Three-phase combined shielding type plug-in lightning arrester

Abstract

The utility model belongs to the field of lightning arresters, and particularly relates to a three-phase combined shielding type plug-in lightning arrester. One structure of the lightning arrester comprises an A-phase lightning arrester, a B-phase lightning arrester, a C-phase lightning arrester, a shielding shell and a grounding lightning arrester D, the two ends of the A-phase lightning arrester, the two ends of the B-phase lightning arrester and the two ends of the C-phase lightning arrester are provided with wire inlet ends and wire outlet ends respectively. The A-phase lightning arrester, the B-phase lightning arrester and the C-phase lightning arrester are arranged on the shielding shell at intervals and are respectively matched and connected with three plug-in type connecting sleeves in an external switch cabinet, and wire outlet ends are arranged in the shielding shell; the grounding lightning arrester D is mounted in the shielding shell; the wire outlet ends of the A-phase lightning arrester, the B-phase lightning arrester and the C-phase lightning arrester are short-circuited and then are connected with the wire inlet end of the grounding lightning arrester D; and the wire outlet end of the grounding lightning arrester D is grounded. According to the utility model, system phase-to-ground overvoltage protection can be realized, and system phase-to-phase overvoltage protection can also be realized.

Description

Technical Field

[0001] The utility model relates to a lightning arrester, in particular to a three-phase combined shielded plug-in lightning arrester. Background Art

[0002] With the increasing use of C-GIS gas-insulated switchgear and ring main units in the power industry, the demand for shielded plug-in lightning arresters is also increasing.

[0003] However, the currently available shielded plug-in lightning arresters on the market usually only have the overvoltage protection function between the phase and ground, and do not have the inter-phase overvoltage protection function. Especially in the non-effectively grounded neutral system of 35 kV and below, once a single-phase grounding fault occurs, while the overvoltage between the phase and ground appears, the inter-phase overvoltage will also occur. At this time, the ordinary shielded plug-in lightning arrester can only limit the overvoltage between the phase and ground of the system, but cannot limit the inter-phase overvoltage of the system, which is likely to cause the breakdown and damage of the inter-phase insulation of the system, seriously threatening the operation safety of the power system. Summary of the Utility Model

[0004] The purpose of the utility model is to solve the problem that the existing shielded plug-in lightning arrester does not have the inter-phase overvoltage protection function, cannot effectively limit the inter-phase overvoltage of the system, and protect the inter-phase insulation safety of the power system, and provide a three-phase combined shielded plug-in lightning arrester.

[0005] To achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0006] A three-phase combined shielded plug-in lightning arrester, characterized in that:

[0007] It includes a phase A lightning arrester, a phase B lightning arrester, a phase C lightning arrester, a shielding housing, and a grounding lightning arrester D;

[0008] Both ends of the phase A lightning arrester, the phase B lightning arrester, and the phase C lightning arrester are respectively provided with an incoming line end and an outgoing line end;

[0009] The phase A lightning arrester, the phase B lightning arrester, and the phase C lightning arrester are installed on the shielding housing at intervals, and their incoming line ends are all plug-in joints, which are respectively matched and connected with three plug-in connection bushings in the external switchgear, and the outgoing line ends are placed inside the shielding housing;

[0010] The grounding lightning arrester D is installed inside the shielding housing. The outgoing line ends of the phase A lightning arrester, the phase B lightning arrester, and the phase C lightning arrester are short-circuited to form a neutral point, and the neutral point is connected to the incoming line end of the grounding lightning arrester D;

[0011] The outgoing line end of the grounding lightning arrester D is led out of the shielding housing and then grounded; or, the outgoing line end of the grounding lightning arrester D is connected to the inner wall of the shielding housing, and the outer wall of the shielding housing is grounded.

[0012] Furthermore, the A-phase lightning arrester, B-phase lightning arrester, and C-phase lightning arrester are respectively connected to their respective incoming line ends through cables.

[0013] Furthermore, the incoming line ends of the A-phase lightning arrester, B-phase lightning arrester, and C-phase lightning arrester are straight plug-in type plug-and-play connectors, elbow type plug-and-play connectors, rear plug-in type plug-and-play connectors, or front plug-in type plug-and-play connectors.

