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(11) | EP 4 586 282 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A STIFFENING CONDUCTOR ARRANGEMENT AND A METHOD FOR RESTRICTING MOVEMENT OF A CABLE OR BUSBAR |
| (57) The invention relates to a stiffening conductor arrangement (1) comprising a cable
(2) or busbar with an electric conductor (4). In order to obtain a structure in which
the arrangement is self-fortified by stiffening, and thereby enabling effortless installment
of the conductor arrangement with reduced space requirements, the conductor arrangement
(1) also comprises a layer of a dilatant material (5) covering at least a part of
the electric conductor (4).
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BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
[0001] This invention relates to a stiffening conductor arrangement and a method for restricting movement of a cable or busbar during a short circuit.
DESCRIPTION OF PRIOR ART
[0002] In relation to electric conductors used for high current power distribution, electromagnetic interactions are known to induce significant mechanical forces to the conductors during operation. These forces may cause damage to the conductor itself as well as structures surrounding it, and therefore need to be taken into account in the design of the conductor system. Said conductors typically include power cables and busbars used both as internal components of high current electric hardware and as power conductors between hardware units, and these usually need to be secured in place using dedicated fastening arrangements. The fastening arrangements need to be dimensioned according to estimated peak forces typically occurring in short circuit conditions.
[0003] The known fastening arrangements, typically comprising fastening brackets or clamps and fastening rails, require space in vicinity of the conductor and thereby limit the usability of the conductor system. The need for securing the conductor using several fastening components also adds to the complexity of the installment work and makes it relatively laborious. The fastening structures may also need to be changed after any incident, such as a short circuit situation inducing high mechanical forces to the conductor, further adding to the cost of maintenance of the conductor systems.
SUMMARY OF THE INVENTION
[0004] An object of the present invention is to solve the above-mentioned drawbacks and to provide a conductor arrangement enabling effortless installment with reduced space requirements. This object is achieved with a conductor arrangement according to independent claim 1 and a method according to independent claim 11.
[0005] By providing a stiffening conductor arrangement with a layer of a dilatant material covering at least a part of the electric conductor, it is possible to obtain a structure in which the arrangement is self-fortified by stiffening. This stiffening is obtained by use of the the dilatant material. The term 'dilatant' refers to a material exhibiting shear thickening behaviour, meaning that its viscosity increases with a rate of shear strain experienced by the material. Consequently, as a result of the shear forces affecting the dilatant material, the dilatant material becomes stiffer, which provides the cable or busbar with additional support against sudden movements which otherwise could result in damage to the cable, busbar or surrounding structures.
BRIEF DESCRIPTION OF DRAWINGS
[0007] In the following the present invention will be described in closer detail by way of example and with reference to the attached drawings, in which
Figure 1 illustrates a first embodiment of a stiffening conductor arrangement,
Figure 2 illustrates a cross-cut section of a second embodiment of the stiffening conductor arrangement,
Figure 3 illustrates a cross-cut section of a third embodiment of the stiffening conductor arrangement,
Figure 4 illustrates a cross-cut section of a fourth embodiment of the stiffening conductor arrangement,
Figure 5 illustrates a sleeve according to a fifth embodiment of the stiffening conductor arrangement,
Figure 6 illustrates a sixth embodiment of the stiffening conductor arrangement, and
Figure 7 illustrates a cross-cut section of a seventh embodiment of the stiffening conductor arrangement.
DESCRIPTION OF AT LEAST ONE EMBODIMENT
[0008] Figure 1 illustrates schematically a first embodiment of a stiffening conductor arrangement 1, wherein only a part of a cable 2 or a busbar comprised in the arrangement is illustrated. As seen in this example, the arrangement comprises the cable 2 or busbar having an electric conductor 4, wherein a layer of a dilatant material 5 is arranged to cover a part of the electric conductor 4. In other embodiments of the conductor arrangement, the layer of dilatant material 5 may also be arranged to cover the whole length of the conductor, or the arrangement may comprise several individually covered locations along the length of the electric conductor 4, for example. The layer of the dilatant material 5 may also cover the circumference of the conductor only partially at any of the locations to which it is provided. This makes it easy to retrofit the dilatant material 5 only to a part of a long cable or busbar, for instance. The term 'dilatant' refers to a material exhibiting shear thickening behaviour, meaning that its viscosity increases as a rate of shear strain experienced by the material increases.
