KR20220138777A - Power Cable System Having Different Conductors Connecting Part And Connetcting Method of Power Cables Having Different Conductors - Google Patents

Abstract

The present invention relates to a power cable system having different conductive bonding units and a power cable connecting method having different conductors which do not apply a separate sleeve member and the like when a power cable with different conductors is connected so as to reduce costs, a weight and a volume and obtain sufficient bending strength or durability in different conductive bonding units even when a tensile force and bending are applied together.

Description

Power Cable System Having Different Conductors Connecting Part And Connecting Method of Power Cables Having Different Conductors

The present invention relates to a power cable system having a dissimilar conductor junction and a method for connecting a power cable having dissimilar conductors. More specifically, the present invention secures sufficient flexural strength at the dissimilar conductor junction even when tensile force and bending are applied together when connecting a power cable having a dissimilar conductor, thereby preventing damage to the junction and securing durability A power cable system having a dissimilar conductor junction and a power cable connection method having a dissimilar conductor are provided.

The power cable for power supply may include a copper or aluminum-based conductor, an insulating layer, a semi-conductive layer, an outer jacket, and the like.

A cable for power transmission consists of a conductor and an insulator, and the conductor requires high electrical conductivity to minimize electrical energy loss. Copper and aluminum have excellent electrical conductivity and are cost-competitive materials for conductors. Copper is superior in electrical and mechanical properties except for density. Aluminum conductors have been limitedly applied to overhead power lines, etc.

However, as the price of copper raw materials rises, the price of copper is 4 to 6 times higher than that of aluminum of the same weight, so the demand for applying an aluminum conductor to a power transmission cable is increasing. Since copper has been mainly applied to conductors for existing cables, it is expected that the demand for direct bonding between copper conductors and aluminum conductors will increase with the spread of aluminum applications.

Copper as a conductor material has good conductivity compared to aluminum, but is expensive, and aluminum has lower conductivity than copper but is inexpensive.

In addition, a conductor composed of a plurality of wires is mainly used as a conductor of a power cable in consideration of flexibility, etc., and different conductors of different materials are used, such as when a power cable having a copper conductor and a power cable having an aluminum conductor are connected. In the case of intermediate connection of power cables equipped with In the process, a copper conductor composed of a plurality of wires has voids between the wires, and an oxide film is formed along each void in a high-temperature welding environment, which may cause a problem in that the quality of the welded portion is deteriorated.

Accordingly, in Korean Patent No. 10-1128106, etc., a method of connecting conductors using a dedicated sleeve member for bonding dissimilar conductors such as copper or aluminum is used. The sleeve member may include a first metal part having an insertion hole for inserting a first conductor made of copper or the like, and a second metal part having a bonding surface to which the aluminum-based second conductor is Mig or Tig welded.

A first conductor made of copper or the like is inserted into the insertion hole of one side of the sleeve member and pressed, and the aluminum conductor may be joined to the other side joining surface by welding or the like.

The sleeve member in the form of a joined metal is expensive, and since two additional processes of pressing and welding are required through the sleeve member, problems of increased cost and additional process may occur.

In addition, in order to solve this problem, Korean Patent Application Laid-Open No. 10-2020-0069967 has introduced a structure and a joining method for joining dissimilar conductors by resistance welding without using a sleeve member, but the As one of the performance tests, it was confirmed that cracks occurred in the conductor joint of the junction box when performing a tensile bending test in which a tensile force was applied while a pair of dissimilar conductor submarine cables connected to the junction box were bent with a certain radius of curvature.

23 is a power cable having a copper conductor, a power cable having an aluminum conductor, and a power cable system including an intermediate connection structure comprising a conductor junction by the method disclosed in Korean Patent Application Laid-Open No. 10-2020-0069967 after performing a tensile bending test. An enlarged view of the dissimilar conductor junction 11' is shown.

In the case of a dissimilar conductor joint in which the first conductor 10A, which is a copper conductor, and the second conductor 10B, which is an aluminum conductor, respectively, are connected by the method disclosed in Korean Patent Laid-Open Publication No. 10-2020-0069967 without the sleeve member, only the horizontal tensile force When applied, it was confirmed to have sufficient tensile strength, but when bending and tensile force were applied together in a tensile bending test according to the test standards of the cable consumer, deformation, breakage, and cracking in the first and second conductor regions, which are the respective conductor regions. Although no back breakage occurred, it is shown that cracks (C) occurred at the dissimilar conductor junction.

That is, the flexural strength at the dissimilar conductor junction 11' is lower than the flexural strength of the first conductor in the copper conductor region and the flexural strength of the second conductor in the aluminum conductor region. C) can be understood to have occurred.

In addition, FIG. 24 shows a method for bonding dissimilar conductors, as described in Korean Patent Application Laid-Open No. 10-2020-0069969, which is made of the same material as copper, which is the first conductor 10A among dissimilar conductors, and includes a first metal insert It is made of the same material as aluminum as the second conductor 10B and includes a second metal part including a protrusion, and has a structure in which the protrusion of the second metal part is inserted into the insertion part of the first metal part and joined by friction welding. A power cable including an intermediate connection structure in which the first conductor 10A and the second conductor 10B are joined by using a connecting conductor with the first conductor 10A in which a break (br) occurred in the course of performing a tensile bending test and The second conductor 10B is shown.

Similarly, the joint structure disclosed in Korean Patent Application Laid-Open No. 10-2020-0069969 was also confirmed to have sufficient tensile strength when only horizontal tensile force was provided, but when bending and tensile force were provided together, the joint of the conductor was broken and fractured (br) . The insertion part and the protrusion with the locking groove formed around the conductor joint were joined to withstand horizontal tensile force due to the locking structure, but sufficient bending strength could not be secured in an environment where bending and bending were provided.

Therefore, in order to secure sufficient durability even in the harsh submarine environment of the intermediate connection structure of the power cable having different conductors, a method for improving the flexural strength at the junction of the conductors constituting the intermediate connection structure of the dissimilar conductor power cable is required. reached.

The present invention secures sufficient flexural strength at the junction of dissimilar conductors even when tensile force and bending are applied when connecting a power cable having dissimilar conductors, thereby preventing damage to dissimilar conductor junctions and securing durability. An object to be solved is to provide a power cable system having a junction and a power cable connection method having a dissimilar conductor.

In order to solve the above problems, the present invention provides a first power cable including a first conductor, a second power cable including a second conductor, and a cable connection structure for connecting the first power cable and the second power cable. A power cable system including and a melting point of the first conductor is greater than a melting point of the second conductor, and the cable connection structure includes a dissimilar conductor junction part joining the first conductor and the second conductor together, and the dissimilar conductor junction part includes a first Pre-processing of the first conductor including a conductor volume ratio increasing region and a second conductor volume ratio increasing region, wherein the first conductor volume ratio increasing region increases the volume ratio by a predetermined length from the joint surface cs1 of the first conductor The second conductor volume ratio increasing region is formed by performing preliminary processing of the second conductor to lower the volume ratio by a predetermined length from the joint surface cs2 of the second conductor, and then the first conductor and the second conductor It is possible to provide a power cable system, characterized in that formed by resistance welding.

In addition, in the preliminary processing of the first conductor, after joining a pair of first conductors by welding, the joint portion may be cut and the cut surface may be configured as the joint surface cs1 of the first conductor.

In addition, the volume ratio of the first conductor may be 98% or more by a predetermined length from the bonding surface cs1 of the first conductor due to the preliminary processing of the first conductor.

Here, the first conductor may be made of copper or a copper alloy material, and the second conductor may be made of aluminum or an aluminum alloy material.

In this case, the preliminary processing of the second conductor may form a melt penetration path in the longitudinal direction of the second conductor from the bonding surface cs2 of the second conductor before bonding the first conductor and the conductor.

In addition, the volume ratio of the second conductor may be less than or equal to 90% by a predetermined length from the bonding surface cs2 of the second conductor by the preliminary processing of the second conductor.

In addition, the melt penetration path may be formed by drilling a plurality of points on the joint surface cs2 of the second conductor using a drill.

In addition, the melt penetration path may be formed by cutting and removing a portion of the plurality of strands constituting the second conductor from the bonding surface cs2 of the second conductor using a cutting tool.

Here, the volume ratio of the volume ratio increasing region of the second conductor may be 98% or more from the bonding surface cs to at least 3 mm in the longitudinal direction of the second conductor.

In this case, a heterogeneous conductor junction, characterized in that the diameter of the first conductor is smaller than the diameter of the second conductor may be provided.

In addition, in the dissimilar conductor junction part, an O-ring having an inclined outer circumferential surface may be joined together in order to close the step difference due to the difference in diameter between the first conductor and the second conductor with an inclined surface.

In addition, the dissimilar conductor junction portion may be configured by joining the first conductor and the second conductor by resistance welding.

Here, the first conductor or the second conductor may be a circular compression conductor.

In this case, the first conductor or the second conductor may be a flat conductor.

In addition, in order to solve the above problems, the present invention provides a first power cable including a first conductor, a second power cable including a second conductor, and a cable connection for connecting the first power cable and the second power cable A power cable system including a structure, wherein the first power cable includes a first conductor made of a plurality of wires, and the second power cable includes a plurality of wires and a second conductor made of a material different from that of the first conductor. wherein the melting point of the first conductor is greater than the melting point of the second conductor, and the cable connection structure includes a dissimilar conductor junction part joining the first conductor and the second conductor together, and the dissimilar conductor junction part It comprises a region for increasing the volume fraction of the first conductor and an region for increasing the volume fraction for the second conductor with respect to the junction surface (cs), wherein the flexural strength of the junction of the dissimilar conductors is greater than the flexural strength of the second conductor A power cable system can be provided.

