TECHNOLOGY BLOG: 66KV (72.5KV) CABLE DEVELOPMENT

: Jeremy Featherstone, product development director, explains the subsea power cable system’s qualification programme

66 (72.5) kV cable technology is critical to support the offshore wind industry as it moves to increased power transmission between turbines at higher capacity offshore windfarms. At JDR, we have pioneered the design of inter-array cables in the offshore energy industry, contributing to cost reduction targets with innovations such as aluminium cores.

Our new high voltage cable recently completed its qualification and type testing programme, including terminations and accessories. The cable underwent all type tests required for full qualification of a 66kV subsea power cable system. It is now in full accordance with IEC60840 and Cigre 490 international standards. The qualification covers cable up to and including 630mm² conductor size, for both coilable and non-coilable storage and installation configurations. This allows greater offshore installation flexibility for our customers. The qualification programme also included cable system testing of end connectors and qualification of factory flexible and rigid field repair joints.

In addition to the 66kV type test qualification, we also successfully completed an accelerated wet ageing programme to demonstrate the design life of the new cables. The wet age testing programme was performed using full size 66kV cables in saline water rather than scale model cable samples tested in tap water, which tends to standard practice in medium voltage wet-ageing test protocols. Our accelerated wet ageing tests therefore simulate more realistic offshore conditions which is an advanced development within the industry.

The development programme also involved collaborations with the full supply chain, developers and stakeholders, including working closely with the Department for Energy and Climate Change and the Offshore Wind Accelerator. Our customers benefit from innovation without compromise – we constantly strive to develop the best possible solution for our clients while ensuring that our standards for reliability, quality and safety are met every time.

This new technology also has potential within the offshore oil and gas industry as subsea power transmission requirements increase to oil and gas fields. The subsea factory of the future will continue to push technologies to higher voltages and our 72.5kV cable is an enabling technology to support developers leading in this field.

In July, we held a customer event where we provided an overview of the high-voltage and full-scale wet-age testing, cable splicing, joints and connectors and thermal analysis techniques that are performed in-house. This helped a number of our customers to consider 66kV cables for their next offshore wind farm projects. We were proud to demonstrate the quality and reliability of our cable technology, as the only supplier of inter-array cables with zero failures in service.

Our collaborations and industry leading test regime provides confidence to customers that our 66kV (72.5kV) cables are fully qualified to meet the future needs of the energy industry.

For more than 20 years, JDR has built its success on technical expertise and reliability. Every market we enter, every customer we serve, and every project we deliver benefits from our dedication to technical quality, service and support.

For Further information, please get in touch