Power cable including outer sheath of braided layer of dissimilar metals for protective earth

Abstract

To provide a power cable including an outer sheath of a braided layer of dissimilar metals for protective earth.SOLUTION: A power cable includes at least one core disposed at the center of the power cable, and a metallic outer sheath surrounding the core, where all of the cores are made of conductors for power transmission, the outer sheath is made of a plurality of braided layers of dissimilar metals or one or more braided layers made of dissimilar metal wires, and the outer sheath is grounded and has a cross-sectional area that provides protective earth of the cable. The power cable has a simplified structure, and reduced diameter and weight, and can be easily installed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a power cable having a protective earth, and more particularly to a power cable including an armor of braided layers of dissimilar metals to provide a protective earth. [Background technology]

[0002] "Protective Earth" means the earthing of one or more points on equipment for the purpose of protecting against electric shock in the event of a fault. Protective Earth may be provided from a ground source through a power cable to a distal device.

[0003] The structure of a conventional power cable is shown in Figure 1. As illustrated in Figure 1, the power cable includes three cores (11, 12, 13) in the center. Each of the cores (11, 12, 13) includes a conductor and an insulator surrounding it. Therefore, the cores (11, 12, 13) are electrically isolated from each other. The power cable (10) is a single-phase cable. Therefore, it includes two cores (11, 13) for supplying AC or DC power. The remaining core (12) provides a protective earth.

[0004] Particularly in the case of power cables used on ships or offshore units, large amounts of power must be safely delivered. The risk of equipment failure, electric shock or fire during a voyage is very serious, and the greater the amount of power transmitted by a power cable, the greater the tolerance that must be allowed for due to protective earthing.

[0005] The International Electrotechnical Commission (IEC) standards IEC 60092 and IEC 61892 govern the electrical installations on ships and offshore units, including power cables. Therefore, power cables used on ships or offshore units must comply with the above standards.

[0006] However, for power cables laid in limited spaces such as on ships or offshore units, miniaturization and weight reduction are also very important, and therefore there is a need to provide a power cable that can be made smaller and lighter while still providing a stable protective earth. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a power cable that provides a stable protective earth while simplifying the structure and reducing the cable diameter and weight. [Means for solving the problem]

[0008] To achieve the above-mentioned object, the present invention provides a power cable including at least one core disposed at the center of the power cable and a metal sheath surrounding the core, wherein all of the cores are made of conductors for power transmission, and the sheath is made of multiple braided layers of dissimilar metals, and the sheath has a cross-sectional area that provides a protective earth for the cable when grounded. The braided layer has the advantages of being electrically conductive and flexible.

[0009] Preferably, the sheath may include a first braided layer and a second braided layer, the first braided layer being made of galvanized iron wire, and the second braided layer being made of uncoated or tin-coated soft copper wire, copper alloy wire, or a non-magnetic metal with good electrical conductivity, etc. To prevent corrosion at the contact points of metals with different oxidation degrees, an insulating separator layer may be provided between the first braided layer and the second braided layer.

[0010] On the other hand, the present invention provides a power cable comprising at least one core arranged in the center of the power cable and a metallic sheath surrounding the core, all of the cores being composed of conductors for power transmission, the sheath comprising one or more braided layers made of dissimilar metal wires, and the sheath having a cross-sectional area that provides a protective earth for the cable when grounded.

[0011] Preferably, the braided layer can be formed by braiding a first wire and a second wire, where the first wire is made of galvanized iron wire and the second wire is made of uncoated or tin-coated soft copper wire, copper alloy wire, or a non-magnetic metal with good electrical conductivity. In addition, the first wire and the second wire can be braided in different twist directions. For example, the first wire is arranged in the S direction and the second wire is arranged in the Z direction. The difference in physical properties of wires made of different materials can be offset by their consistent and regular arrangement.

[0012] The power cable of the present invention may be used on ships, in which case the cross-sectional area of ​​the sheath perpendicular to the longitudinal direction of the cable is within the range specified in IEC 60092-352 or IEC 60092-401.

[0013] IEC 60092-352 or IEC 60092-401 standards specify the dimensions of earthing conductors and earthing devices for electrical cables installed on ships. Some of them are listed below.

[0014] [Table 1]

[0015] [Table 2]

[0016] Additionally, the power cable of the present invention may be used in offshore units, where the cross-sectional area of ​​the sheath perpendicular to the longitudinal direction of the cable is within the range specified in IEC 61892-6.

[0017] The IEC 62892-6 standard lists the dimensions of earthing conductors and earthing devices for electrical cables installed in offshore units, some of which are listed below.