In addition, the volume ratio of the volume ratio increasing region of the second conductor may be 98% or more from the bonding surface cs to at least 3 mm in the longitudinal direction of the second conductor.

In addition, the first conductor may be made of copper or a copper alloy material, and the second conductor may be made of aluminum or an aluminum alloy material.

Here, it may be provided with a heterogeneous conductor junction, characterized in that the diameter of the first conductor is smaller than the diameter of the second conductor.

In this case, the dissimilar conductor junction part is provided with a dissimilar conductor junction, characterized in that an O-ring with an inclined outer circumferential surface is joined together in order to close the step due to the difference in diameter between the first conductor and the second conductor with an inclined surface. can

In addition, the dissimilar conductor junction portion may be configured by joining the first conductor and the second conductor by resistance welding.

In addition, the volume ratio increasing region of the first conductor may be processed to have a high volume ratio by a predetermined length in advance before welding between the first conductor and the second conductor.

In addition, the first conductor may be processed so that the volume ratio is 98% or more by a predetermined length from the bonding surface cs1 of the first conductor before bonding to the second conductor.

Here, in the method of processing the first conductor with a volume ratio higher than a predetermined size by a predetermined length from the bonding surface cs1 of the first conductor, after bonding a pair of first conductors by welding, the bonding portion is cut and the cut surface may be configured as the bonding surface cs1 of the first conductor.

In this case, before joining the first conductor and the second conductor, a melt permeation path is formed in the longitudinal direction of the second conductor from the bonding surface cs2 of the second conductor, so that the volume ratio of the second conductor is equal to or less than a predetermined size. can be processed

In addition, the second conductor may be processed to have a volume ratio of 90% or less.

In addition, the melt penetration path may be formed by drilling a plurality of points on the joint surface cs2 of the second conductor using a drill.

In addition, the melt penetration path may be formed by cutting and removing a portion of the plurality of strands constituting the second conductor from the bonding surface cs2 of the second conductor using a cutting tool.

Here, the first conductor or the second conductor may be a circular compression conductor.

In this case, the first conductor or the second conductor may be a flat conductor.

In addition, in order to solve the above problems, the present invention provides a first power cable including a first conductor made of a plurality of circular wires and a second conductor comprising a plurality of circular wires made of a material different from the first conductor. 2 . A method of connecting a power cable for connecting a power cable, comprising: a preliminary processing step of a first conductor for processing a volume ratio higher than a predetermined size by a predetermined length from a joint surface (cs1) of the first conductor; a pre-processing step of processing a second conductor with a volume ratio lower than a predetermined size by a predetermined length from the joint surface (cs2) of the second conductor; and a resistance welding step of forming a dissimilar conductor junction by joining the bonding surface (cs1) of the first conductor and the bonding surface (cs2) of the second conductor by resistance welding. can provide

In addition, the resistance welding step may be performed by passing a current through the first conductor and the second conductor to melt and pressurize the first conductor and the second conductor.

In the resistance welding step, in a welding jig for welding the first conductor and the second conductor, the exposed length of the first conductor may be smaller than the exposed length of the second conductor.

Here, in the preliminary processing step of the first conductor, a junction is formed by joining a pair of first conductors by welding such that the volume ratio is 98% or more from the first conductor junction surface cs1 by a predetermined length, and the junction part It may be carried out in a method of cutting the cut surface to become the bonding surface cs1 of the first conductor.

In this case, in the preliminary processing step of the second conductor, the bonding surface of the second conductor ( cs2) may be performed by a method of forming a melt penetration path by a predetermined length in the longitudinal direction of the second conductor.

In addition, after the resistance welding step, the volume ratio of the volume ratio increasing region of the second conductor constituting the dissimilar conductor junction may be 98% or more from the junction surface cs to at least 3 mm in the longitudinal direction of the second conductor.

In addition, during the resistance welding, the welding temperature may be lower than the melting point of the first conductor and 5% to 15% higher than the melting point of the second conductor.

According to the power cable system having a dissimilar conductor junction and the power cable connection method having dissimilar conductors according to the present invention, even when tensile force and bending are applied together, the volume ratio of the conductor in the dissimilar conductor junction is increased to ensure sufficient flexural strength Therefore, it is possible to prevent damage to the dissimilar conductor junction, improve durability, and improve the reliability of the intermediate connection structure.

In addition, according to the power cable system having a dissimilar conductor junction and the power cable connection method having dissimilar conductors according to the present invention, it is possible to improve the workability of dissimilar conductor bonding by applying fusion resistance welding.

1 shows a state in which a copper circular compression conductor as a pair of first conductors is respectively mounted on a welding jig.
2 illustrates a process of joining a pair of first conductors by resistance welding.
3 shows a process of cutting the joint along a cutting line after removing the burr from the joint of the joined first conductor.
4 shows an image of a state in which a pair of first conductors made of copper are bonded to each other.
FIG. 5 shows an image of a state in which burrs are removed from the junction of the first conductor of FIG. 4 .
Fig. 6(a) shows an image of a new bonding surface of the first conductor formed by cutting the bonding portion of the pair of first conductors, and Fig. 6(b) is before bonding the pair of first conductors by resistance welding. The original first conductor bonding surface is shown.
7 to 9 show a conceptual diagram of a process of forming a melt penetration path on the bonding surface of the second conductor in the form of an aluminum-based circular compressed conductor or a flat conductor of the present invention.
Fig. 10 shows a state in which a pair of a copper circular compressed conductor as a first conductor and an aluminum circular compressed conductor as a second conductor are respectively mounted on a welding jig.
11 is a diagram illustrating a process of joining joint surfaces of the first conductor and the second conductor by resistance welding.
12 illustrates a state in which a burr is removed from a joint portion of the joined first conductor and the second conductor, and the joining is completed.
13 shows a stripped perspective view of a conductor and an XLPE insulation layer applied with a copper or aluminum-based element of the present invention compressed into a circular shape.
14 shows a stripped perspective view of a power cable to which a copper or aluminum-based flat conductor and an XLPE insulation layer of the present invention are applied.
15 is a cross-sectional view of an intermediate connection structure of a power cable according to an embodiment of the present invention.
16 is a cross-sectional view showing an intermediate connection structure of a power cable according to an embodiment of the present invention.
17 is a perspective view of a dissimilar conductor junction applicable to the intermediate connection structure of the power cable shown in FIG. 16 .
18 to 20 show a conductor bonding process of the dissimilar conductor junction shown in FIG. 17 .
21 shows a three-point bending test, which is a test method that can confirm flexural strength.
22 shows an image of a three-point bending test result of a dissimilar conductor junction joined by a dissimilar conductor bonding method according to the present invention.
23 shows an example in which a crack is generated at a junction of dissimilar conductors joined by a technique related to Korean Patent Laid-Open No. 10-2020-0069967.
24 shows an example in which a crack is generated at a junction of dissimilar conductors joined by a technique related to Korean Patent Application Laid-Open No. 10-2020-0069969.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed subject matter may be thorough and complete, and the spirit of the present invention may be sufficiently conveyed to those skilled in the art. Like reference numerals refer to like elements throughout.

The suitability of the conductor may be changed in consideration of cost, etc. depending on the environment (land or sea floor, etc.) in which the power cable is installed. Intermediate connection may be performed even when the types of conductors constituting the power cable are different according to the conductor characteristics of the power cable required for each section.

If the type of conductor of the power cable to be connected in the middle is different, the melting point may be different and the degree of oxide film may be different, so it is difficult to guarantee the bonding quality in the junction with a conventional bonding method.

In addition, the conductor may be used in various structures, such as a circular compressed conductor obtained by twisting and compressing a plurality of circular wires or a flat conductor including a plurality of flat wire layers obtained by twisting a plurality of flat wires. First, in relation to a method of connecting a pair of conductors, a method of joining heterogeneous circular compressed conductors will be described.

In the present invention, in constructing an intermediate connection structure for connecting a first power cable and a second power cable, a first conductor composed of a plurality of circular wires of the first power cable or a plurality of circular wires of the second power cable is provided. Alternatively, when a dissimilar conductor junction is formed by bonding a second conductor composed of a flat element wire, a volume ratio increasing region of the first conductor and a volume ratio increasing region of the second conductor are formed in the dissimilar conductor junction with respect to the bonding surface in the dissimilar conductor junction to provide sufficient bending By securing the strength, it is possible to solve the problems of damage such as deformation, breakage, and cracks in the dissimilar conductor junction. It will be described in detail below.

In the following description, the conductor of each power cable is described by taking as an example a circular compressed conductor obtained by twisting and compressing a plurality of circular strands. However, even in the case of a flat conductor composed of flat strands, the same conductor bonding method can be applied only with a different shape of the conductor. have.

As an indicator for judging the empty space inside a conductor of a certain volume, the conductor volume ratio refers to the volume occupied by the conductor excluding the empty space between the wires compared to the total volume defined by the outer circumference of the conductor (= conductor cross-sectional area x conductor length) It is defined as Equation 1 below, and it means that as the volume ratio of the conductor increases, the empty space decreases.

[Equation 1]

The volume ratio of the conductor is a concept similar to the area ratio based on the cross-section of the conductor, but can be distinguished in that it is a concept of volume in which the longitudinal variable of the conductor is reflected.

1 to 6 are conceptual views of the process of processing the volume ratio of the conductor to a higher than a predetermined size by a predetermined length from the bonding surface cs1 of the circular compression conductor made of copper as the first conductor 10A and the processing process show the image.

When resistance welding a conductor made of copper (or copper alloy) and a conductor made of aluminum (or aluminum alloy), the welding is performed at a temperature between the melting point of the copper conductor and the melting point of the aluminum conductor because the melting point of the aluminum conductor is low. In the process, voids exist on the bonding surface of the copper conductor and a thick oxide film is formed along each void, so the quality of the junction may be deteriorated.

