Cable wrapping

Details Cable wrapping Cable wrapping

1995-05-17

1998-10-06

Kincaid, Kristine L.

Electricity: conductors and insulators

Anti-inductive structures

Conductor transposition

174106R, 174124R, H01B 718, H01B 1106

Patent

active

058179747

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

This invention relates to the manufacture of cables and more specifically to the use of electrically conductive cable wrapping in the manufacture of cables.
The use of conductive wrappings in cables is known. In the manufacture of power cables, conductive wrapping is used in the screen range, in order to provide for a good electrical contact between the core screen, the metal screen and the metal water barrier, if any is present. In this type of cable wrapping it is only important that volume conductivity is provided in the wrapping.
In signal cable, conductive cable wrapping is used to obtain `shielding` in the cable, i.e. a shielding from electromagnetic interference from the outside to the inside and/or from the inside to the outside.
The nature and structure of such types of cables are different, which is also apparent from the requirements imposed on the cable wrapping. For power cable, there is a need for thick wrapping which swells strongly and is properly conductive. For signal cable, on the other hand, it may suffice to use a wrapping that does not swell quite so strongly and which is preferably thin.
Well known are types of cable wrapping which are built up from a fibrous web (non-woven) which has been impregnated with conductive carbon black. In particular in the case where the wrapping must impart to the cable not only conductive properties but also longitudinal water impermeability, a problem arises in that the conductive properties sometimes are exhibited insufficiently.
A disadvantage of the use of conductive carbon black is that carbon black is noble in comparison with the metals which are present in cables. This means that galvanic corrosion of conductors and/or the screen can arise, which is undesirable.


SUMMARY OF THE INVENTION

The object of the invention is to provide a conductive cable wrapping, which may optionally comprise a water-swellable material, to which wrapping have been imparted in a simple manner suitable conductive properties, such as volume conductance and/or shielding, while a number of disadvantages of the prior art do not arise or arise to a minor extent only.
The invention is based inter alia on the surprising insight that it is possible to provide a network by which electrical conduction and/or shielding are obtained in a cable by the use of conductive fibers, for instance in the form of a blend of non-conductive fibers and conductive fibers, optionally in combination with a water-swellable material, or by an assembly of a conductive and a non-conductive cloth which have been bonded onto each other.
The invention accordingly relates inter alia to the use of a conductive fiber cloth comprising at least one conductive fibrous material, as cable wrapping for providing conductance, shielding, or a combination of the two in a cable.
Surprisingly, it has been found that such a conductive cloth is highly suitable for imparting conductive and/or shielding properties to power or signal cable. By the use of conductive fibers in the wrapping, the undesired galvanic corrosion caused by carbon black does not arise or arises to a minor extent only, since the conductive wrapping comprises metal fibers which are not nobler than the conductor and/or the shield, so that the conductor is not affected by galvanic corrosion.
According to the invention, a number of embodiments of the (conductive) cable wrapping can be used, depending on the nature of the use, i.e. for power or signal cable, comprising swellable material or not, and comprising nonconductive, optionally reinforcing, fibers or not.


BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a transverse cross-sectional view of a cable provided with a wrapping in accordance with principles of the present invention.


DETAILED DESCRIPTION

In a first embodiment, the invention relates to the use of a fiber cloth comprising at least one non-conductive or substantially non-conductive, optionally reinforcing, fiber, at least one type of conductive fibrous material and a water-swellable material provided on and/or

REFERENCES:
patent: 4318719 (1982-03-01), Kato et al.
patent: 4595793 (1986-06-01), Arroyo et al.
patent: 4749625 (1988-06-01), Obayashi et al.
patent: 4761520 (1988-08-01), Wade, Jr. et al.
patent: 4822950 (1989-04-01), Schmitt
patent: 4957883 (1990-09-01), Kobayashi et al.
patent: 5010209 (1991-04-01), Marciano-Agostinelli et al.

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