[0014] The present utility model also provides another three-phase combined shielded plug-and-play lightning arrester, which is characterized in that:

[0015] It includes an A-phase lightning arrester, a B-phase lightning arrester, a C-phase lightning arrester, a grounding lightning arrester D, a shielding housing, and three plugging sleeves;

[0016] The A-phase lightning arrester, B-phase lightning arrester, C-phase lightning arrester, and grounding lightning arrester D are respectively fixedly installed inside the shielding housing. The three plugging sleeves are installed on the shielding housing at intervals. Their outgoing line ends are placed inside the shielding housing and are respectively connected to the incoming line ends of the A-phase lightning arrester, B-phase lightning arrester, and C-phase lightning arrester; the plugging interfaces of the three plugging sleeves are placed outside the shielding housing and are respectively connected to three plug-and-play connection sleeves in an external switchgear through a cable with plug-and-play connectors provided at both ends;

[0017] The outgoing line ends of the A-phase lightning arrester, B-phase lightning arrester, and C-phase lightning arrester are short-circuited to form a neutral point, and the neutral point is connected to the incoming line end of the grounding lightning arrester D;

[0018] The outgoing line end of the grounding lightning arrester D is led out of the shielding housing and then grounded; or, the outgoing line end of the grounding lightning arrester D is connected to the inner wall of the shielding housing, and the outer wall of the shielding housing is grounded.

[0019] Furthermore, the plugging sleeve is an inner cone sleeve or an outer cone sleeve;

[0020] The plug-and-play connector at the end of the cable is of the straight plug-in type, elbow type, rear plug-in type, or front plug-in type.

[0021] The present utility model also provides a third three-phase combined shielded plug-and-play lightning arrester, which is characterized in that:

[0022] It includes a shielding housing, and an AC-phase lightning arrester, an AB-phase lightning arrester, a BC-phase lightning arrester, a BD-phase lightning arrester, an AD-phase lightning arrester, and a CD-phase lightning arrester fixedly installed inside the shielding housing;

[0023] The AC-phase lightning arrester is respectively connected to the A-phase and C-phase plug-and-play sleeves in an external switchgear through a first cable and a third cable with plug-and-play connectors provided at one end;

[0024] The AB-phase lightning arrester is respectively and matingly connected with the A-phase and B-phase plug-in bushings in the external switchgear through a first cable and a second cable each having a plug-in joint at one end;

[0025] The BC-phase lightning arrester is respectively and matingly connected with the B-phase and C-phase plug-in bushings in the external switchgear through a second cable and a third cable each having a plug-in joint at one end;

[0026] The AD-phase lightning arrester is matingly connected with the A-phase plug-in bushing in the external switchgear through a first cable having a plug-in joint at one end, and the other end is led out of the shielding housing and then grounded; or, it is connected to the inner wall of the shielding housing, and the outer wall of the shielding housing is grounded;

[0027] The BD-phase lightning arrester is matingly connected with the B-phase plug-in bushing in the external switchgear through a second cable having a plug-in joint at one end, and the other end is led out of the shielding housing and then grounded; or, it is connected to the inner wall of the shielding housing, and the outer wall of the shielding housing is grounded;

[0028] The CD-phase lightning arrester is matingly connected with the C-phase plug-in bushing in the external switchgear through a third cable having a plug-in joint at one end, and the other end is led out of the shielding housing and then grounded; or, it is connected to the inner wall of the shielding housing, and the outer wall of the shielding housing is grounded.

[0029] Further, it further includes three plug-in bushings installed at intervals on the shielding housing;

[0030] The insertion ports of the three plug-in bushings are located outside the shielding housing, and the outgoing line ends are located inside the shielding housing;

[0031] The other ends of the first cable, the second cable and the third cable are also provided with plug-in joints, and the insertion ports of the three plug-in bushings are respectively and matingly connected with the plug-in joints at the other ends of the first cable, the second cable and the third cable;

[0032] The outgoing line end of the first plug-in bushing among the three plug-in bushings is connected to the AC-phase unit, the AB-phase unit and the AD-phase unit;

[0033] The outgoing line end of the second plug-in bushing among the three plug-in bushings is connected to the AB-phase unit, the BC-phase unit and the BD-phase unit;

[0034] The outgoing line end of the third plug-in bushing among the three plug-in bushings is connected to the AC-phase unit, the BC-phase unit and the CD-phase unit.