Therefore, the present invention is to process the volume ratio of the conductor to a predetermined size or higher by a predetermined length from the joint surface (cs1) of the copper conductor having a high melting point before resistance welding the copper conductor and the aluminum conductor each composed of a circular compression conductor. The process may be performed.

That is, the bonding surface of the copper conductor composed of a circular compression conductor is provided in a form in which voids are removed or minimized, thereby suppressing the generation of an oxide film, etc. can be improved

Meanwhile, the meaning that the volume ratio of the conductor is 100% may be interpreted as meaning that there is no gap inside the conductor.

Therefore, processing the volume ratio higher than a predetermined size by a certain length from the bonding surface cs1 of the copper conductor of the present invention means a process of reducing the void space ratio of the copper conductor to a predetermined size or less.

A process of processing the volume ratio of the conductor to be higher than a predetermined size by a predetermined length from the bonding surface cs1 of the first conductor as a copper conductor joined to a second conductor as an aluminum conductor, which will be described later, will be described in detail.

FIG. 1 shows a state in which a copper circular compression conductor as a pair of first conductors 10A is mounted on a welding jig j, respectively, and FIG. 2 shows a state in which a pair of first conductors 10A are joined by resistance welding. 3 shows the process of removing the burr from the joint of the joined first conductor 10A and cutting the joint along the cutting line.

As shown in FIGS. 1 to 3 , the process of processing the area ratio of the joint surface of the first conductor 10A having a relatively high melting point to be higher than a predetermined size is the bonding of the first conductor 10A of the same material. After welding the surface (cs1') by resistance welding, the burr (b) of the joint portion 11' is removed, and the joint portion 11' is cut along the cutting line (cl) to obtain a new joint surface (cs1). A method for making this possible may be used. The welding of the joint surfaces cs1 ′ of the pair of first conductors 10A may be performed by fusion resistance welding, but is not limited thereto.

4 shows an image of a state in which a pair of first conductors 10A are joined, and FIG. 5 shows an image of a state in which the burr b is removed from the joint 11' of the first conductor 10A. 6(a) shows a new bonding surface cs1 of the first conductor 10A formed by cutting the bonding portion 11' of the pair of first conductors 10A, and FIG. 6(b) is An image of the bonding surface cs1' of the original first conductor 10A before bonding is shown.

4 and 5, the pair of first conductors 10A are welded and recrystallized while forming a burr b in the compression process by a method such as melt resistance welding, and the recrystallized joint 11'. 6(a), the new joint surface cs1, which is the cut surface of the joint portion 11' of the first conductor 10A, is a smooth metal in which few voids existing in the circular compressed conductor are found. It is processed into cotton, and may be processed to increase the volume ratio of the conductor by a predetermined length from the bonding surface cs1.

That is, through the preliminary process shown in Figs. 1 to 5, the first conductor shown in Fig. 6(b) has a plurality of voids between the wires 1, so that the space factor of the original bonding surface cs1' And in a state where the volume ratio of the conductor is relatively low, the first conductor after processing shown in FIG. 6( a ) may have a state in which the volume ratio of the conductor is very high by the area ratio and a certain length of the bonding surface cs1 .

In this way, the area ratio of the joint surface cs1 of the first conductor 10A having a high melting point among the first conductor 10A and the second conductor 10B to be joined and the volume ratio by a predetermined length are set higher than a predetermined size. The processing process can be seen as a process of making the conductor in the junction region into a conductor.

In addition, the process of processing the volume ratio of the conductor to be higher than a predetermined size by a certain length from the bonding surface cs1 of the first conductor 10A is as shown in FIGS. 1 to 6, 1 In addition to the method of joining the conductor 10A and cutting the joint 11', the first conductor 10A joint surface cs1' is heated with a heating jig or the like having a higher melting point than the first conductor 10A. A method of recrystallizing the bonding surface cs1' of the conductor 10A may be used.

In addition, the volume ratio of the conductor from the new bonding surface cs1 of the first conductor 10A by a certain length is preferably about 98% or more, which is higher than the volume ratio of a general circular compressed conductor.

On the other hand, in order to further increase the volume ratio of the conductor by a predetermined length from the new bonding surface cs1 of the first conductor 10A formed by cutting the bonding portion 11' in FIGS. 3 to 6, it is shown in Figs. Before bonding the pair of first conductors 10A, at least one bonding surface cs1' of the pair of first conductors 10A and at least one melt penetration path into it (FIGS. 7 to 12) of reference numeral 4) may be formed. The melt penetration path serves to increase the volume ratio by introducing the melt of the first conductor 10A during the bonding process between the pair of first conductors 10A as will be described later in the second conductor 10B. For example, the melt penetration path is a region in which a hole or a circular element formed by using a drill or the like on the joint surface cs1' of the first conductor 10A is reduced or removed by cutting, respectively (see FIGS. 7 to 9 ). ) can be

Specifically, a plurality of holes may be formed so that the volume ratio is 90% or less by a certain length in the longitudinal direction from the bonding surface cs1' of the first conductor 10A, or it may be formed by cutting a plurality of strands, , in this case, it is preferable that the melt penetration path is dispersedly formed on the bonding surface cs1' of the first conductor 10A.

7 to 9 are conceptual views of a process of forming a melt penetration path on the bonding surface of a second conductor in the form of a circular compressed conductor or a flat conductor of an aluminum-based type.

As described in the background art, the method disclosed in Korean Patent Application Laid-Open No. 10-2020-0069967 and the like can omit a separate sleeve member when bonding the copper-based first conductor 10A and the aluminum-based second conductor 10B. Although it has an advantage in that it can be used, it was confirmed that cracks occurred in the joint through a tensile bending test, etc.

Such a defect is because, when both tensile force and bending are applied, flexural strength is insufficient in the junction region of the first conductor 10A and the second conductor 10B.

Here, 'flexural strength' may be defined as the maximum stress applied to the sample before deformation, fracture, cracking, etc., occurs in the sample in the bending test.

According to the present invention, when the first conductor 10A and the second conductor 10B, which are dissimilar conductors, are joined through resistance welding, etc., the molten material penetrates into the conductor to form a conductor volume ratio increasing region, thereby forming a junction of dissimilar conductors. It was confirmed that the flexural strength could be improved.

That is, in the present invention, the heterogeneous conductor junction part, which is joined to the first conductor and the second conductor, is formed to include the volume ratio increasing region of the first conductor and the volume ratio increasing region of the second conductor with respect to the junction surface cs. It is possible to improve the flexural strength of the conductor joint.

To this end, as described above, in the first conductor having a relatively high melting point, a volume ratio increasing region of the first conductor is formed through preliminary processing to increase the volume ratio by a predetermined length, and through this, bonding with the second conductor The bonding strength can be increased by maximizing the bonding area.

On the other hand, in the case of the second conductor having a relatively low melting point, since it is mainly melted during the fusion resistance welding process, which is the joining process with the first conductor, the volume ratio of the conductor is increased by a certain length from the joint surface through preliminary processing. has no meaning

Accordingly, in the present invention, in order to form a volume ratio increasing region of the second conductor, a melt penetration path is formed by a predetermined length from the joint surface of the second conductor by a method described later to lower the volume ratio, and then the resistance welding process with the first conductor A method of increasing flexural strength by increasing the volume fraction of the second conductor region of the junction in the state where the welding is completed, as a result, by allowing the second conductor having a relatively low melting point to be melted and the resulting melt flows through the melt penetration path was applied.

Specifically, FIG. 7 is a conceptual diagram for explaining the concept of forming a melt penetration path in the second conductor 10B made of aluminum according to the present invention.

As shown in FIG. 7A , the second conductor 10B may be a circular compressed conductor obtained by compressing a plurality of circular element wires 1 in a circular fashion, and even if a plurality of circular element wires are compressed and collected, the second conductor 10B may be formed between the wires. voids cannot be completely eliminated.

As described above, even when the volume ratio is insufficient for a predetermined length from the joint surface of the dissimilar conductor junction to the second conductor 10B having a relatively low melting point, the tensile strength against the horizontal tensile force can be secured, but together with the tensile force When bending is applied, breakage problems such as deformation, breakage, or cracking may occur, so the flexural strength at the junction of the dissimilar conductors is ultimately determined from the junction of the dissimilar conductors by a certain length in the direction of the second conductor with a low melting point. An area for increasing the volume ratio of the second conductor was formed on the assumption that it was proportional to the volume ratio. As a preliminary work for this, the second conductor to be joined was joined before the fusion resistance welding process of the first conductor 10A and the second conductor 10B. A preliminary process was performed to lower the volume ratio of the predetermined length section in the face.

That is, in the present invention, as shown in FIG. 7(b), the second conductor 10B having a low melting point at the junction surface cs of the dissimilar conductor junction where the first conductor 10A and the second conductor 10B are joined. ) direction as a preliminary processing to increase the volume ratio by a certain length, the bonding surface cs2 of the second conductor 10B before bonding of the second conductor 10B and at least one melt penetration path 4 into it formed.

The melt penetration path 4 shown in FIG. 7(b) is narrowed by cutting a hole formed using a drill or the like on the joint surface cs2 of the second conductor 10B or a circular element by a predetermined length, respectively. Alternatively, it may be a removed region, and a plurality of holes are formed so that the volume ratio is 90% or less by a predetermined length in the longitudinal direction from the bonding surface cs2 of the second conductor 10B, or formed by cutting a plurality of strands can do.

