, electrical and mechanical design basis, qualification plan and report, manufacturing inspection plan, installation limits and inspection guidance. These are requested deliverables, not a statement that TEBAOFLEX holds unprovided project or test evidence.
Sources and application documentation
Discuss the application
Send the application duty, installation drawing and required acceptance criteria to TEBAOFLEX. WhatsApp: +86 185 9591 3361. Request the applicable product documentation before ordering.