Not just for protecting against short circuits
Conductors require electrical insulation. In single-core wires, this insulation acts as touch protection. In multi-core wires, it prevents current flowing from one conductor to another and causing a short circuit. You may have already experienced what happens when this insulation fails. When putting away old hair dryers or irons, for example, we often wrap the power cord around the handle. After being wrapped and twisted like this thousands of times, the sheath breaks followed by the insulation, usually at the point where the cable enters the housing. A flash of electricity then shoots out of the cable and the lights in the house go out with a loud bang after the fuse hopefully trips. If unsuitable cables are used in industrial applications, not only can these incidents happen more frequently, but the consequences can be severe, such as hours of production downtime in a factory.
Insulation must do more than just provide protection, however. In data transfer cables like ETHERLINE®, the insulation can determine the transmission quality or, more precisely, the signal losses during transmission. This is because the electrical signal interacts with the plastic and gives off energy. This causes the plastic to heat up slightly and the signal weakens until it causes dropouts. The most important factor here is the dielectric constant of the plastic, which should be as low as possible. Polyethylene and polypropylene are plastics that offer a low dielectric constant. This value can be reduced further by using nitrogen to turn the plastic into a foam when it is extruded onto the conductor. Lapp subsidiary CEAM Cavi Speciali, based in the Italian town of Monselice, produces its high-quality data cables in a complex process. Here, up to three layers are applied simultaneously from three extruders, while the middle layer is foamed. These cables enable high data transfer rates across long distances, and are also slightly thinner than conventional cables. This is because the foam layer offers better insulation properties, and can therefore be thinner.