A new high voltage XLPE alternative from Prysmian

In 2011 Prysmian launched P-Laser, its medium voltage distribution grid cable solution, on the international market. The aim was to take advantage of the perceived need for an environmentally- friendly product that could meet the increasing demand for distribution cables to accommodate the influx of renewables and the consequent grid reorganisation. It was promoted as the first high-performance, eco- sustainable cable for electrical grids.

The basis for this claim was that it was manufactured entirely from raw materials that were recyclable, while exhibiting improved performance. P-Laser could therefore help to reduce the environmental impact of electrical grids while increasing their efficiency and transmission capacity.

At the time of the launch P-Laser had received IMQ certification in Italy and had also been approved and adopted by Italian utilities. Since that time, as R&D on the product continued, its applicability has widened as it has swiftly risen up the voltage rankings. To date more than 17 000 km of the cable has been produced and installed in Europe.

First HV grid

In 2013 Prysmian contracted with Italian utility Terna to implement the first high voltage grid using the new cable. It took the form of a 150kV, 5 km link in Lacchiarella, near Milan and was said to represent a radical step in the reorganisation of the high voltage transmission grid in the south-west area of Milan. It would employ a Prycam partial discharge monitoring system to allow connections to be optimised.

Then in April this year Prysmian announced the successful development and testing of a 525 kV version of the P-Laser cable system for HVDC applications. This was in fact the first recyclable HVDC cable.

To 600 kV and beyond

At end-September this year Prysmian announced that it was ready to launch the most powerful cable solution ever for power transmission grids, one that would be fully recyclable and allow a cost reduction of up to 30% per transmitted MW.

This was the newest version of its P-Laser product, and Prysmian was announcing its successful development and testing at 600 kV and with a capacity of 3.5 GW in a bipole configuration for HVDC applications.

Prysmian believes that this technology is the most advanced and innovative that uses an in-house developed thermoplastic conductor material. This is known as HPTE (high performance thermoplastic elastomer) and that permits a more efficient cable production, where manufacture is performed in a single and continuous process, with lower environmental impact than traditional XLPE. A key feature of this insulation technology is that, compared to XLPE, it does not require a chemical reaction during manufacture to achieve the material properties required for the long term electrical integrity of HVDC insulation systems. This feature gives the additional benefit of shorter production times and results in both reduced energy consumption as well as lower greenhouse gas emissions. The system is said to be fully compatible with existing cable and accessory technologies and provides a better electrical performance and a higher reliability when compared with XLPE-insulated cables.

From an efficiency point of view, P-Laser technology allows grid operators to work at temperatures above the 90°C typical of conventional XLPE technology. This higher thermal performance allows an increase of the power transmission for the same conductor section, or a longer cable life at the same temperature, but above all it allows higher capability. This is particularly important in the event of emergencies such as grid congestion or an N-1 condition – disconnection because of malfunction or maintenance of an adjacent line.

Eco-friendly

The cable manufacturing process uses thermoplastic materials and it is totally eco-friendly – 500kg of high-quality plastics can be recovered from every kilometre of cable.

Its production process also benefits from a ‘zero-gas technology’ that reduces carbon dioxide emissions by around 1 tonne/km. And the use of thermoplastic means that degassing during production is no longer required and the possibility of uninterrupted, single-line production can significantly streamline the supply chain.