Why stranded wires?
Stranded wires consist of many thin, individually insulated wires that are twisted or braided together. This construction offers decisive advantages over solid conductors:
- Reduction of the skin effect: At high frequencies, as occur in the power electronics of electric motors, the current flow is concentrated on the surface of the conductor due to the skin effect (current displacement). This increases the resistance, as only a narrow conductor area is available on the outside for the current flow. This also increases the losses. Stranded wires reduce the skin effect, as the individual wires have a smaller diameter and therefore offer a significantly larger surface area overall.
- The proximity effect, also known as the neighborhood effect, is a phenomenon that occurs in high-current conductors when they are arranged in close proximity to each other and have alternating current flowing through them. The reason for the effect is the induced magnetic fields of the neighboring conductors. Without countermeasures, the proximity effect leads to an uneven current distribution in the conductor cross-section, increased losses and, in extreme cases, overheating. The countermeasure is to use stranded conductors in which the individual wires are twisted or braided. This reduces the neighborhood effect and thus leads to lower losses in high-current cables
- Flexibility: Stranded wires are significantly more flexible than solid conductors with a comparable cross-section. This is particularly important in applications where movement or vibrations occur, such as in electric motors in vehicles.
Insulation for stranded wires
In stranded conductors, the individual, fine strands (small-diameter enameled copper wires) are insulated from each other by a layer of insulating varnish. However, as with any other cable, it is also necessary to have good insulation around the stranded conductor as mechanical protection and insulation from the environment. The use of insulating adhesive tapes from CMC Klebetechnik is particularly advantageous in highly stressed areas with flexibility requirements or with compression stranded wires.
The adhesive fixing prevents the overlaps from shifting in relation to each other (air gap of the insulation) in bending areas and increases the mechanical resistance to friction and chafing. By selecting the right insulation film (e.g. polyester, Kapton® or PTFE), the cable insulation can be adapted to the requirements of the application.
CMC Klebetechnik supplies the adhesive tapes in various thicknesses and in the individually required width. For applications subject to particularly high temperatures, suitable polyimide films can be supplied as well as adhesives that can withstand high temperatures of up to 200°C.
Conclusion
Due to their special properties, stranded conductors are the ideal choice for high-current and high-frequency applications, especially in electromobility. They reduce the skin effect and eddy current losses, offer a high degree of flexibility and thus enable more efficient and reliable electrical systems. The choice of suitable insulation tape from CMC Klebetechnik is crucial for the durability and safety of the stranded wires.
Kontakt:
Kontaktieren Sie direkt Ihren Ansprechpartner oder senden Sie uns eine Mail an:info@cmc.de
Stranded wires in electromobility and their insulation with adhesive tapes