[0035] Further, the plug-in bushing is an internal taper bushing or an external taper bushing;

[0036] The plug-in joints at the ends of the first cable, the second cable and the third cable are of the straight plug type, elbow type, rear plug type or front plug type.

[0037] The beneficial effects of the present utility model are as follows:

[0038] 1. In the present utility model, the A-phase lightning arrester, B-phase lightning arrester or C-phase lightning arrester is connected in series with the grounding lightning arrester D to achieve the protection of the relative ground overvoltage of the system. Moreover, when the inter-phase overvoltage occurs in the system, any two of the A-phase lightning arrester, B-phase lightning arrester or C-phase lightning arrester are connected in series to achieve the protection of the inter-phase overvoltage of the system, thereby effectively protecting the inter-phase insulation safety of the power system.

[0039] 2. In the present utility model, three inter-phase lightning arresters - AC-phase lightning arrester, AB-phase lightning arrester and BC-phase lightning arrester are provided. The three inter-phase lightning arresters are connected by the delta connection method to achieve the protection of the inter-phase overvoltage of the system; at the same time, three phase-to-ground lightning arresters - BD-phase lightning arrester, AD-phase lightning arrester and CD-phase lightning arrester are provided. The three phase-to-ground lightning arresters are connected by the star connection method to achieve the protection of the phase-to-ground overvoltage of the system, thereby effectively protecting the inter-phase insulation safety of the power system. Description of the Drawings

[0040] Figure 1 is a schematic structural diagram of the first embodiment of the present utility model;

[0041] Figure 2 is a schematic structural diagram of the second embodiment of the present utility model;

[0042] Figure 3 is a schematic structural diagram of the third embodiment of the present utility model;

[0043] Figure 4 is a schematic structural diagram of the fourth embodiment of the present utility model;

[0044] Figure 5 is a schematic structural diagram of the fifth embodiment of the present utility model.

[0045] In the figure: 1 - shielding housing, 2 - cable, 3 - plug-in bushing, 4 - first cable, 5 - second cable, 6 - third cable. Detailed Embodiments

[0046] To make the objectives, advantages and features of the present utility model clearer, the following further describes in detail a three-phase combined shielded plug-in lightning arrester proposed by the present utility model with reference to the drawings and specific embodiments. According to the following detailed embodiments, the advantages and features of the present utility model will be clearer. It should be noted that: the drawings are all in a very simplified form and use non-precise scales, only for conveniently and clearly assisting in explaining the objectives of the embodiments of the present utility model; secondly, the structures shown in the drawings are often part of the actual structures.

[0047] Embodiment 1

[0048] SeeFigure 1 , a three-phase combined shielded plug-in type lightning arrester in this embodiment mainly includes a phase A lightning arrester, a phase B lightning arrester, a phase C lightning arrester, a shielding housing 1 and a grounding lightning arrester D.

[0049] Among them, the shielding material of the shielding housing 1 can be a metallic conductive material or a non-metallic conductive or semi-conductive material.

[0050] The two ends of the phase A lightning arrester, the phase B lightning arrester and the phase C lightning arrester are respectively provided with an incoming line end and an outgoing line end; the phase A lightning arrester, the phase B lightning arrester and the phase C lightning arrester are installed on the shielding housing 1 at intervals, and their incoming line ends are all plug-in type joints, which are respectively connected in a matching manner with three plug-in connection sleeves in an external switch cabinet, and the outgoing line ends are placed inside the shielding housing 1.

[0051] The grounding lightning arrester D is installed inside the shielding housing 1. The outgoing line ends of the phase A lightning arrester, the phase B lightning arrester and the phase C lightning arrester are short-circuited to form a neutral point, and the neutral point is connected to the incoming line end of the grounding lightning arrester D; the outgoing line end of the grounding lightning arrester D is led out of the shielding housing 1 and then grounded. In other embodiments of the present invention, the outgoing line end of the grounding lightning arrester D can also be connected to the inner wall of the shielding housing 1, and the outer wall of the shielding housing 1 is grounded.

[0052] Specifically, the incoming line ends of the above-mentioned phase A lightning arrester, phase B lightning arrester and phase C lightning arrester are all straight plug-in type joints, the outer shell is a shielded metal housing, and the internal facilities include voltage-limiting elements for restricting overvoltage and insulating jackets for insulating from the shielding housing.