[0018] [Table 3]

[0019] According to the table above, the cross-sectional area (Q) of the current-carrying conductor (1 phase or 1 pole) is 16 mm 2 If the cross-sectional area of ​​the current-carrying conductor (Q) is less than 16 mm, the cross-sectional area of ​​the grounding conductor must be at least the cross-sectional area (Q) of one phase or one pole conductor. 2 If it exceeds 16 mm, the cross-sectional area of ​​the earth conductor shall be at least 50% of Q, but not less than 16 mm. 2 It must be more than or equal to this.

[0020] Preferably, according to one embodiment of the present invention, the braided layer of the outer sheath can be produced using a braiding machine having a number of strokes corresponding to the cross-sectional area of ​​the braided layer. As the number of strokes increases, the number of braided wires per unit length of the cable that can be braided increases, resulting in a larger cross-sectional area of ​​the braided layer.

[0021] beneficial effects The power cable according to the present invention is made of braided layers of dissimilar metals and is configured to provide a protective earth by means of an armor having a sufficient cross-sectional area around the core, thereby eliminating the protective earth core of conventional cables and thereby reducing the manufacturing costs of the power cable.

[0022] In particular, in the case of power cables laid in limited spaces such as on ships or offshore units, miniaturization and weight reduction are important technical challenges, and the present invention has the advantage that by eliminating the core wire, it is possible to make a power cable smaller in diameter and lighter with the same functions and performance.

[0023] In addition, in the case of conventional power cables that include a core for protective earthing, the exterior must be separately grounded within the housing in addition to being connected to a protective earth by connecting to a switchboard or distribution board. However, the power cable of the present invention only requires protective earthing via the exterior, which greatly simplifies the cable installation work. [Brief explanation of the drawings]

[0024] [Figure 1] 1 shows a cross-sectional view of a prior art power cable. [Figure 2] 1 shows a cross-sectional view of a power cable according to one example of the present invention. [Figure 3] 1 illustrates a braided layer configuration according to one example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will now be described in detail by way of preferred examples with reference to the accompanying drawings.

[0026] FIG. 2 shows a cross-sectional view of a power cable according to one example of the present invention.

[0027] As shown, power cable 100 includes a core portion 110 including cores 111, 112, a filler material 120, an insulating layer 130, an outer jacket 140, and a sheath 150. However, this configuration of power cable 100 is exemplary only, and additional known components may be added or some components may be omitted.

[0028] The core portion 110 is located at the center of the power cable 100 in cross section. The core portion 110 includes multiple cores 111, 112. That is, the power cable 100 is a multi-core cable. While this embodiment includes two cores 111, 112, the number of cores is not limited. For example, if the present invention is applied to a commonly used three-phase cable, the core portion 110 includes four cores corresponding to the three phases and the neutral conductor.

[0029] The power cable (100) having a core portion (110) including two cores (111, 112) can form a DC circuit or a single-phase AC circuit connecting the positive and negative poles.

[0030] The filler material 120 fills the spaces between the core sections 110, giving the cable 100 a circular cross-section, making it more durable and easier to handle. The insulating layer 130 electrically isolates the interior of the power cable 100 from the outside. The outer jacket 140, also known as a metal screen, protects the insulating layer 130 and shields it from external electromagnetic influences. The sheath 150 is typically made of impact-resistant and chemical-resistant plastic or rubber, which protects the interior from environmental influences.

[0031] In particular, the sheath (140) of the power cable (100) of the present invention is formed using one or more braided layers of dissimilar metals to have a cross-sectional area sufficient to provide a protective earth, and is grounded to a distribution board through a ground terminal, thereby providing a protective earth for the cable.

[0032] The power cable (100) according to the present invention may be used for marine vessels, in which case the cross-sectional area of ​​the sheath (140) complies with the provisions of IEC 60092-352 or IEC 60092-401.

[0033] Additionally, the power cable (100) according to the present invention may be used for offshore units, in which case the cross-sectional area of ​​the sheath (140) complies with the provisions of IEC 61892-6.

[0034] As mentioned in the table above, the conductor cross-sectional area of ​​the cores (111, 112) is 16 mm 2 Below (Q≦16mm 2 ), the cross-sectional area of ​​the sheath (140) is equal to or greater than the cross-sectional area (Q). 2 Larger (Q>16mm 2 ) In this case, the cross-sectional area of ​​the outer casing (140) is 50% (Q / 2) or more of the cross-sectional area, and is 16 mm 2 Greater than.

[0035] Increasing the cross-sectional area of ​​the sheath 140 by wrapping the metal tape multiple times can cause the power cable 100 to lose flexibility. Therefore, in the present invention, the sheath 140 is made of a braided material or a braided layer is added to the sheath 140.