In addition, the melt penetration path 4 allows the melt of the second conductor 10B to flow in during the bonding process between the first conductor 10A and the second conductor 10B, thereby increasing the volume ratio and thus improving the flexural strength. In order to do this, it is preferable to disperse and form on the bonding surface cs2 of the second conductor 10B.

The second conductor 10B shown in FIG. 8 shows a cross section of a circular compressed conductor obtained by compressing a plurality of circular element wires made of aluminum, and the second conductor 10B shown in FIG. 9 is a plurality of flat conductors made of aluminum. A cross-section of a conductor composed of

The method of forming the melt penetration path 4 in the second conductor 10B shown in FIGS. 8 and 9 may be a method of forming a plurality of holes to a certain depth using a drill, but cutting processing other than drilling Alternatively, cutting processing may be used.

By forming the melt permeation path 4 on the joint surface CS2 of the second conductor 10B, the second conductor 10B to the depth at which the melt permeation path 4 is formed is 90% or less by volume. The number of holes to be formed, etc. can be determined.

In addition, the melt penetration path 4 is preferably distributed in a concentric circle with respect to the center of the conductor in order to secure flexural strength independent of the bending direction.

Therefore, the second conductor 10B, in which the melt penetration path 4 is formed through drilling, cutting, or cutting, is processed so that the volume ratio of the conductor is about 98% or more from the joint surface cs1 by a certain length. In the case of joining to the first conductor 10A, the aluminum melt penetrates into the melt penetration path 4 during the resistance welding process, so that the volume ratio may be increased by a predetermined length based on the joint surface cs of the joint portion.

Experimentally, before bonding the first conductor 10A and the second conductor 10B, a melt penetration path is formed by a predetermined length on the bonding surface cs2 of the second conductor 10B to form the second conductor 10B. When resistance welding is performed in a state where the volume ratio at a certain length from the joint surface cs2 is reduced to 90% or less, the first conductor 10A and the second conductor 10B are joined, and then the The second conductor volume fraction increasing region 11B can be secured up to a certain length in the direction of the second conductor 10B based on the bonding surface cs, and preferably, the conductor volume of the second conductor volume fraction increasing region 11B The rate can be 98% or higher. In addition, the length of forming the melt penetration path 4 on the bonding surface cs2 of the second conductor 10B is preferably at least 20 millimeters (mm).

Fig. 10 shows a state in which a pair of copper conductors as the first conductors 10A and aluminum conductors as the second conductors 10B are respectively mounted on a welding jig j, and Fig. 11 shows the first conductors 10A. and a process of joining the joint surfaces of the second conductor 10B by resistance welding. A state in which the burr (b) is removed and bonding is completed is shown.

As shown in FIG. 10 , the joint surface cs1 and the second conductor of the first conductor 10A in a state where each of the first conductor 10A and the second conductor 10B is mounted on a welding jig j When the bonding surface cs2 of (10B) is brought into contact and energized, the second conductor is melted near the contact surface. At this time, as shown in FIG. 11, when both conductors are pressed in the contact direction, a burr b is formed A dissimilar conductor junction 11 may be formed around the junction surface cs.

As described above, the first conductor 10A is in a state in which the volume ratio of the conductor is high by a certain length, and the melt penetrates so that the volume ratio is lowered by a certain length from the joint surface cs2 of the second conductor 10B. The path 4 is formed.

As a welding method for joining the first conductor 10A and the second conductor 10B shown in FIG. 11 , upset butt welding may be used. Melt resistance welding is a bonding method that uses Joule heat through current flow as a direct heat source for heating the junction area and melting the material. It can consist of a pressing process that compresses once it begins to melt.

According to the present invention, during the resistance welding, the welding temperature is lower than the melting point of the first conductor 10A and resistance welding is performed at a temperature higher than the melting point of the second conductor 10B.

Here, the first conductor 10A hardly melts, but the second conductor 10B is sufficiently melted so that the melt penetration path of the second conductor 10B is formed on the joint surface cs2 of the second conductor 10B ( It is necessary to easily penetrate into 4), and for this, it is important to select an appropriate welding temperature.

When the welding temperature is higher than the melting point of the second conductor 10B, but the difference is not large, the viscosity of the melt is too high, so it is difficult for the melt to easily flow into the melt penetration path, and the welding temperature is too much higher than the melting point of the second conductor 10B If it is high, there is a possibility that the melt may not be maintained in the vicinity of the joint in the form of a burr and will flow down and not sufficiently penetrate into the melt penetration path. From this point of view, the welding temperature is preferably 5% to 15% higher than the melting point of the second conductor 10B to perform resistance welding.

And, as shown in FIG. 10 , the length d1 < d2 of the first conductor 10A and the second conductor 10B exposed in the joining direction in the state mounted on each welding jig j is may be different.

When the first conductor 10A and the second conductor 10B are brought into contact with each other to conduct electricity by the melt-resistance welding method, since the first conductor 10A having a high melting point does not melt, the exposure length d1 of the first conductor 10A ) is shortened, on the other hand, since the second conductor 10B having a low melting point is melted, the exposure length d2 of the second conductor 10B is determined in consideration of the amount of melting for sufficient bonding.

Specifically, the exposure length d2 of the second conductor 10B may be twice or more, preferably, 10 times or more, the exposure length d1 of the first conductor 10A.

The second conductor 10B may be made of aluminum or an aluminum alloy, and since the melting point is lower than that of the first conductor 10A made of copper and the length exposed from the welding jig is larger, the second conductor 10B has a circular shape. Even if it is welded in a compressed conductor state, it can be sufficiently melted and uniformly joined in the dissimilar conductor joint 11 .

In addition, as shown in FIG. 11, the aluminum melt m slowly penetrates into the melt penetration path 4 of the second conductor 10B in the process of performing melt resistance welding, and as shown in FIG. In a state where resistance welding is completed, the inside of the melt penetration path 4 is filled with the aluminum melt m to constitute the dissimilar conductor joint 11 .

Here, the 'heterogeneous conductor junction' refers to a region where the first conductor 10A and the second conductor 10B are joined by recrystallization around the bonding surface cs in the bonding process. may be defined as a dotted line display area including the volume ratio increasing area 11A of the first conductor 10A and the volume ratio increasing area 11B of the second conductor 10B based on .

And, as shown in FIG. 12, the melt penetration path 4 of the second conductor 10B is shortened by the melting of the second conductor 10B as the welding process is performed, but the dissimilar conductor junction 11 The length of the volume ratio increasing region 11B of the second conductor 10B may be longer than the length of the volume ratio increasing region 11A of the first conductor 10A constituting the .

In the dissimilar conductor junction 11, the volume fraction increasing region 11A of the first conductor 10A is formed after welding the first conductor 10A of the same material by resistance welding as described with reference to FIGS. 1 to 3 . It means an area in which the volume ratio is increased by a predetermined length from the joint surface cs1 generated by removing the burr b of the joint portion 11' and cutting the joint portion 11', and the volume of the second conductor 10B In the rate increasing region 11B, the aluminum melt m flows in the direction of the second conductor 10B from the bonding surface cs2 of the second conductor 10B in the bonding process with the first conductor 10A, so that the volume ratio is increased. It can mean an area that has been Here, the volume fraction increasing region 11B of the second conductor 10B is formed to increase the flexural strength of the joint, and as shown in FIGS. 10 to 12 , the melt penetration path 4 in the second conductor 10B Although it has been described that the volume ratio increasing region 11B of the second conductor 10B is formed by forming ), the present invention is not limited thereto.

It is preferable that the volume ratio of the second conductor 10B also increases to about 98% or more in the volume ratio increase region 11B of the second conductor 10B of the dissimilar conductor junction 11, and accordingly, the dissimilar conductor junction ( 11) flexural strength can be increased.

That is, the aluminum melt m penetrated into the melt penetration path 4 and hardened serves as a skeleton connecting the bonding surface cs and the second conductor 10B and at the same time composing the heterogeneous conductor junction 11 It can be understood that the effect of improving the volume ratio of the conductor by a predetermined length in the direction from the bonding surface cs to the second conductor 10B is obtained.

And, when the fusion resistance welding is completed, as shown in FIG. 12 , when the burr b on the outer peripheral surface of the dissimilar conductor junction 11 is removed after the bonding is completed, the dissimilar conductor junction 11 may be completed. In the tensile bending test, in order to prevent damage such as cracks or rupture of the dissimilar conductor joint 11, the volume ratio increase region 11B of the second conductor 10B has a volume ratio of 98% or more under various test conditions, and its length is preferably at least 3mm or more.

In the embodiment with reference to FIGS. 10 to 12, when dissimilar conductors having different melting points are connected, a melt penetration path is formed only in the second conductor 10B having a low melting point, and in the bonding process, the second conductor 10B of the dissimilar conductor junction 11 is formed. By increasing the volume ratio of the conductor, the flexural strength of the dissimilar conductor junction portion 11 was greater than the flexural strength of the second conductor 10B.

However, the method of increasing the volume ratio of the conductor by forming the melt penetration path as described above is applicable to the first conductor having a high melting point as well as the second conductor having a low melting point.

That is, in FIG. 3 , the volume ratio of the conductor is further increased by a predetermined length from the bonding surface cs1 of the first conductor 10A formed by cutting the bonding portion 11 ′, and the first conductor 10A and the second conductor 10A and the second conductor at the bonding surface in FIG. In order to increase the bonding strength between the conductors 10B, before bonding the first conductor 10A and the second conductor 10B, at least one melt infiltrates into the bonding surface cs1 of the first conductor 10A and the inside thereof. path can be formed.