[0053] In other embodiments of the present invention, the incoming line ends of the above-mentioned phase A lightning arrester, phase B lightning arrester and phase C lightning arrester can also be elbow plug-in type joints, rear plug-in type joints or front plug-in type joints, and can be specifically selected according to actual installation requirements.

[0054] When a relative-to-ground overvoltage occurs in the system, the phase A lightning arrester, the phase B lightning arrester or the phase C lightning arrester is connected in series with the grounding lightning arrester D to realize the protection of the relative-to-ground overvoltage of the system. When an inter-phase overvoltage occurs in the system, two inter-phase lightning arresters among the phase A lightning arrester, the phase B lightning arrester and the phase C lightning arrester are connected in series to realize the protection of the inter-phase overvoltage.

[0055] Embodiment Two

[0056] See Figure 2 , the difference between this embodiment and Embodiment One is that the phase A lightning arrester, the phase B lightning arrester and the phase C lightning arrester are respectively connected to their incoming line ends through cables 2. The remaining structure of the present invention is the same as that of Embodiment One.

[0057] Embodiment Three

[0058] See Figure 3, a three-phase combined shielded plug-in type lightning arrester in this embodiment includes an A-phase lightning arrester, a B-phase lightning arrester, a C-phase lightning arrester, a grounding lightning arrester D, a shielding housing 1, and three plug-in bushings 3.

[0059] Specifically, the A-phase lightning arrester, B-phase lightning arrester, C-phase lightning arrester, and grounding lightning arrester D are respectively fixedly installed inside the shielding housing 1. The three plug-in bushings 3 are installed on the shielding housing 1 at intervals, and their outgoing ends are placed inside the shielding housing 1 and are respectively connected to the incoming ends of the A-phase lightning arrester, B-phase lightning arrester, and C-phase lightning arrester. The plug-in interfaces of the three plug-in bushings 3 are placed outside the shielding housing 1 and are respectively connected in a matching manner to three plug-in connection bushings in an external switchgear through cables 2 with plug-in joints provided at both ends. The outgoing ends of the A-phase lightning arrester, B-phase lightning arrester, and C-phase lightning arrester are short-circuited to form a neutral point, and the neutral point is connected to the incoming end of the grounding lightning arrester D. The outgoing end of the grounding lightning arrester D is led out of the shielding housing 1 and then grounded; or, the outgoing end of the grounding lightning arrester D is connected to the inner wall of the shielding housing 1, and the outer wall of the shielding housing 1 is grounded.

[0060] Specifically, the above-mentioned plug-in bushing 3 can be an inner cone bushing or an outer cone bushing, and can be selected according to actual installation needs. The plug-in joints at the ends of the cable 2 are of straight plug type, elbow type, rear plug type, or front plug type, and are also selected according to actual installation needs.

[0061] Embodiment Four

[0062] See Figure 4 , a three-phase combined shielded plug-in type lightning arrester in this embodiment includes a shielding housing 1, and an AC-phase lightning arrester, an AB-phase lightning arrester, a BC-phase lightning arrester, a BD-phase lightning arrester, an AD-phase lightning arrester, and a CD-phase lightning arrester installed inside the shielding housing 1.

[0063] The relative ground overvoltage of the system is limited by the BD-phase lightning arrester, AD-phase lightning arrester, and CD-phase lightning arrester, and the phase-to-phase overvoltage of the system is limited by the AC-phase lightning arrester, AB-phase lightning arrester, and BC-phase lightning arrester. The AC-phase lightning arrester, AB-phase lightning arrester, and BC-phase lightning arrester are connected by a delta connection method, and the BD-phase lightning arrester, AD-phase lightning arrester, and CD-phase lightning arrester are connected by a star connection method.

