REWARD - Reliability of eco-friendly cables in future power grids

The large-scale electrification of society and the increasing use of renewable energy place higher demands on the cable network. To achieve increased transmission capacity at lower costs, combined with upcoming requirements for a circular economy and environmentally friendly materials, cables with polypropylene-based thermoplastic materials (PP-TP) insulation can be a good alternative to cables with cross-linked polyethylene (PEX) currently in use. PP-TP can be melted down, requires less energy, generates fewer CO₂ emissions during production, and has a shorter production time.

For the past 50 years, only PEX-insulated cables have been approved for installation according to the Norwegian standard NEK HD 620 S2, but it is now being revised to allow the use of thermoplastic insulation materials.

Research results from REWARD will provide a better foundation for ensuring the long lifespan and safe utilization of PP-TP cables, avoiding many of the early failures observed after the installation of first- and second-generation PEX cables.

As limited-service experience is available, especially in colder climate, there are significant knowledge and technology gaps that need to be addressed prior to large-scale installation of PP-TP cables.

Main objective:

Develop new knowledge about what limits the lifespan of cables with PP-TP insulation and about test methods which can be used to ensure high reliability during operations.

REWARD aims to:

• Examine how mechanically induced weaknesses effects the electrical properties of PP-TP as an insulation material.
• Establish the impact of introduced defects on the service lifetime.
• Determine at which conditions water trees may grow in PP-TP insulation and develop analysis methods
• Provide reliable methodologies for wet ageing test of PP-TP cables

In REWARD, the main focus will be on the use of PP-TP as an insulation system in medium-voltage and high-voltage AC cables (12-145 kV), but it will also investigate properties relevant at higher voltages (=145 kV) for cables with both dry and wet design.