In the melt penetration path, the melt of the second conductor 10B flows in during the bonding process between the first conductor 10A and the second conductor 10B, so that the volume ratio of the volume ratio increase region 11A of the first conductor 10A may play a role in further increasing

In addition, as the melt of the second conductor 10B penetrates between the first conductors 10A through the melt penetration path, the bonding strength between the first conductor 10A and the second conductor 10B at the bonding surface CS increases. rises That is, the aluminum melt penetrated into the melt penetration path of the first conductor 10A and hardened serves as a skeleton connecting the first conductor 10A and the second conductor 10B based on the bonding surface cs, and at the same time It can be easily guessed that the effect of improving the conductor volume ratio by a certain length in the direction of the first conductor 10A from the bonding surface cs constituting the dissimilar conductor junction portion 11 can be obtained.

13 shows a stripped perspective view of a conductor and an XLPE insulation layer applied with a copper or aluminum-based element of the present invention compressed into a circular shape.

13, the power cable 100 is provided with a conductor 10 in the center. The conductor 10 serves as a passage through which current flows, and may be made of, for example, copper (including copper alloy) or aluminum (including aluminum alloy). The conductor 10 may be composed of a circular compression conductor obtained by compressing a plurality of circular elements in a circular shape for flexibility as shown in FIG. 14, but may be composed of a flat conductor as will be described later with reference to FIG. may be

Since the surface of the conductor 10 is not smooth, the electric field may be non-uniform, and partial corona discharge is likely to occur. In addition, if a void is formed between the surface of the conductor 10 and the insulating layer 14 to be described later, the insulating performance may be deteriorated. In order to solve the above problems, an inner semiconducting layer 12 made of a semiconducting material such as semiconducting carbon paper may be provided outside the conductor 10 .

The inner semiconducting layer 12 improves the dielectric strength of the insulating layer 14 to be described later by making the electric field uniform by evening the electric charge distribution on the conductor surface. Furthermore, it is possible to prevent the formation of a gap between the conductor 10 and the insulating layer 14 to prevent corona discharge and ionization.

An insulating layer 14 is provided outside the inner semiconducting layer 12 . In general, the insulating layer 14 has a high breakdown voltage, and insulating performance must be stably maintained for a long period of time. Furthermore, it should have low dielectric loss and resistance to heat such as heat resistance.

The insulating layer 14 of such a power cable is mainly applied with earth insulation or a resin material (XLPE, etc.).

Although the example in which the insulating layer of the power cable shown in FIG. 13 is made of a resin material is described, a ground-insulating insulating layer may be applied.

For the insulating layer 14 made of a resin material, a polyolefin resin such as polyethylene or polypropylene is used, and a polyethylene resin is preferable. The polyethylene resin may be a crosslinking resin and may be prepared by using silane or an organic peroxide, for example, dicumyl peroxide (DCP) as a crosslinking agent.

In addition, an outer semiconducting layer 16 is provided outside the insulating layer 14 . The outer semiconducting layer 16 is grounded and serves to improve the dielectric strength of the insulating layer 14 by making the distribution of electric force lines between the inner semiconducting layer 12 and the above-described inner semiconducting layer into an equipotential potential. In addition, the outer semiconducting layer 16 can smooth the surface of the insulating layer 14 in the cable to relieve electric field concentration and prevent corona discharge.

A metal sheath 18 or the like may be provided on the outside of the outer semiconducting layer 16 depending on the type of cable. The metal sheath 18 may be used as electrical shielding and a return path of a short-circuit current, and the metal sheath 18 may be replaced with a shielding layer configured in the form of a neutral wire.

An outer jacket 20 is provided on the outermost side of the power cable 100 . The outer jacket 20 may be provided on the outermost side of the cable 100 to protect the internal configuration of the power cable 100 . Accordingly, the outer jacket 20 may be generally made of polyvinyl chloride (PVC) or polyethylene (PE).

Such a power cable may be a power cable laid underground or in an underground pipeline. The power cable may be a power cable (hereinafter referred to as 'submarine power cable') installed in water, such as a river or sea, in addition to an underground or underground pipeline. In the case of a submarine power cable, it may have a structure different from that of an underground power cable in order to adapt to the harsh underwater environment and protect the cable.

14 shows a stripped perspective view of a power cable to which a copper or aluminum-based flat conductor and an XLPE insulation layer of the present invention are applied. It is generally similar to the structure of the underground power cable with reference to FIG. 13, but the differences will be mainly described.

Referring to FIG. 14 , the power cable 100 includes a conductor 10 , an inner semiconducting layer 12 , an insulating layer 14 , and an outer semiconducting layer 16 in the cable length direction along the conductor 10 . Only the electric power is transmitted, and the cable core portion A is provided to prevent current leakage in the radial direction of the cable.

The conductor 10 serves as a path through which electric current flows to transmit power, and has excellent conductivity to minimize power loss and is a material having strength and flexibility suitable for manufacturing and using cables, for example, copper (copper alloy). included) or aluminum (including aluminum alloy).

As shown in FIG. 11, the conductor 10 includes a flat wire layer 1C consisting of a circular central wire 1a and a flat wire 1b twisted to surround the circular central wire 1a, It may be a flat conductor 10 having a circular cross section as a whole.

As another example, as shown in FIG. 13 , the conductor 10 may be a circular compression conductor in which a plurality of circular element wires are twisted and compressed into a circular shape.

The flat conductor 10 has a relatively high volume ratio compared to the circular compressed conductor shown in FIG. 13 , so that the outer diameter of the cable can be reduced.

An inner semiconducting layer 12 may be formed outside the conductor 10 , and an insulating layer 14 may be provided outside the inner semiconducting layer 12 . The insulating layer 14 may be made of earth insulation or a resin material, but the submarine power cable 100 of the present invention shown in FIG. 14 is also made of XLPE material like the underground power cable shown in FIG. 13 . do.

An outer semiconducting layer 16 may be provided on the outside of the insulating layer 14, and a water absorption part 17 for preventing moisture from penetrating into the cable may be provided outside the outer semiconducting layer 16. have. The moisture absorbing part 17 may be formed between the stranded strands of the conductor 10 and/or outside the conductor 10, and the speed of absorbing moisture penetrating into the cable is high, and the absorption state is maintained. It is composed in the form of powder, tape, coating layer or film containing super absorbent polymer (SAP), which has excellent water absorption ability, and plays a role in preventing moisture from penetrating in the longitudinal direction of the cable. In addition, the moisture absorbing part may have semi-conductivity to prevent a sudden change in the electric field.

In addition, the moisture absorption unit 17 may be provided together with a copper wire straight-through tape (not shown). The copper wire straight-through tape is composed of a copper wire and a non-woven tape and acts to facilitate electrical contact between the outer semiconducting layer 16 and the metal sheath 18, and the moisture absorption layer 17 penetrates the cable. It is composed of powder, tape, coating layer or film containing super absorbent polymer (SAP), which absorbs moisture quickly and has excellent ability to maintain absorption, so that moisture penetrates in the longitudinal direction of the cable. serves to prevent In addition, the copper wire straight-through tape and the moisture absorbing layer 17 preferably have semi-conductive properties to prevent a sudden electric field change, and include a copper wire in the moisture absorbing layer 17 to conduct both conduction and moisture absorption. You may.

A cable protection part (B) is provided on the outside of the cable core part (A) configured as described above, and the submarine power cable 100 installed on the seabed may additionally include a cable sheath part (C). The cable protection part (B) and the cable sheath part (C) protect the core part (A) from various environmental factors such as moisture penetration, mechanical trauma, and corrosion that may affect the power transmission performance of the cable.

The cable protection unit B includes a metal sheath 18 and a polymer sheath 20 to protect the cable from fault current, external force, or other external environmental factors.

The underground power cable shown in FIG. 13 has been described as having a structure in which a cable jacket is provided outside the metal sheath, but the polymer sheath 20 is provided outside the metal sheath 18 of the submarine power cable shown in FIG. 14 . can be understood

In particular, the metal sheath 18 constituting the submarine power cable may be formed to surround the core portion 10 for the purpose of shielding, grounding, or sealing. In particular, when the power cable 100 is installed in an environment such as the seabed, it can be formed to seal the cable core part (A) to prevent foreign substances such as moisture from entering the cable core part (A). In addition, by extruding the molten metal to the outside of the cable core part (A) to have a seamless and continuous outer surface, it is possible to have excellent water-repellent performance. Lead or aluminum is used as the metal, and in the case of the power cable 100 laid on the seabed, it is preferable to use lead with excellent corrosion resistance to seawater, and a metal element is added to supplement the mechanical properties. It is more preferable to use one lead alloy. In addition, the metal sheath 18 is grounded at the end of the power cable 100 to serve as a path through which an accident current flows in the event of an accident such as a ground fault or short circuit, and protects the cable from external impact, and the electric field is not discharged to the outside of the cable. can prevent it

In addition, the metal sheath 18 may be coated with an anti-corrosion compound, for example, blown asphalt, etc. on the surface of the metal sheath 18 to further improve corrosion resistance, water resistance, etc. can

The polymer sheath 20 is formed outside the metal sheath 18 to improve corrosion resistance and water resistance of the cable, and to protect the cable from mechanical trauma and other external environmental factors such as heat and ultraviolet rays. can The polymer sheath 20 may be formed of a resin such as polyvinyl chloride (PVC), polyethylene, etc., and in the case of the power cable 100 to be laid on the seabed, it is preferable to use a polyethylene resin having excellent water resistance, and flame retardancy. In this demanding environment, it is preferable to use a polyvinyl chloride resin.