[0064] Specifically, the A-C phase arrester is respectively and matingly connected to the A-phase and C-phase plug-in bushings in the external switchgear through the first cable 4 and the third cable 6 with plug-in joints provided at one end. The A-B phase arrester is respectively and matingly connected to the A-phase and B-phase plug-in bushings in the external switchgear through the first cable 4 and the second cable 5 with plug-in joints provided at one end. The B-C phase arrester is respectively and matingly connected to the B-phase and C-phase plug-in bushings in the external switchgear through the second cable 5 and the third cable 6 with plug-in joints provided at one end. The A-D phase arrester is respectively and matingly connected to the A-phase plug-in bushing in the external switchgear through the first cable 4 with a plug-in joint provided at one end. The other end is led out of the shielding housing 1 and then grounded; or, it is connected to the inner wall of the shielding housing 1, and the outer wall of the shielding housing 1 is grounded. The B-D phase arrester is respectively and matingly connected to the B-phase plug-in bushing in the external switchgear through the second cable 5 with a plug-in joint provided at one end. The other end is led out of the shielding housing 1 and then grounded; or, it is connected to the inner wall of the shielding housing 1, and the outer wall of the shielding housing 1 is grounded. The C-D phase arrester is respectively and matingly connected to the C-phase plug-in bushing in the external switchgear through the third cable 6 with a plug-in joint provided at one end. The other end is led out of the shielding housing 1 and then grounded; or, it is connected to the inner wall of the shielding housing 1, and the outer wall of the shielding housing 1 is grounded.

[0065] Embodiment 5

[0066] See Figure 5 , the difference between this embodiment and Embodiment 4 is that three plug-in bushings 3 are installed on the shielding housing 1 in this embodiment; the insertion ports of the three plug-in bushings 3 are placed outside the shielding housing, and the outgoing ends are placed inside the shielding housing 1; plug-in joints are also provided at the other ends of the first cable 4, the second cable 5, and the third cable 6, and the insertion ports of the three plug-in bushings 3 are respectively and matingly connected to the plug-in joints at the other ends of the first cable 4, the second cable 5, and the third cable 6; among them, the outgoing end of the first plug-in bushing is connected to the A-C phase arrester, the A-B phase arrester, and the A-D phase arrester; the outgoing end of the second plug-in bushing is connected to the A-B phase arrester, the B-C phase arrester, and the B-D phase arrester; the outgoing end of the third plug-in bushing is connected to the A-C phase arrester, the B-C phase arrester, and the C-D phase arrester. The rest of the structure of this embodiment is the same as that of Embodiment 4.

Claims

1. A three-phase combined shielded pluggable arrester, characterized in that: It comprises an A-phase lightning arrester, a B-phase lightning arrester, a C-phase lightning arrester, a shielding shell (1) and a grounding lightning arrester D; The two ends of the A-phase lightning arrester, the B-phase lightning arrester and the C-phase lightning arrester are respectively provided with an inlet terminal and an outlet terminal; The A-phase lightning arrester, the B-phase lightning arrester and the C-phase lightning arrester are installed at intervals on the shielding shell (1); their inlet ends are all plug-in connectors, which are matched and connected to three plug-in connection sleeves in the external switch cabinet respectively; and their outlet ends are placed inside the shielding shell (1) and are electrically insulated from the shielding shell (1); The grounding arrester D is installed in the shielding shell (1), the outgoing terminals of the A-phase arrester, the B-phase arrester and the C-phase arrester are short-circuited to form a neutral point, and the neutral point is connected to the incoming terminal of the grounding arrester D; The outlet terminal of the grounded lightning arrester D is led out of the shielding shell (1) and then grounded; or, the outlet terminal of the grounded lightning arrester D is connected to the inner wall of the shielding shell (1), and the outer wall of the shielding shell (1) is grounded.

2. The three-phase combined shielded pluggable arrester according to claim 1 is characterized in that: The A-phase lightning arrester, the B-phase lightning arrester and the C-phase lightning arrester are respectively connected to their respective incoming line terminals via cables (2).

3. The three-phase combined shielded pluggable arrester according to claim 1 or 2, characterized in that: The incoming line ends of the A-phase lightning arrester, the B-phase lightning arrester and the C-phase lightning arrester are straight-insertion plug-in connectors, elbow-type plug-in connectors, rear-insertion plug-in connectors or front-insertion plug-in connectors.