[0009] With the arrangement as described, stiffness of the electric conductor 4 may be, along with the viscosity of the dilatant material 5, momentarily influenced by influencing the rate at which the electric conductor 4 is moved. More precisely, movement of the electric conductor by bending or twisting causes shear strain to be induced to the layer of dilatant material 5 covering it, said shear strain being a result of tensional or compressive forces being conveyed from the electric conductor to the dilatant material 5. By appropriately choosing the dilatant material 5, the electric conductor 4 may be arranged, for example, to experience significant stiffening only as a result of rapid movement of the electric conductor 4. Said rapid movement typically takes place during uncontrolled short circuit situations associated with applications of high current power distribution. Thereby, unwanted stiffening of the conductor arrangement 1 in other situations in which only moderate rate of movement takes place, for example during installation of the arrangement, may be avoided.
[0010] The embodiments of Figures 2 and 3 are very similar to the embodiment of Figure 1 and in the following, these embodiments will be explained mainly by pointing out the differences between these embodiments. Figures 2 and 3 illustrate schematically cross-cut sections according to a second and a third embodiment of the stiffening conductor arrangement, respectively, wherein the electric conductor 4 is covered with an electric insulator material 6. In the example of Figure 2, the electric insulator material 6 is arranged between the electric conductor 4 and the dilatant material 5, whereas in the example of Figure 3, the dilatant material 5 is arranged between the electric conductor 4 and the electric insulator material 6. In some embodiments, the dilatant material 5 may also act as an electric insulator, eliminating the need for a separate layer of the insulator material 6. The electric conductor 4 according to said examples may be, for example, an electric conductor used for high current power distribution in industrial applications.
[0011] In the arrangement according to Figure 2, the dilatant material 5 may be provided on a standardized electrically insulated conductor as a retrofit or as an integral layer during the manufacture of the electric conductor 4. On the other hand, in the arrangement according to Figure 3, the dilatant material 5 may be provided as an integral layer of the electric conductor 4 during the manufacture of the electric conductor 4 before the electric insulator material 6 is provided. In this case, the layer of insulator material 6 may also act as a binding structure for the dilatant material 5, allowing the dilatant material 5 in an unloaded state to have a very low viscosity and therefore a flowable form. In both arrangements, a layer of adhesive may be provided between the dilatant material 5 and the electric conductor 4, and/or between the dilatant material 5 and the electric insulator material 6 to secure them in place.
[0012] The embodiment of Figure 4 is very similar to the embodiments of Figures 1 - 3 and in the following, this embodiment will be explained mainly by pointing out the differences between these embodiments.
[0013] Figure 4 illustrates schematically a cross-cut section according to a fourth embodiment of the stiffening conductor arrangement, wherein the electric conductor 4 is covered with a support material 7 having a structure comprising enclosed cells 8. In this example, the dilatant material 5 is arranged within the enclosed cells 8 so that the support material 7 defines the extent to which the dilatant material covers the electric conductor 4. The enclosed cells 8 may be provided as pores, for example, wherein the support material 7 has a structure of a foam which in some implementations may be solid or elastic, for instance, or the enclosed cells 8 may be provided as cells of a honeycomb structure formed by the support material 7. In the arrangement as described, the support material 7 forms an elastic supporting structure for the dilatant material 5, allowing the dilatant material 5 in an unloaded state to be in a flowable form. For example, in this arrangement the dilatant material may be provided as a liquid exhibiting thickening as a result of shear strain being rapidly induced to it. The positioning of the support material 7 on the electric conductor 4 may correspond to that described above in relation to the first embodiment of the conductor arrangement 1 and, depending on the properties of the dilatant material 5, it may be partially or entirely arranged within the enclosed cells 8.
