Bending of helically twisted cables under variable ... - Pfisterer

1. Introduction
1.1. Status and problem definition
1
This project deals with the bending characteristics of tensioned multi-layer helically twisted cables. The
cables under investigation were cables comprising of a straight wire core and concentric layers of
helically twisted round wires, alternately right and left lay, Fig. 1.1.
Fig. 1.1 Basic construction of a helically twisted cable
Helically twisted steel cables have many applications for conveyance, as components of a variety of
constructions.
So-called stranded conductors used in overhead lines for power transmission are a special application
of helically twisted cables. In most cases, these cables comprise of two materials, a so-called core (i.e.
the core steel wire and one or two steel wire layers), mainly for absorbing the mechanical loads acting
on the cable, plus a number of helical layers of aluminium wires to carry the current. In addition, a single
component overhead conductor made of AlMgSi alloys, the so-called Aldrey conductor, is often found in
Switzerland, with very good results under the local operating conditions.
The importance of these overhead conductors for reliable operation of the electrical transmission
network is well known. They are utilised in high voltage transmission lines worldwide, for thousands of
kilometres.