Protective sheath for a protected harness

Abstract

The invention relates to an aircraft electrical cable (9) comprising a sheath for protection against electric arcs, said protective sheath comprising: a first casing (1) positioned around the electrical cable (9) and configured to electrically insulate said electrical cable (9) by absorbing the energy of an electric arc originating from a defective portion of the electrical cable (9) and encasing said defective portion; a second casing (2) positioned around the first casing (1), said second casing (2) being configured to contain the first casing (1) and to electrically insulate the first casing (1) by absorbing a residual energy of the electric arc having passed through the first casing (1).

Description

[0001] DESCRIPTION

[0002] TITLE: PROTECTIVE COVER FOR PROTECTED HARNESS

[0003] Scope of the invention

[0004] The present invention relates to the field of aircraft, and more particularly to electrical installations within these aircraft.

[0005] More specifically, the present invention relates to a protective sheath for a bundle of electrical cables configured to protect such electrical cables against electrical arcs.

[0006] Such an invention is particularly applicable in the aeronautical field, but can also be applied in other industrial fields such as the nuclear field, the railway field, the automotive field, and the medical field.

[0007] Prior art

[0008] Arc flash protection in aircraft is a critical concern for ensuring flight safety. Arc flashes can be caused by various factors, such as insulation faults, power surges, or wiring faults. These arc flashes can potentially lead to fires or other serious damage.

[0009] Even if the creation of an electric arc triggers means of cutting off the electrical circuit, there remains a residual time between the creation of the electric arc and the triggering of these means which remains a problem for aircraft manufacturers.

[0010] Solutions exist to protect signal cables against electrical arcs from the outside, mainly in the form of sheaths placed around a cable, or a bundle of cables that one wishes to protect against such external aggressions.

[0011] These sheaths can, for example, be open textile sheaths, particularly in the aeronautical sector. They can also be self-closing tapes, which allow for the placement of cable harnesses while minimizing stress. They are typically made from materials resistant to extreme temperatures and shape-memory thermoplastic polymers to maintain the sheath's shape regardless of the operating conditions.

[0012] However, due to their open structure, the configuration of these sheaths allows protection against electrical arcs coming from the outside but does not allow the confinement of an electrical arc that would occur inside the bundle of cables that this sheath protects.

[0013] While these open sheaths are sufficient to protect against current voltage levels, they are not robust enough to contain an electrical arc at significantly higher voltage levels. Indeed, the current flowing in current aircraft does not exceed 115 volts at 30 amps, but in the future, it could exceed 800 volts at 500 amps in aircraft with a high electrical component. The electrical arcs that can occur in these new electrical configurations will therefore be more powerful, making it necessary to contain these arcs to protect the entire surrounding environment while the active protection devices, also known as circuit breakers, are activated.

[0014] Description of the invention

[0015] The invention aims to remedy at least in part the aforementioned drawbacks relating to prior art techniques.

[0016] To this end, the invention relates to an arc flash protection sheath for electrical cable, particularly aircraft cable, said protection sheath comprising: a first envelope configured to be positioned around said electrical cable so as to electrically insulate said electrical cable by absorbing the energy of an electric arc coming from a defective portion of said electrical cable and by wrapping said defective portion; a second envelope positioned around said first envelope, said second envelope being configured to contain said first envelope and to electrically insulate said first envelope by absorbing residual energy from said electric arc having passed through said first envelope.

[0017] Thus, the solution proposes an approach that allows us to resolve, at least in part, some of the drawbacks of the previous art.

[0018] In particular, such a sheath has the advantage of confining an electric arc that would occur inside an electrical cable so that it does not propagate to other components of the electrical installation.

[0019] In addition, by implementing a first and second sheath, the integrity and potential degradation of nearby components are also protected by limiting the spread of the electric arc, but also of parts of the first sheath that could detach from the electrical cable in the event of melting of this sheath.

[0020] According to a particular aspect of at least one embodiment of the invention, said first envelope is made at least partly from polymer.

[0021] According to a particular aspect of at least one embodiment of the invention, said polymer exhibits a temperature resistance of at least -55°C to 240°C and a thermal conductivity greater than or equal to 0.1 W / m². -1 K -1 According to a particular aspect of at least one embodiment of the invention, said polymer is chosen from PTFE or PEEK.

[0022] According to a particular aspect of at least one embodiment of the invention, said first envelope is convoluted and includes at least one drain provided on its surface so as to evacuate condensation formed on said electrical cable.

[0023] According to a particular aspect of at least one embodiment of the invention, said first envelope is made from braided polymer.