[0014] The embodiment of Figure 5 is very similar to the embodiments of Figures 1 - 4 and in the following, this embodiment will be explained mainly by pointing out the differences between these embodiments.
[0015] Figure 5 illustrates schematically a sleeve 9 according to a fifth embodiment of the stiffening conductor arrangement 1. In this embodiment, the layer of dilatant material 5 is provided as at least one sleeve 9, wherein the sleeve has a passage 10 for the cable 2 or busbar 3. In this arrangement, the dilatant material 5 may have a solid form in the unloaded state, for example, or it may be provided within the support material 7 defining the outer shape of the sleeve 9. The dilatant material 5 may also be provided within a flexible outer shell defining the shape of the sleeve 9 and forming a vessel for the dilatant material. The sleeve 9 or several sleeves may be arranged to cover at least a part of the electric conductor 4 by feeding the cable 2 or busbar 3 through the passage 10, and the sleeve 9 may be moved along the length of the conductor to the desired position. If needed, the sleeve 9 may then be secured in place by applying an adhesive between the sleeve 9 and the cable 2 or busbar 3, for example, or it may be secured by dimensioning the passage 10 so that a suitable level of compressive force is created during use between the sleeve 9 and the cable or busbar. In some embodiments, the passage 10 may be arranged to open to the surface of the sleeve 9 across the whole length of the sleeve 9 to facilitate the placement of the sleeve to cover the electric conductor 4. In that case, the sleeve may have a generally U-shaped cross-section.
[0016] The embodiment of Figure 6 is very similar to the embodiments of Figures 1 - 5 and in the following, this embodiment will be explained mainly by pointing out the differences between these embodiments.
[0017] Figure 6 illustrates schematically a sixth embodiment of the stiffening conductor arrangement 1, wherein the arrangement 1 comprises fastening brackets 11 fixed to a surrounding structure 12 of the conductor arrangement 1. Said surrounding structure 12 may be, for example, a fixed beam or a fastening rail as illustrated in the example of Figure 6, or it may be a wall or floor surface limiting the space to which the conductor arrangement 1 is installed. In said example, the fastening bracket 11 also rigidly connects to the busbar 3 with the electric conductor 4 in vicinity of the dilatant material 5. In this context, the term 'in vicinity' means that the fastening bracket 11 and the dilatant material 5 are positioned to influence the same portion of the cable or busbar in an event of forces being subjected to it. In the arrangement as described, the mechanical support structure formed of the fastening brackets 11 and the surrounding structure 12 is arranged to act together with the dilatant material 5 to secure the electric conductor 4 in place. Said arrangement may be used, for example, in locations of the conductor arrangement 1 to which particularly high mechanical forces are subjected during a short circuit condition, and a varying number of fastening brackets 11 and surrounding structures 12 may be used based on the expected load levels.
[0018] The embodiment of Figure 7 is very similar to the embodiments of Figures 1 - 6 and in the following, this embodiment will be explained mainly by pointing out the differences between these embodiments.