[0036] According to one embodiment, the sheath (140) may include multiple braided layers surrounding the core portion (110). The multiple braided layers can achieve the desired cross-sectional area of ​​the protective earth conductor. The multiple braided layers are made of different metals. Specifically, the sheath (140) includes a first braided layer and a second braided layer, where the first braided layer is made of galvanized iron wire and the second braided layer is made of uncoated or tin-coated soft copper wire, copper alloy wire, or a non-magnetic metal with good electrical conductivity. Manufacturing costs can be reduced by combining iron, which is cheaper than copper. However, when different metal materials come into contact, one or the other, the iron may corrode (oxidize) due to the difference in oxidation (ionization) degree between copper and iron. Therefore, a separator layer can be interposed between the braided layers to prevent corrosion. The separator layer can be formed by winding a polyester separator tape.

[0037] According to other embodiments, the sheath (140) may include at least one braided layer made of wires of different metals. As shown in FIG. 3, the braided layer (300) may be formed by cross-braiding wires (310, 320) of different metals. Here, the first wire (310) may be made of galvanized iron wire, and the second wire (320) may be made of uncoated or tin-coated soft copper wire, copper alloy wire, or a non-magnetic metal with good electrical conductivity. In the illustrated embodiment, for example, the first wire (310) may be twisted in the S direction (left edge), and the second wire (320) may be twisted in the Z direction (left edge).

[0038] Additionally, the braided layer of the power cable according to the invention can be produced on a braiding machine, the cross-sectional area of ​​the braided layer can be increased by increasing the number of strokes of the braiding machine, i.e. the number of spindles around which the wire is wound.

[0039] In the power cable according to the present invention configured as described above, the protective earth is provided by the thick outer sheath, so that the conventional core for the protective earth can be omitted, thereby reducing the diameter and weight of the power cable and reducing manufacturing costs. In addition, this power cable can be connected to a switchboard or distribution board by simply grounding the outer sheath, which makes cable installation easier.

[0040] Although the present invention has been described with reference to specific examples and drawings, it is not limited by these examples, and those skilled in the art may make various modifications or improvements from the description. The gist of the present invention should be understood only from the following claims, and all equivalent or similar modifications of the claims are intended to be included within the scope of the present invention. [Explanation of symbols]

[0041] 100 Power Cable 110 Core part 111 First Core 112 Second Core 120 Filling material 130 Insulating layer 140 Exterior 150 sheath 300 braided layers 310 First Wire 320 Second Wire

Claims

1. A power cable, At least one core disposed at the center of the power cable; a metal exterior surrounding the core; Including, All of the cores are made of a conductor for power transmission; 1. A power cable, wherein the sheath is made of multiple braided layers of dissimilar metals, and wherein the sheath has a cross-sectional area that is grounded and provides a protective earth for the cable.

2. The sheath includes a first braided layer and a second braided layer, the first braided layer being made of galvanized iron wire, and the second braided layer being made of uncoated or tin-coated soft copper wire, copper alloy wire, or a non-magnetic metal with good electrical conductivity; 10. The power cable of claim 1, wherein an insulating separator layer is provided between the first braided layer and the second braided layer.

3. A power cable, At least one core disposed at the center of the power cable; a metal exterior surrounding the core; Including, All of the cores are made of a conductor for power transmission; 1. A power cable, wherein the sheath includes one or more braided layers made of dissimilar metal wires, and the sheath has a cross-sectional area that is grounded and provides a protective earth for the cable.

4. The braided layer is formed by braiding a first wire and a second wire, the first wire being made of a galvanized iron wire, and the second wire being made of an uncoated or tin-coated soft copper wire, a copper alloy wire, or a non-magnetic metal with good electrical conductivity; 4. The power cable of claim 3, wherein the first wire and the second wire are braided with different twist directions.

5. A power cable according to any one of claims 1 to 4, for use in installation within a ship or offshore unit.

6. 6. The power cable of claim 5, wherein the sheath has a cross-sectional area perpendicular to a longitudinal direction of the cable within the range of cross-sectional areas specified in IEC 60092-352, IEC 60092-401 or IEC 61892-6.

7. The cross-sectional area (Q) of the conductor is 16 mm ２ 5. The power cable according to claim 1, wherein the cross-sectional area of ​​the sheath is at least equal to the cross-sectional area (Q) of the conductor.

8. 5. The power cable according to claim 1, wherein the braided layer of the sheath is manufactured by a braiding machine having a number of strokes corresponding to the cross-sectional area.

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