[0024] According to a particular aspect of at least one embodiment of the invention, said second envelope is made at least from a layer of braided textile fiber.

[0025] According to a particular aspect of at least one embodiment of the invention, said second envelope has a temperature resistance between -55°C and 240°C.

[0026] According to a particular aspect of at least one embodiment of the invention, said braided textile fiber is selected from ParaAramid, MetaAramid, or Basalt.

[0027] According to a particular aspect of at least one embodiment of the invention, said second envelope has a toughness greater than or equal to 6 cN / dTex.

[0028] According to a particular aspect of at least one embodiment of the invention, the first envelope and / or the second envelope is non-flammable and / or self-extinguishing and / or does not drip.

[0029] According to a particular aspect of at least one embodiment of the invention, the protective sheath further comprises a third envelope positioned around said second envelope, said third envelope being configured to contain said second envelope and to electrically insulate said second envelope by absorbing residual energy from said electric arc having passed through said second envelope.

[0030] According to a particular aspect of at least one embodiment of the invention, the third envelope is made of the same material as the second envelope.

[0031] According to another particular aspect of at least one embodiment of the invention, the third cover is made of a different textile material than the second cover.

[0032] The invention also relates to a protected harness comprising at least one electrical cable and a protective sheath according to one of the aforementioned embodiments, said sheath being positioned around said electrical cable.

[0033] The invention further relates to an aircraft electrical installation employing protected harnesses according to the aforementioned embodiment.

[0034] Presentation of the figures The invention, as well as its various advantages, will be more easily understood in light of the following description of an illustrative and non-limiting embodiment thereof, and the accompanying drawings, among which:

[0035] [Fig. 1] illustrates a schematic side view of a protected harness according to one embodiment of the invention, and

[0036] [Fig. 2] illustrates a schematic cross-sectional view of a protected harness according to another embodiment.

[0037] Detailed description of an embodiment of the invention

[0038] The invention is based on the implementation of a protective sheath that confines an electric arc that would occur inside the protective sheath so that it does not propagate to other components of the electrical installation and so that any debris from the electrical cable thus damaged does not contaminate other nearby components.

[0039] The invention also relies on the implementation of a protected harness comprising at least one electrical cable and a protective sheath.

[0040] It should be noted that, according to one aspect of an embodiment of the invention, the sheath can have a diameter as close as possible to the harness to be protected in order to avoid space and therefore air.

[0041] Figure 1 illustrates an embodiment in which the protected harness 5 includes an electrical cable 9 while Figure 2 illustrates an embodiment in which the protected harness 5 includes several electrical cables.

[0042] Such a solution is particularly well-suited to aircraft electrical installations. Indeed, with the advent of hybridization and the electrification of propulsion systems in aeronautics, confining electrical arcs within high-power connectors is a priority to guarantee the safety and integrity of the aircraft environment's installations.

[0043] Such a solution could also be implemented in other industrial sectors, such as nuclear, rail, automotive, or medical. The solution described can be implemented in both pressurized and unpressurized environments.

[0044] The solution described also has the advantage of being usable in areas reaching relatively high temperatures.

[0045] Two embodiments of the invention are now presented in relation to Figures 1 and 2. As illustrated, the protective sheath 10 against electric arcs, whether generated from the inside or from the outside, comprises: a first sheath 1 configured to be positioned around the electrical cable 9 so as to electrically insulate this electrical cable 9 by absorbing the energy of an electric arc originating from a defective portion of the electrical cable 9 and by enveloping the defective portion; a second sheath 2 positioned around the first sheath 1, the second sheath 2 being configured to contain the first sheath 1 and to electrically insulate the first sheath 1 by absorbing residual energy from the electric arc having passed through the first sheath 1.

[0046] In other words, the first sheath allows at least a major part of the energy of the electric arc, or even all of it, and also acts as a backup insulator by melting and covering the defective portion(s) of the electrical cable 9 where the electric arc has formed.

[0047] In this embodiment, the first envelope 1 is made at least partly from polymer. The polymer is particularly effective at containing the electric arc by degrading under the effect of the heat generated by the electric arc.

[0048] This polymer is chosen here so that its temperature resistance is between -55°C and 240°C and its thermal conductivity is greater than or equal to 0.1 Wm -1 K -1 .

[0049] Therefore, and in view of the characteristics of the polymer in this embodiment, the polymer is chosen here from PTFE and PEEK.

[0050] It should be noted that preferably this first envelope 1 is non-flammable and / or self-extinguishing and / or does not drip.

[0051] According to a first alternative, the first envelope 1 can be convoluted and can include at least one drain provided on its surface so as to evacuate condensation formed on the electrical cable 9.