[0019] Figure 7 illustrates schematically a cross-cut section according to a seventh embodiment of the stiffening conductor arrangement. In this example, the arrangement 1 also comprises a cooling channel 13 parallel to the electric conductor 4, wherein a flow of a dilatant material fluid 14 is provided to the cooling channel 13. In more detail, the cooling channel 13 in said example is arranged to surround the electric conductor 4, such that the dilatant material fluid 14 flows in a conduit delimited at its inner side by the electric conductor 4. In other embodiments, the cooling channel 13 may also be arranged to run as a separate unit from the electric conductor 4, for example. With the arrangement as described, an active cooling system is provided to the conductor arrangement 1, allowing an electric conductor 4 of a smaller cross-sectional area to be used than would otherwise be possible with a given electric current. By simultaneously providing the dilatant material fluid to act as the cooling medium, the benefits as disclosed above in relation to the layer of the dilatant material 5 may also be further enhanced. That is, the dilatant material fluid 14 provided to the cooling channel 13 may be used to further stiffen the conductor arrangement 1 as a response to the electric conductor 4 being rapidly moved. The dilatant material fluid 14 may comprise the same substance as used in the layer of the dilatant material 5, or it may be selected differently based on, for example, its desired heat capacity or dilatant properties. Though Figure 7 illustrates by way of example that dilatant material is provided both in the cooling channel 13 as a fluid and in the dilatant material 5 layer, in some embodiments the illustrated dilatant material layer 5 may be replaced by a layer of some other material, such as with a layer of an insulating material.
[0020] To prevent overheating of the conductor arrangement 1 during use, also passive means of cooling may be implemented to the arrangement according to the previous examples. Namely, by choosing the dilatant material 5 to have a maximized heat capacity or, for example, a heat capacity greater than that of the electric conductor 4, a lower rate of heating is achieved at the areas of the electric conductor covered by the dilatant material 5. That is, in the arrangement as described the excess thermal energy of the electric conductor 4 is absorbed by the dilatant material 5, the dilatant material simultaneously experiencing only a minor change in temperature by virtue of its higher heat capacity. The dilatant material 5 may also have a specific heat capacity higher than the specific heat capacity of the conductive material used for the electric conductor, for example copper. The arrangement as described may be particularly suitable for moderating sudden temperature fluctuations of the electric conductor 4 resulting from, for example, highly cyclical loads during use or unexpected short circuit conditions.
[0021] To restrict movement of a cable 2 or a busbar 3 according to, for example, any one of the examples of Figures 1 to 7 during a short circuit, the electric conductor 4 of the cable 2 or busbar 3 may be at least partially covered with the layer of the dilatant material 5. For example, said covering may be performed during the manufacture of the cable 2 or busbar 3 by providing the dilatant material 5 through a continuous or discontinuous deposition process, e.g. extrusion, or through a process of arranging predefined units or segments of the dilatant material 5 to cover the electric conductor 4 at predefined locations. Said predefined locations may be based on, for example, estimated or calculated positions of highest shear forces experienced by the electric conductor 4 during use, or the units of dilatant material 5 may be provided at predefined regular intervals. In some embodiments, the dilatant material 5 may also be provided to the electric conductor 4 only after the cable arrangement 1 has been installed to its use location.
[0022] To obtain an electrically insulated conductor arrangement 1, the electric conductor 4 may be covered with the electric insulator material 6 before or after at least partially covering the electric conductor 4 with the layer of the dilatant material 5. In both said cases, the insulator material 6 may be provided through, for example, a continuous deposition process. In case a dilatant material 5 having a flowable form in the unloaded state is to be used between the electric conductor 4 and the insulator material 6, the dilatant material may be, for example, injected or extruded after or simultaneously with the electric insulator material 6.
[0023] In the embodiment according to the example of Figure 4, the covering of the electric conductor 4 with the dilatant material 5 may be done by at least partially covering the electric conductor 4 with the support material 7 and by impregnating the support material 7 with the dilatant material 5. Said impregnation may be done by, for example, submerging the support material 7 into a supply of the dilatant material 5, and it may be performed before or after the covering of the electric conductor 4 with the support material 7. In some embodiments, the dilatant material 5 may also be provided in the form of one or several sleeves 9 as described above, wherein said sleeve or sleeves 9 may be arranged to at least partially surround the electric conductor 4. In said arrangement, the dilatant material 5 may be easily provided to the desired location of the electric conductor 4, for example after the conductor arrangement 1 has been secured to its use location.
