Modifying Silicone Rubber
Electrically-conducting silicone elastomers
from the POWERSIL® product line ensure a
continuous flow of current through underground and undersea cables.
The increased use of renewable energy sources is resulting in the decentralization of power generation. Wind turbines, solar panels and biogas power plants at many different locations produce electricity that must be hooked up to the power supply network. Laying electrical cable underground or – as is the case with offshore wind farms – at the bottom of the sea is much more complicated and expensive than above ground. Thus, to be economical, these cables need to remain functional for at least several decades.
Medium-Voltage Cable Sleeves Made from POWERSIL®
Medium-Voltage Cable Sleeves Made from POWERSIL®
Dr. Jens Lambrecht, a technical service manager at WACKER’s Industrial Solutions business team, explains why that is so difficult: “Simple insulation cannot cope with medium voltages between the outer and inner conductors in cables, which can range from 6,000 to 30,000 volts.” The metal cores need to be jacketed in both electrically insulating and conducting materials to avoid partial discharges that would otherwise occur inside a cable sleeve or at end pieces, such as cable plugs. Not only are these discharges dangerous, they can severely damage the component.
This is where the POWERSIL®range of silicone elastomers come into play. These have been modified with special carbon black particles to render them electrically conductive. The tiny carbon particles form percolation networks – three-dimensional electrically conducting structures. They ensure that cable plugs are scoop-proof, that cable sleeves are adequately shielded, and that there is a reliable contact between the metal parts.
Medium-voltage cables can only be transported in defined lengths.
Medium-voltage cables can only be transported in defined lengths.
WACKER collaborates with the Zittau/Görlitz University of Applied Sciences to evaluate these materials thoroughly. In numerous tests over the last four years, the engineers in Zittau discovered that silicone elastomers modified with carbon black can withstand permanent loading with certain current densities without any change in resistance. And, for short periods of time, the material will tolerate higher values than those experienced in long-term exposure.
Thanks to these results, WACKER researchers can now provide manufacturers with sound advice on cable accessories. The scientists were also interested in finding out the materials’ limitations. “Even the very best material will be destroyed if it isn’t used correctly and appropriately,” notes Professor Roland Bärsch from the university’s department of electrical engineering and IT. It is crucial that the assembly technology be as rugged, safe and simple as possible. “It is not the cables themselves which are the weak point, but rather the connectors,” says Bärsch.
In order for these interfaces to be especially durable and rugged, the materials must be of the appropriate quality. POWERSIL®silicone elastomers provide the needed long-term quality and reliability – and ensure that underground and undersea cables keep transmitting power faultlessly decades after they were laid.
The Fascination of Chemistry – WACKER’s Audio Magazine