[0052] One advantage of a convoluted first layer is its ability to contain high-power electrical arcs for relatively long periods. It also allows it to adapt to the curves of a protected harness and prevents the first layer from bunching up in the curved sections of the harness.

[0053] Indeed, the folds of an envelope may damage the electrical cable and thus increase the risk of malfunction.

[0054] According to a second alternative, the first envelope 1 can be made from braided polymer.

[0055] One advantage of a first layer made of braided polymer is that it proves to be relatively flexible.

[0056] As for the second jacket, it contains the residue from the first molten jacket and also enhances the absorption of the electric arc's energy by absorbing energy that would not have been absorbed by the first jacket. In this embodiment, this second jacket is made, at least, from a layer of braided textile fiber.

[0057] This at least one layer of braided fiber is chosen here so that the second layer 2 has a temperature resistance between -55°C and 240°C and a tenacity greater than or equal to 6 cN / dTex.

[0058] Therefore, and in view of the characteristics of the braided textile fiber of this embodiment, this braided textile fiber is chosen from ParaAmide, MetaAramid and Basalt.

[0059] It should be noted that preferably this second envelope 2 is non-flammable and / or self-extinguishing and / or does not drip.

[0060] The advantage of this embodiment, and in particular the coupled use of polymer and textile fiber in elements intended to protect against high-power electric arcs, is that it allows for a permanent and optimized confinement of the arc around the electrically conductive elements, in order to limit the propagation of electric arcs due to a fault in the electrical cable.

[0061] The embodiment illustrated in Figure 1 uses a protective sheath further comprising a third envelope 3 positioned around the second envelope 2

[0062] This third envelope 3 is configured to contain the second envelope 2 and to electrically isolate the second envelope 2 by absorbing residual energy from the electric arc that has passed through the second envelope 2.

[0063] Preferably, such a third envelope 3 is made of the same material as the second envelope 2.

Claims

DEMANDS

1. Protected harness (5) comprising at least one electrical cable (9) and an arc flash protection sheath for electrical cable (9), particularly aircraft cable, said protection sheath being positioned around said electrical cable (9) and comprising: a first sheath (1) positioned around said electrical cable (9) so as to electrically insulate said electrical cable (9) by absorbing the energy of an electric arc from a defective portion of said electrical cable (9) and by wrapping said defective portion; a second sheath (2) positioned around said first sheath (1), said second sheath (2) being configured to contain said first sheath (1) and to electrically insulate said first sheath (1) by absorbing residual energy from said electric arc having passed through said first sheath (1).

2. Protected harness (5) according to claim 1, characterized in that said first cover (1) is made at least partly from polymer.

3. A protected harness (5) according to the preceding claim, characterized in that said polymer has a temperature resistance between -55°C and 240°C and a thermal conductivity greater than or equal to 0.1 W / m². -1 K -1 .

4. Protected harness (5) according to the preceding claim, characterized in that said polymer is selected from PTFE or PEEK.

5. Protected harness (5) according to any one of claims 2 to 4, characterized in that said first sheath (1) is convoluted and includes at least one drain provided on its surface so as to evacuate condensation formed on said electrical cable (9).

6. Protected harness (5) according to any one of claims 2 to 4, characterized in that said first cover (1) is made from braided polymer.

7. Harness protected (5) according to any one of the preceding claims, characterized in that said second cover (2) is made at least from a layer of braided textile fibre.

8. Protected harness (5) according to the preceding claim, characterized in that said second cover (2) has a temperature resistance between -55°C and 240°C.

9. Harness protected (5) according to any one of claims 7 or 8, characterized in that said braided textile fibre is selected from ParaAramid, MetaAramid, or Basalt.

10. Protected harness (5) according to any one of claims 7 to 9, characterized in that said second sheath (2) has a toughness greater than or equal to 6 cN / dTex.

11. Harness protected (5) one of the preceding claims, characterized in that said first sheath (1) and / or said second sheath (2) is non-flammable and / or self-extinguishing and / or does not drip.

12. Protected harness (5) according to any one of the preceding claims, characterized in that it further comprises a third sheath (3) positioned around said second sheath (2), said third sheath (3) being configured to contain said second sheath (2) and to electrically insulate said second sheath (2) by absorbing residual energy from said electric arc having passed through said second sheath (2).

13. Protected harness (5) according to the preceding claim, characterized in that the third sheath (3) is made of the same material as the second sheath (2).

14. Aircraft electrical installation, characterized in that it implements protected harnesses according to one of the preceding claims.

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