1. A stiffening conductor arrangement (1), comprising:
a cable (2) or busbar (3) with an electric conductor (4), characterized in that the conductor arrangement (1) further comprises:
a layer of a dilatant material (5) covering at least a part of the electric conductor (4).
a cable (2) or busbar (3) with an electric conductor (4), characterized in that the conductor arrangement (1) further comprises:
a layer of a dilatant material (5) covering at least a part of the electric conductor (4).
2. The stiffening conductor arrangement (1) according to claim 1, characterized in that the electric conductor (4) is covered with an electric insulator material (6), wherein
the dilatant material (5) is arranged between the electric conductor (4) and the electric
insulator material (6).
3. The stiffening conductor arrangement (1) according to claim 1, characterized in that the electric conductor (4) is covered with an electric insulator material (6), wherein
the electric insulator material (6) is arranged between the electric conductor (4)
and the dilatant material (5).
4. The stiffening conductor arrangement (1) according to any one of the claims 1 to 3,
characterized in that the electric conductor (4) is at least partially covered with a support material
(7) having a structure comprising enclosed cells (8), and
the dilatant material (5) is at least partially arranged within the enclosed cells (8).
the dilatant material (5) is at least partially arranged within the enclosed cells (8).
5. The stiffening conductor arrangement (1) according to any one of the claims 1 to 4,
characterized in that the layer of the dilatant material (5) is provided as at least one sleeve (9) having
a passage (10) for the cable (2) or busbar (3).
6. The stiffening conductor arrangement (1) according to any one of the claims 1 to 5,
characterized in that the arrangement (1) further comprises at least one fastening bracket (11) fixed to
a surrounding structure (12) of the conductor arrangement (1) and rigidly connecting
to the cable (2) or busbar (3) in vicinity of the dilatant material (5).
7. The stiffening conductor arrangement (1) according to any one of the claims 1 to 6,
characterized in that the dilatant material (5) is in a flowable form in an unloaded state of the dilatant
material (5).
8. The stiffening conductor arrangement (1) according to any one of the claims 1 to 7,
characterized in that the dilatant material (5) has a heat capacity that is greater than a heat capacity
of the electric conductor (4).
9. The stiffening conductor arrangement (1) according to any one of the claims 1 to 8,
characterized in that the arrangement (1) comprises a cooling channel (13) parallel to the electric conductor
(4), and a flow of a dilatant material fluid (5, 14) is provided to the cooling channel
(13).
10. The stiffening conductor arrangement (1) according to any one of the claims 1 to 9,
characterized in that the electric conductor (4) of the cable (2) or busbar (3) is an electric conductor
for high current power distribution.
11. A method for restricting movement of a cable (2) or busbar (3) during a short circuit,
characterized in that the method comprises:
covering an electric conductor (4) of the cable (2) or busbar (3) at least partially with a layer of a dilatant material (5).
covering an electric conductor (4) of the cable (2) or busbar (3) at least partially with a layer of a dilatant material (5).
12. The method according to claim 11, characterized in that after the at least partially covering the electric conductor (4) with the layer of
the dilatant material (5), the electric conductor (4) with the dilatant material (5)
is covered with an electric insulator material (6).
13. The method according to claim 11, characterized in that before the electric conductor (4) is at least partially covered with the layer of
the dilatant material (5), the electric conductor (4) is covered with an electric
insulator material (5).
14. The method according to any one of the claims 11 to 13, characterized in that the at least partially covering the electric conductor (4) with the dilatant material
(5) comprises:
at least partially covering the electric conductor (4) with a support material (7), and
impregnating the support material (7) with the dilatant material (5).
15. The method according to any one of the claims 11 to 13, characterized in that the at least partially covering the electric conductor (4) with the dilatant material
(5) comprises:
providing the dilatant material (5) as at least one sleeve (9), and
arranging the sleeve (9) to at least partially surround the electric conductor (4).