The power cable 100 is provided with a metal steel strip layer 21 made of galvanized steel tape or the like on the outside of the polymer sheath 20, and the metal sheath 18 is expanded by the expansion of the insulating oil. can be prevented from doing In addition, a bedding layer (not shown) made of a semi-conductive non-woven tape or the like and buffering an external force applied to the power cable 100 may be provided on the upper and/or lower portion of the metal steel strip layer 21 , and polyvinyl chloride to further improve the corrosion resistance, water resistance, etc. of the power cable 100 by further providing an outer sheath 22 made of a resin such as polyethylene, and additionally protect the cable from mechanical trauma and other external environmental factors such as heat and ultraviolet rays It can function as a cable protection part (B).

In addition, the power cable 100 installed on the seabed is easily injured by the anchor of a ship, etc., and may be damaged by bending force caused by ocean currents or waves, frictional force with the seabed, etc., so to prevent this, the cable protection part (B ) may be additionally provided with a cable sheath (C) on the outside.

The cable sheath (C) may include a metal armor layer (34) and a serving layer (38). The metal armor layer 34 is made of steel, galvanized steel, copper, brass, bronze, etc. and can be composed of at least one layer or more by transversing a wire having a cross-sectional shape such as a circular shape or a flat shape, and the power cable 100 ) not only serves to enhance the mechanical properties and performance of the product, but also additionally protects the cable from external forces.

The serving layer 38 composed of polypropylene yarn, etc. is formed in one or more layers above and/or below the metal armor layer 34 to protect the cable, and the serving layer 38 formed at the outermost portion is It is composed of two or more materials with different colors to ensure visibility of cables laid on the seabed.

In the case of laying such power cables, intermediate connections may be performed at intervals of several hundred meters or several kilometers.

15 is a cross-sectional view of an intermediate connection structure of a power cable according to an embodiment of the present invention.

The intermediate connection structure shown in FIG. 15 may be a factory connection structure or a flexible connection structure mainly used for submarine power cables and the like.

That is, the intermediate connection of the power cables (100A, 100B) is performed not at the power cable installation site, but at the power cable factory, etc., and then wound on a bobbin or turntable, etc., and transported to the installation site. can save

The conductors of a pair of power cables connected by such a power cable connection structure 300 may be heterogeneous conductors.

For example, the first conductor 10A of the first power cable 100A may be a copper conductor, and the second conductor 10B of the second power cable 100B may be composed of an aluminum conductor.

Such a factory connection structure may configure the intermediate connection structure through a restoration layer in which the internal configuration of the intermediate connection structure is restored similarly to the internal structure of both power cables without applying a housing-type enclosure.

That is, as described above, the pair of first conductors 10A and second conductors 10B increase the volume ratio of the first conductor 10A and decrease the volume ratio of the second conductor 10B at the bonding surface. Melt resistance welding may be performed to form a dissimilar conductor junction, and an inner semiconducting restoration layer 12' is formed using a semiconducting tube on the outside of the conductor junction 11, and the inner semiconducting restoration layer 12' XLPE tape or insulating paper is wound on the outside to interconnect the insulation layers of both power cables to form an insulation restoration layer 14', which restores the insulation layer, and similarly to the inner semi-conduction restoration layer 12', the insulation restoration layer outside The outer semiconducting restoration layer 16' may be formed by using a semiconducting tube in the (14').

In addition, the metal sheath of the power cable is connected, and a metal sheath restoration layer 18 is formed using a lead tube or the like for shielding, blocking, or sealing, and an external sheath is formed on the outside of the metal sheath restoration layer 18'. The restoration layer 20' may be restored, and, if necessary, a metal steel band restoration layer and an exterior restoration layer may be further configured.

In the case of such a factory connection structure, when it is installed in an underwater environment such as the seabed, it is continuously exposed to bending, and tensile force is continuously applied under the influence of currents, etc., so it is necessary to secure sufficient flexural strength of the conductor joints constituting the intermediate connection structure. .

Therefore, as described above, the first conductor 10A made of copper of the first power cable increases the volume ratio by a predetermined length, and the second conductor 10B made of aluminum of the second power cable has a predetermined length from the bonding surface. During melt resistance welding by lowering the volume ratio as much as possible, the melt having a lower melting point than the first conductor 10A flows into the melt penetration path formed on the joint surface of the second conductor 10B to fill the empty space of the second conductor, and the As a result, as described above, the volume ratio of the second conductor 10B can be increased and the flexural strength can be improved accordingly.

In the heterogeneous conductor junction shown in FIGS. 1 to 15, the conductors of both power cables are of different types, but have the same diameter as an example. Since the diameter of the conductor is the same, the power cable provided with copper, which is the first conductor 10A, generates less heat and has a large current carrying capacity, but heat generation is not a major problem in the submarine section of the cables connecting the land section and the seabed section. In the case of arranging power cables to which aluminum-based conductors are applied in the seabed section and power cables to which copper-based conductors are applied in the land section, and intermediate connection in the boundary area, both cost reduction and stability improvement can be obtained.

However, in addition to the above special boundary area, it is necessary to intermediately connect both power cables having a pair of different conductors. There are times when you have to

Specifically, the diameters of the first conductor 10A, which is a copper conductor, and the second conductor 10B, which is an aluminum conductor, may be different due to the conduction ability or heat generation.

The present invention can provide a heterogeneous conductor junction that can be applied even when the first conductor 10A and the second conductor 10B have different diameters (different diameter and different conductors). With reference to FIGS. 16 and 17, a connection structure of a different diameter and a different conductor and an intermediate connection structure of a power cable including the same will be described.

16 is a cross-sectional view of an intermediate connection structure of a power cable according to an embodiment of the present invention, and FIG. 17 is a perspective view of a dissimilar conductor junction applicable to the intermediate connection structure of the power cable shown in FIG. 16 .

Referring to FIG. 16 , the intermediate connection structure 300 includes first and second conductors 10A and 10B of a pair of first and second power cables 100A and 100B, and the first An O-ring 30 bonded together to the ends of the conductor 10A and the second conductor 10B, and the insulating layers 14A and 14B of the pair of the first power cable 100A and the second power cable 100B ) and a corona shield 320 configured to surround the heterogeneous conductor junction and the pair of first power cables 100A and second power cables 100B, wrapped around the outside and made of an elastic resin material that can be contracted at room temperature and may include a sleeve member 360 in the form of a pre molded joint (PMJ). The sleeve member 360 may have a hollow shape.

The corona shield 320 is formed to extend from the insulating layer 14A of the first power cable 100A toward the insulating layer 14B of the second power cable 100B. In this case, the corona shield 320 has a flat outer surface, is configured to surround the O-ring 30, and is continuous without a step with the surfaces of a pair of insulating layers 14A and 14B facing both sides. A surface is formed to prevent or mitigate electric field concentration, and a corona that may occur between a pair of first conductors 10A and second conductors 10B and the sleeve member 360 connected by an O-ring 30 . discharge can be prevented.

In an embodiment of the present invention, since a pair of cables 100A and 100B having different diameters are connected to each other, the corona shield 320 is also configured in a structure with different diameters on both sides, and the outside has a relatively large diameter of the second power The cable 100B may have a structure inclined toward the first power cable 100A having a relatively small diameter.

The sleeve member 360 is provided on the outside of the corona shield 320 and is made of a copper material and has a first end 330A into which the end of the first power cable 100A having a relatively small conductor diameter is inserted; A first electrode 330 made of aluminum and having a second end 330B into which an end of a second power cable 100B having a relatively large diameter is inserted, and spaced apart from the first electrode 330 to face A pair of second electrodes 340 and an insulating layer of the first electrode 330, the second electrode 340 and the pair of the first power cable 100A and the second power cable 100B provided A sleeve insulating layer 350 surrounding 14A and 14B may be included. The sleeve insulating layer 350 may be formed of Ethylene Propylene Diene Monomer (EPDM) or Liquid Silicon Rubber (LSR).

The first electrode 330 is made of a semiconducting material and is electrically connected to the first conductor 10A and the second conductor 10B of the power cable, and serves as a so-called high-voltage electrode. The second electrode 340 is also made of a semiconducting material and is connected to the outer semiconducting layers 16A and 16B of the power cable to serve as a so-called shielding electrode (Deflector). Accordingly, the electric field distribution inside the intermediate junction box 300 is distributed along between the first electrode 330 and the second electrode 340, and the first electrode 330 and the second electrode 340 are In between, the electric field is not locally concentrated, but serves to spread evenly.

At this time, the distance D1 from the center of the cable at the position of the first end 330A to the outer surface of the first electrode 330 and the distance D2 from the center of the second end 330B to the outer surface are equal to each other, and the respective distances L1 and L2 from each center to the inner surface at the first end 330A and the second end 330B, and the respective first and second power cables 100A and 100B ), the distances P1 and P2 from the surfaces of the insulating layers 14A and 14B to the outer surfaces may be configured to be different from each other.

The first conductor 10A and the second conductor 10B have different materials and diameters, and accordingly, the insulating layers 14A and 14B of the first power cable 100A and the second power cable 100B from the center of the cable. Although the distance to the outer circumferential surface is different, the respective distances L1 and L2 from the respective centers of the first and second ends 330A and 330B to the inner surfaces and the respective first power cables 100A and the second power cables By varying the distances P1 and P2 from the surface to the outer surface of the insulating layers 14A, 14B of 100B, the first electrode 330 is connected from the center of the cable at the position of the first end 330A to the outer surface. The distance D1 of , may match the distance D2 from the center of the second end 330B to the outer surface.

Furthermore, the intermediate connection structure 300 includes an enclosure member 200 formed of a so-called 'coffin box' or a 'metal casing' surrounding the sleeve member 360 . At this time, the space between the housing 200 and the sleeve member 360 may be filled with a waterproofing material (not shown).

