EP1916674A2

EP1916674A2 - Low load-loss electric cable for aeronautical use

Info

Publication number: EP1916674A2
Application number: EP07018931A
Authority: EP
Inventors: Luigi Bussetti
Original assignee: Intercond SpA
Current assignee: NEXANS INTERCABLO S.P.A.
Priority date: 2006-10-23
Filing date: 2007-09-26
Publication date: 2008-04-30
Also published as: EP1916674A3; ITMI20062027A1

Abstract

The present invention relates to a low load-loss electric cable, particularly for aeronautical, civil and industrial uses, which comprises a single conductor for phase.

The cable conductors are circumferentially distributed and alternately arranged with the earth conductors.

Each said conductor is electrically insulated and arranged inside a cable insulating sheath.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a low load loss electric cable, specifically designed for aeronautical, civil and industrial uses.
As is known, electric cables used in aeronautical applications are subjected to load losses which are substantially due to the resistivity of the material forming the conductor and its inductive reactance.
To allow this voltage loss to be held as low as possible, the cable makers have already made electric cables having very low inductive reactances, by splitting into two parts the power supply phases, thereby substantially providing an electric cable in which for each phase are provided two electric conductors, which are sequentially and circumferentially arranged about a central cable providing the neutral conductor.
Thus, is provided a "parallel" connection of inductances, allowing to greatly reduce the inductive reactance value, to cause the voltage loss or drop to be held within acceptable values.
The thus made electric cable has overcome and/or alleviated difficulties related to transmission problems: however, since the cable is used for a movable installation, i.e. a non-fixed assembling, the above disclosed embodiments has been found to be affected by several drawbacks occurring in a practically use of the cable, since the stiffness of the cable is greatly increased, and moreover the thus designed cable has a very low strength against alternating foldings.
Moreover, as the cable is taken from the cable coil, the pulling force is mainly concentrated on the cable central element which, as it is wound about a winding mandrel having a diameter of 350 mm, tends to horizontally exit its original seat.
Furthermore, the above mentioned stress causes the cable to be early worn, together with its terminal contacts as applied to the cable itself.

SUMMARY OF THE INVENTION

Accordingly, the aim of the present invention is to overcome the above mentioned drawbacks, by providing an electric cable with a low load loss, specifically for aeronautical use, allowing to reduce to a minimum the voltage drop or loss, owing to a very low value of the electric resistance and inductive reactance thereof.
Within the scope of the above mentioned aim, a main object of the invention is to provide such an electric cable having a very low skin effect, that is a very low trend for the current passing therethrough to be distributed on the periphery of the cable conductor, to leave practically unused the central part thereof.
Yet another object of the present invention is to provide such an electric cable improving the amperometric capability per phase and which is provided with phases of the same length.
Yet another object of the present invention is to provide such an electric cable which has a great flexibility and allows to distribute the pulling forces occurring during its use through all the cable components, and which, moreover, can be bent according to a much less bending radius.
Yet another object of the present invention is to provide such an electric cable which is very advantageous from a mere economic standpoint and which, moreover, has a very low weight.
According to one aspect of the present invention, the above mentioned aim and objects, as well as yet other objects, which will become more apparent hereinafter, are achieved by an electric cable with low load losses, specifically for aeronautical use, characterized in that said electric cable comprises a single cable conductor per phase, said conductors being circumferentially distributed and alternated with earth conductors, each said conductor being electrically insulated and arranged inside an insulating sheath of said electric cable.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will become more apparent hereinafter from the following detailed disclosure of a preferred, though not exclusive, embodiment of an electric cable with low load losses, specifically designed for aeronautical use, and which is illustrated, by way of an indicative, but not limitative, example in the accompanying drawings, where:

