Multilayer cable - has layers with same lay and structured lay lengths for equal shift if the cable is twisted

摘要

The multilayer cable, for electrical conductors and/or optic fibres, is twisted with the same lay in the separate layers. The lay lengths match each other so that, on an applied torsion to the cable by an angle, the separate layers shift by generally the same amt., without altering the mean twisted dia. of each layer. Pref. the layer is twisted to give values of dl and sl with sl = so X dl2/do2. The mantle is of an elastic material in two layers (3,4) where the inner layer (4) is a buffer of an easily compressible material and the second layer is extruded over it. The outer mantle (3) is of PVC with a Shore hardness of about 80, or rubber or PUR. A lubricant is applied to the conductive cores to allow them to slide against each other. Where the cable carries a mixture of electrical conductors and optic fibres, the components to be twisted have the same dia.. ADVANTAGE - The cable has a long life as it is undamaged by twisting.