Even when the diameter of the connected conductor or the outer diameter of the power cable is different, the difference is that the O-ring 30 is applied to relieve the concentration of electric field near the conductor junction, but the copper material of the first power cable The volume ratio is increased by a certain length from the joint surface of the first conductor 10A of The molten material of the conductor flows into the melt penetration path formed on the joint surface of the second conductor 10B and fills the empty space of the second conductor, thereby increasing the volume ratio of the second conductor 10B, thereby improving the flexural strength. is the same

16 is an example of a pair of power cables having different types and diameters of conductors, and has been described with an intermediate connection structure for connecting power cables having an insulating layer made of XLPE material. The connected power cable may be a ground-insulated cable.

That is, the dissimilar conductor junction and dissimilar conductor connection method of the present invention with reference to FIGS. 1 to 16 can be applied to the connection of the above-mentioned copper conductor and the connection of the dissimilar conductor to which the O-ring is bonded together, and the power cable connected in the middle In addition to the intermediate connection structure in which the corona shield and sleeve member are mounted on the outside of the dissimilar conductor junction according to the type of insulation layer of It can be applied to an intermediate connection structure having It can also be applied to a flexible factory or flexible connection structure.

As described above, in the case of intermediate connection of power cables composed of dissimilar conductors such as copper and aluminum, in order to solve problems of current carrying capacity or heat generation, conductors and cables may have different diameters. Hereinafter, a method for intermediately connecting a pair of power cables composed of different diameters and different conductors will be reviewed.

With reference to the drawings, the order of connecting a pair of first power cables (100A) and second power cables (100B) having different conductor diameters to each other by the intermediate junction box (300) and the intermediate connection structure (300) Let's take a look at it in detail.

Referring to FIG. 17 , an O-ring 30 may be provided to surround the dissimilar conductor junction part 11 in order to bond the different mirrors and the dissimilar conductors.

The O-ring 30 is mounted with the first conductor 10A inserted therein, the maximum outer diameter of the O-ring 30 coincides with the outer diameter of the second conductor 10B, and the minimum outer diameter (through hole diameter) is It may be configured to match the outer diameter of the first conductor 10A.

Therefore, when melt resistance welding is completed in the state in which the O-ring 30 is mounted, the side of the maximum outer diameter portion B of the O-ring 30 is at the bonding surface cs2 of the second conductor 10B. is bonded, and the inner peripheral surface of the through hole of the O-ring 30 may be joined to the outer peripheral surface of the first conductor 10A.

Accordingly, the diameter of the through hole of the O-ring 30 is preferably configured to correspond to the diameter of the first conductor 10A.

With this structure, the bonding surfaces of the first conductor 10A and the second conductor 10B, which are different diameters and different conductors, are bonded, and at the same time, the inner peripheral surface of the through hole and the bonding surface of the O-ring 30 are respectively first The outer peripheral surface of the conductor 10A and the second conductor 10B may be joined to the joint surface cs2 to be integrated.

The O-ring 30 compensates for the difference in diameter between the second conductor 10B of the second power cable 100B and the first conductor 10A of the first power cable, and the step difference in the dissimilar conductor junction 11 is It may be provided for the purpose of removing Accordingly, the cross section of the O-ring 30 may be configured in a right-angled triangle or tapered shape, respectively. The O-ring 30 has a tapered outer circumferential surface, so that it is possible to remove a step difference at the dissimilar conductor junction 11 between the first conductor 10A and the second conductor 10B, and to reduce electric field concentration at the step difference, etc. can be prevented or mitigated.

The material of the O-ring 30 may be the same as that of the first conductor 10A or the second conductor 10B, but preferably the same material as that of the second conductor 10B with a low melting point. can be composed of

18 to 20 show a conductor bonding process of the dissimilar conductor junction shown in FIG. 17 .

The conductor bonding process of the dissimilar conductor junction shown in FIGS. 18 to 20 is the same as that of the dissimilar conductor with reference to FIGS. 1 to 12, except that an O-ring 30 is applied to relieve the concentration of electric field at the dissimilar conductor junction 11. It is the same as the conductor bonding process.

That is, even when the diameter of the conductor to be connected or the outer diameter of the power cable is different, the O-ring 30 is applied to relieve the concentration of the electric field in the vicinity of the dissimilar conductor junction 11, but FIGS. 1 to As shown in FIG. 6, before bonding of the first conductor 10A and the second conductor 10B, the volume ratio by a certain length from the bonding surface cs1 of the first conductor 10A made of copper of the first power cable. 7 to 10, lower the volume ratio by a method of forming a melt penetration path by a certain length from the joint surface cs2 of the second conductor 10B made of aluminum of the second power cable During melt resistance welding, the molten material of the second conductor having a lower melting point than that of the first conductor 10A flows into the melt penetration path formed on the joint surface cs2 of the second conductor 10B, and fills the empty space of the second conductor. It is also possible to increase the volume ratio of the two conductors 10B and thereby improve the flexural strength.

Accordingly, the description overlapping with the bonding process of dissimilar copper conductors with reference to FIGS. 1 to 12 will be omitted.

18, when the first conductor 10A and the second conductor 10B having different diameters are mounted on the welding jigs j' and j'', at the end of the first conductor 10A, An O-ring (30) can be mounted. Accordingly, the welding jig j ′ shown in FIG. 18 may be configured to include an O-ring 30 receiving portion so as to mount the first conductor 10A on which the O-ring 30 is mounted. .

In addition, the O-ring 30 is made of the same aluminum-based material as the second conductor 10B with a low melting point. It can be configured to be melted and recrystallized together with 10B) to be bonded. A method of forming the O-ring 30 with the same copper-based metal as that of the first conductor 10A is also possible, but the O-ring 30 and the inner peripheral surface of the through-hole of the O-ring 30 and the through-hole In order to improve the bondability with the first conductor 10A inserted into the , the O-ring 30 is preferably made of a material of the second conductor 10B having a low melting point.

The first conductor 10A, the second conductor 10B, and the hetero-conductor junction 11 of the O-ring 30 joined in this way are first connected to the second conductor 10B as shown in FIG. 20 . The bonding may be completed in the form in which the end of the conductor 10A is inserted, and the outer circumferential surface of the dissimilar conductor junction 11 is replaced with the outer circumferential surface of the O-ring 30 to be composed of an inclined surface, not a step, despite being a different diameter conductor. can

As described above, the outer diameter at the minimum outer diameter portion (x) of the outer peripheral surface of the O-ring 30 coincides with the outer diameter of the first conductor 10A, and the outer diameter at the maximum outer diameter portion (y) is the The step difference in the heterogeneous conductor junction 11 that may be caused by the difference in diameter between the first conductor 10A and the second conductor 10B, which is identical to the outer diameter of the second conductor 10B and has a different diameter, is made into a gentle slope. This has the effect of alleviating problems such as electric field concentration. Also, the volume ratio and flexural strength of the second conductor 10B may be improved by introducing the aluminum melt into the melt penetration path formed on the joint surface of the second conductor 10B during the melt resistance welding process.

In addition, the O-ring 30 is recrystallized in the melt-resistance welding process, surrounds the vicinity of the junction of the first conductor, and is connected to the aluminum conductor in the melt penetration path that serves as a skeleton inside the second conductor through the junction surface. As a result, tensile flexural strength can be further improved.

21 shows a three-point bending test, which is a test method that can confirm flexural strength. 22 shows an image of a three-point bending test result of a dissimilar conductor joint joined by a dissimilar conductor bonding method according to the present invention.

In the three-point bending test shown in FIG. 21, after the specimen is mounted on the first and third rollers r1 and r3, the second roller r2 is placed in contact with the specimen, and the second roller While moving (r2) down, the load is recorded at predetermined time intervals, and the test is stopped when the specimen breaks or the applied load falls beyond the highest point. way you can do it

For example, according to the test conditions described in ISO 7438 Metallic materials bend test, the distance L of rollers 1 and 3 is 240 mm, the diameter (D) of roller 2 is 100 mm, and the diameter of the specimen (d) is 48 mm on average, , the descending speed (V) of the second roller (r2) may be 10 mm/min, and the test conditions can be changed within an appropriate range.

Specifically, the specimen shown in FIG. 22 is a result of testing according to a three-point bending test. The specimen may include a dissimilar conductor junction 11, a first conductor 10A that is a copper conductor, and a second conductor 10B that is an aluminum conductor, and the first conductor 10A has a volume ratio by a predetermined length from the junction surface. The height is pre-processed, and the second conductor 10B is subjected to pre-processing to lower the volume ratio by forming a melt penetration path as shown in FIG. As the joint structure of (10A) and the second conductor 10B, it is a joint structure in which the volume ratio of the first conductor 10A and the second conductor 10B is increased.

As a result of performing a three-point bending test as shown in FIG. 22, the first conductor 10A and the dissimilar conductor junction 11 made of copper have a relatively low melting point before damage such as deformation, fracture, or crack occurs. As an example of the deformation pd in the two conductors 10B, the wire splay occurred. The fact that the deformation occurred in the second conductor 10B to which a load smaller than the load applied to the dissimilar conductor junction 11 occurred means that the flexural strength of the dissimilar conductor junction 11 was relatively higher than that of the second conductor 10B. .

In general, a conductor is designed to have sufficient flexural strength in a harsh environment such as a seabed environment. The fact that the heterogeneous conductor junction 11 has a relatively higher flexural strength than the second conductor 10B means that the dissimilar conductor junction 11 It can be seen that sufficient flexural strength was secured.

Through these test results, the first conductor 10A processed to increase the volume fraction of the conductor by a certain length from the joint surface cs1 and the first conductor 10A processed to decrease the volume fraction by a certain length from the joint surface cs2, the first conductor ( When the second conductor 10B, which has a lower melting point than 10A), is joined at a temperature lower than the melting point of the first conductor 10A and higher than the melting point of the second conductor 10B by the method of melting resistance welding, the dissimilar conductor junction 11 ), it can be seen that the bending strength of the second conductor 10B is greater than that of the second conductor 10B. Also, due to the characteristics of the material, it can be seen that the flexural strength of the dissimilar conductor junction portion 11 is smaller than the flexural strength of the first conductor 10A.