Figure 1 is a cross-sectional view showing the electric cable according to the invention; and
Figure 2 is a detail view showing a detail of a phase conductor, constituting a part of the electric cable shown in figure 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to the number references of the above mentioned figures, the low load loss electric cable, specifically designed for aeronautical use, which has been generally indicated by the reference number 10, comprises a plurality of insulated phase conductors 1 and, more specifically, a conductor 1 for each phase.
As shown, said phase conductors 1 are circumferentially distributed and alternated with the neutral conductors, which are generally indicated by the reference number 3.
Thus, the subject cable comprises three phase conductors 1, which are circumferentially distributed, in addition to three insulated earth conductors 3 and several assemblies of insulated signal conductors 4.
A main feature of the invention is that each phase conductor 1 is made by using a set of electric wires, indicated by the reference number 9, and constituting a cable beam, as suitably insulated by an insulating material cable sheath 11.
More specifically, each phase conductor 1 comprises a reinforcement central cable 12, and an insulating element 5, comprising an outer insulating sheath, which can be formed in multiple layers or in any other per se known manners.
Thus, the use of conductors made of a plurality of sets of wires 9, which are individually insulated, allows to drastically reduce the cable skin effect, thereby the conductor will be not overheated, thereby achieving a larger amperometric current capability for phase.
Another important aspect of the invention is that the cable 1, which is made by three phase conductors 1 which are circumferentially and evenly distributed, and three earth conductors 3, allows to better distribute the pulling efforts during its use, since said efforts or forces will be evenly distributed through each phase conductor 1, which, as stated, comprises a respective reinforcement element 12.
Another important aspect of the invention is that the conductor cross section of 50 mm², provides operating properties like those of a phase of 95 mm², with a consequent less weight of the finished cable.
It should be moreover pointed out that the subject low load loss electric cable 10 comprises neutral conductors 3, signal conductors 4 and a suitable insulating pattern or member 5.
Said cable comprises moreover holding strips 6, inner sheath elements and reinforcement braid 7, and an outer sheath 8.
Thus, the cable according to the invention provides a "parallel" arrangement of n conductor cable elements, with the following advantages:

1) Transmission advantages:
- 2.2) A less voltage loss or drop, due to the very low electric resistance and inductive reactance values.
- 2.3) A less skin effect and accordingly a less overheating of the conductor.
- 2.4) A larger amperometric current capability per phase,
- 2.5) An equal or like length of the individual phases, with a consequent very even voltage thereon.
2) Dynamic application advantages:
- 2.1) A complete lacking of the central element.
- 2.2) A distributing of the pulling forces during the cable use, which pulling forces or efforts are distributed through the overall elements forming the cable core.
- 2.3) A greater flexibility.
- 2.4) The subject cable can be bent through a bending radius of 200 mm.
- 2.5) The subject cable can be easily connected:
- 2.6) A great economic advantage: actually, as stated, the conductor cross section of 50 mm² provide operating properties like those of a phase of 95 mm².
- 2.7) A less weight of the finished cable.

From the above disclosure it should be apparent that the invention fully achieves the indented aim and objects.
In particular, the fact is to be pointed out that the cable 10, since it is made of conductors 1 comprising a plurality of insulated wires, allows to drastically reduce the cable load losses, and to allow all the desired connections to be easily and quickly made.
The invention, as disclosed, is susceptible to several modifications and variations, all of which will come within the scope of the invention.
It should be apparent that the inventive cable may also be used for other civil and industrial applications.
Moreover, all the disclosed details of the subject cable can be replaced by other technically equivalent elements.

Claims

A low load loss electric cable, specifically for aeronautical use, characterized in that said electric cable comprises a single cable conductor per phase, said conductors being circumferentially distributed and alternated with earth conductors, each said conductor being electrically insulated and arranged inside an insulating sheath of said electric cable.
An electric cable, according to the preceding claim, characterized in that each said conductor set is made of a plurality of adjoining electric wires.
An electric cable, according to the preceding claims, characterized in that said electric wire sets are insulated from one another.
An electric cable, according to one or more of the preceding claims, characterized in that said phase conductors have a substantially equal cross section.
An electric cable, according to one or more of the preceding claims, characterized in that said electric cable comprises a central reinforcement element and an insulated sheath encompassing the phase conductor.
A low load loss electric cable, according to claim 1, characterized in that said electric cable comprises three phase conductors including a central reinforcement and further including single cable beams having an insulating material sheath and a dielectric material outer sheath.
A low load loss electric cable, according to claim 1, characterized in that said electric cable comprises a set of neutral conductors arranged between the phase conductors and including respective insulating sheaths.
A low load loss electric cable, according to one or more of the preceding claims, characterized in that said electric cable comprises a plurality of spaced signal conductors.
A low load loss electric cable, according to one or more of the preceding claims, characterized in that each said phase conductor comprises a suitable insulation.
A low load loss electric cable, according to one or more of the preceding claims, characterized in that said electric cable comprises an inner sheath having a reinforcement braid.
A low load loss electric cable, according to one or more of the preceding claims, characterized in that said electric cable comprises an outer sheath.
A low load loss electric cable, according to one or more of the preceding claims, characterized in that said electric cable, in addition to being adapted for use for aeronautic applications, can also be used for civil and industrial applications, and substantially as broadly disclosed and illustrated in the preceding disclosure and in the figures of the accompanying drawings.