Therefore, when a power cable having a dissimilar conductor is connected, the volume ratio of the volume ratio increase region 11A of the first conductor 10A and the volume ratio of the second conductor 10B with respect to the bonding surface cs at the dissimilar conductor junction part When sufficient flexural strength is secured by forming the increase region 11B, it is possible to solve problems of damage such as deformation, fracture, and cracks occurring at the dissimilar conductor junction.

Although the present specification has been described with reference to preferred embodiments of the present invention, those skilled in the art can variously modify and change the present invention without departing from the spirit and scope of the present invention as set forth in the claims described below. will be able to carry out Therefore, if the modified implementation basically includes the elements of the claims of the present invention, all of them should be considered to be included in the technical scope of the present invention.

4: melt penetration path
10A: first conductor
100A: first power cable
11: conductor joint
10B: second conductor
100B: second power cable
30 : O-ring
300: intermediate connection structure

Claims (36)

A power cable system comprising a first power cable including a first conductor, a second power cable including a second conductor, and a cable connection structure for connecting the first power cable and the second power cable,
The first power cable includes a first conductor made of a plurality of wires,
The second power cable is made of a plurality of wires and includes a second conductor of a material different from that of the first conductor,
the melting point of the first conductor is greater than the melting point of the second conductor;
The cable connection structure includes a dissimilar conductor junction part joined to the first conductor and the second conductor,
The dissimilar conductor junction includes a first conductor volume fraction increasing region and a second conductor volume fraction increasing region,
The first conductor volume ratio increasing region is formed by performing preliminary processing of the first conductor to increase the volume ratio by a predetermined length from the joint surface cs1 of the first conductor, and the second conductor volume ratio increasing region is Power cable system, characterized in that the first conductor and the second conductor are formed by resistance welding after performing preliminary processing of the second conductor to lower the volume ratio by a predetermined length from the joint surface (cs2) of the two conductors. According to claim 1,
The preliminary processing of the first conductor is a power cable system, characterized in that after joining a pair of first conductors by welding, cutting the joint portion and configuring the cut surface as the joint surface (cs1) of the first conductor. 3. The method of claim 2,
Power cable system, characterized in that the volume ratio of the first conductor is 98% or more by a predetermined length from the joint surface (cs1) of the first conductor by the preliminary processing of the first conductor. According to claim 1,
The first conductor is made of copper or a copper alloy material, and the second conductor is made of aluminum or an aluminum alloy material. According to claim 1,
The power cable system, characterized in that the preliminary processing of the second conductor forms a melt penetration path in the longitudinal direction of the second conductor from the bonding surface (cs2) of the second conductor before bonding the first conductor and the conductor. 6. The method of claim 5,
Power cable system, characterized in that the volume ratio of the second conductor by a predetermined length from the joint surface (cs2) of the second conductor by the preliminary processing of the second conductor is 90% or less. 6. The method of claim 5,
The power cable system, characterized in that the melt penetration path is formed by drilling a plurality of points of the joint surface (cs2) of the second conductor using a drill. 6. The method of claim 5,
The melt penetration path is formed by cutting and removing a portion of the plurality of strands constituting the second conductor using a cutting tool from the joint surface (cs2) of the second conductor. According to claim 1,
The volume ratio of the volume ratio increasing region of the second conductor is 98% or more from the joint surface (cs) to at least 3 mm in the longitudinal direction of the second conductor. According to claim 1,
A power cable system having a dissimilar conductor junction, characterized in that the diameter of the first conductor is smaller than the diameter of the second conductor. 11. The method of claim 10,
The dissimilar conductor junction is a power cable system having a dissimilar conductor junction, characterized in that an O-ring with an inclined outer circumferential surface is joined together to close the step difference due to the difference in diameter between the first conductor and the second conductor with an inclined surface. . According to claim 1,
The dissimilar conductor junction part is a power cable system, characterized in that the first conductor and the second conductor are joined by resistance welding. According to claim 1,
The power cable system, characterized in that the first conductor or the second conductor is a circular compression conductor. According to claim 1,
The power cable system, characterized in that the first conductor or the second conductor is a flat conductor. A power cable system comprising a first power cable including a first conductor, a second power cable including a second conductor, and a cable connection structure for connecting the first power cable and the second power cable,
The first power cable includes a first conductor made of a plurality of wires,
The second power cable is made of a plurality of wires and includes a second conductor of a material different from that of the first conductor,
the melting point of the first conductor is greater than the melting point of the second conductor;
The cable connection structure includes a dissimilar conductor junction part joined to the first conductor and the second conductor,
The dissimilar conductor junction includes a volume ratio increasing region of the first conductor and a volume ratio increasing region of the second conductor with respect to the junction surface (cs),
The power cable system, characterized in that the flexural strength of the dissimilar conductor junction is greater than the flexural strength of the second conductor. 16. The method of claim 15,
The volume ratio of the volume ratio increasing region of the second conductor is 98% or more from the joint surface (cs) to at least 3 mm in the longitudinal direction of the second conductor. 16. The method of claim 15,
The first conductor is made of copper or a copper alloy material, and the second conductor is made of aluminum or an aluminum alloy material. 16. The method of claim 15,
A power cable system having a dissimilar conductor junction, characterized in that the diameter of the first conductor is smaller than the diameter of the second conductor. 19. The method of claim 18,
The dissimilar conductor junction is a power cable system having a dissimilar conductor junction, characterized in that an O-ring with an inclined outer circumferential surface is joined together to close the step difference due to the difference in diameter between the first conductor and the second conductor with an inclined surface. . 16. The method of claim 15,
The dissimilar conductor junction part is a power cable system, characterized in that the first conductor and the second conductor are joined by resistance welding. 16. The method of claim 15,
The volume ratio increasing region of the first conductor is a power cable system, characterized in that the volume ratio is processed to be high by a predetermined length in advance before welding between the first conductor and the second conductor. 22. The method of claim 21,
Power cable system, characterized in that the first conductor is processed so that the volume ratio is 98% or more by a certain length from the bonding surface (cs1) of the first conductor before bonding with the second conductor. 22. The method of claim 21,
In the method of processing the first conductor with a volume ratio higher than a predetermined size by a certain length from the joint surface cs1 of the first conductor, after joining a pair of first conductors by welding, the joint portion is cut and the cut surface is Power cable system, characterized in that it is composed of the bonding surface (cs1) of the first conductor. 16. The method of claim 15,
Before joining the first conductor and the second conductor, a melt penetration path is formed in the longitudinal direction of the second conductor from the bonding surface (cs2) of the second conductor, and the second conductor is processed so that the volume ratio is less than or equal to a predetermined size A power cable system that features. 25. The method of claim 24,
Power cable system, characterized in that the volume ratio of the second conductor is processed to be 90% or less. 25. The method of claim 24,
The power cable system, characterized in that the melt penetration path is formed by drilling a plurality of points of the joint surface (cs2) of the second conductor using a drill. 25. The method of claim 24,
The melt penetration path is formed by cutting and removing a portion of the plurality of strands constituting the second conductor using a cutting tool from the joint surface (cs2) of the second conductor. 16. The method of claim 15,
The power cable system, characterized in that the first conductor or the second conductor is a circular compression conductor. 16. The method of claim 15,
The power cable system, characterized in that the first conductor or the second conductor is a flat conductor. A power cable connection method for connecting a first power cable including a first conductor made of a plurality of circular wires and a second power cable including a second conductor comprising a plurality of circular wires made of a material different from the first conductor,
A preliminary processing step of the first conductor by processing the volume ratio higher than a predetermined size by a predetermined length from the joint surface (cs1) of the first conductor;
a pre-processing step of processing a second conductor with a volume ratio lower than a predetermined size by a predetermined length from the joint surface (cs2) of the second conductor; and,
and a resistance welding step of forming a dissimilar conductor junction by joining the bonding surface (cs1) of the first conductor and the bonding surface (cs2) of the second conductor by resistance welding. 31. The method of claim 30,
The resistance welding step is performed by passing a current through the first conductor and the second conductor to melt the first conductor and the second conductor and pressurize the first conductor and the second conductor. . 31. The method of claim 30,
In the resistance welding step, the exposed length of the first conductor in the welding jig for welding the first conductor and the second conductor is smaller than the exposed length of the second conductor. How to connect. 31. The method of claim 30,
In the preliminary processing step of the first conductor, a junction is formed by joining a pair of first conductors by welding such that the volume ratio is 98% or more by a predetermined length from the junction surface of the first conductor cs1, and the junction is cut A power cable connection method, characterized in that it is carried out in a way that the cut surface becomes the bonding surface (cs1) of the first conductor. 31. The method of claim 30,
The pre-processing step of the second conductor is performed from the bonding surface cs2 of the second conductor before bonding the first conductor and the conductor so that the volume ratio is less than or equal to 90% by a certain length from the bonding surface cs2 of the second conductor. A method for connecting a power cable having a dissimilar conductor, characterized in that it is performed by a method of forming a melt penetration path by a predetermined length in the longitudinal direction of the second conductor. 31. The method of claim 30,
After the resistance welding step, the volume ratio of the volume ratio increasing region of the second conductor constituting the dissimilar conductor junction is 98% or more from the junction surface (cs) to at least 3 mm in the longitudinal direction of the second conductor. How to connect. 31. The method of claim 30,
The welding temperature during resistance welding is lower than the melting point of the first conductor and 5% to 15% higher than the melting point of the second conductor.

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