4. A three-phase combined shielded pluggable arrester, characterized in that: It comprises an A-phase lightning arrester, a B-phase lightning arrester, a C-phase lightning arrester, a grounding lightning arrester D, a shielding shell (1) and three plug-in sleeves (3); The A-phase lightning arrester, the B-phase lightning arrester, the C-phase lightning arrester and the grounding lightning arrester D are respectively fixedly installed in the shielding shell (1); three plug-in sleeves (3) are installed on the shielding shell (1) at intervals; their outlet ends are placed in the shielding shell (1) and are respectively connected to the inlet ends of the A-phase lightning arrester, the B-phase lightning arrester and the C-phase lightning arrester; the plug-in interfaces of the three plug-in sleeves (3) are placed outside the shielding shell (1) and are respectively matched and connected to three plug-in connection sleeves in the external switch cabinet through a cable (2) with plug-in connectors at both ends; The outgoing terminals of the A-phase lightning arrester, the B-phase lightning arrester and the C-phase lightning arrester are short-circuited to form a neutral point, and the neutral point is connected to the incoming terminal of the grounding lightning arrester D; The outlet terminal of the grounded lightning arrester D is led out of the shielding shell (1) and then grounded; or, the outlet terminal of the grounded lightning arrester D is connected to the inner wall of the shielding shell (1), and the outer wall of the shielding shell (1) is grounded.

5. The three-phase combined shielded pluggable arrester according to claim 4 is characterized in that: The plug-in sleeve (3) is an inner cone sleeve or an outer cone sleeve; The plug-in connector at the end of the cable (2) is a straight-insertion type, an elbow type, a rear-insertion type or a front-insertion type.

6. A three-phase combined shielded pluggable arrester, characterized in that: It comprises a shielding shell (1), and an AC phase lightning arrester, an AB phase lightning arrester, a BC phase lightning arrester, a BD phase lightning arrester, an AD phase lightning arrester, and a CD phase lightning arrester fixedly installed in the shielding shell (1); The AC phase lightning arrester is respectively connected to the A-phase and C-phase plug-in bushings in the external switch cabinet through a first cable (4) and a third cable (6) provided with a plug-in connector at one end; The AB phase lightning arrester is respectively connected to the A phase and B phase plug-in bushings in the external switch cabinet through a first cable (4) and a second cable (5) with a plug-in connector at one end; The BC phase lightning arrester is respectively connected to the B phase and C phase plug-in bushings in the external switch cabinet through a second cable (5) and a third cable (6) provided with a plug-in connector at one end; The AD phase lightning arrester is matched and connected to the A phase plug-in bushing in the external switch cabinet via a first cable (4) having a plug-in connector at one end, and the other end is led out of the shielding shell (1) and then grounded; or, connected to the inner wall of the shielding shell (1), and the outer wall of the shielding shell (1) is grounded; The BD phase lightning arrester is matched and connected to the B phase plug-in bushing in the external switch cabinet via a second cable (5) having a plug-in connector at one end, and the other end is led out of the shielding shell (1) and then grounded; or, connected to the inner wall of the shielding shell (1), and the outer wall of the shielding shell (1) is grounded; The CD phase lightning arrester is matched and connected to the C phase plug-in bushing in the external switch cabinet via a third cable (6) having a plug-in connector at one end, and the other end is led out of the shielding shell (1) and then grounded; or, it is connected to the inner wall of the shielding shell (1), and the outer wall of the shielding shell (1) is grounded.

7. The three-phase combined shielded pluggable arrester according to claim 6 is characterized in that: It also includes three plug-in sleeves (3) installed at intervals on the shielding shell (1); The plug-in interfaces of the three plug-in sleeves (3) are arranged outside the shielding shell (1), and the outlet terminals are arranged inside the shielding shell (1); The other ends of the first cable (4), the second cable (5) and the third cable (6) are also provided with plug-in connectors, and the plug-in interfaces of the three plug-in sleeves (3) are respectively matched and connected with the plug-in connectors at the other ends of the first cable (4), the second cable (5) and the third cable (6); The outlet end of the first plug-in sleeve of the three plug-in sleeves (3) is connected to the AC phase unit, the AB phase unit and the AD phase unit; The outlet end of the second plug-in sleeve of the three plug-in sleeves (3) is connected to the AB phase unit, the BC phase unit and the BD phase unit; The outlet end of the third plug-in sleeve of the three plug-in sleeves (3) is connected to the AC phase unit, the BC phase unit and the CD phase unit.

8. The three-phase combined shielded pluggable arrester according to claim 7 is characterized in that: The plug-in sleeve (3) is an inner cone sleeve or an outer cone sleeve; The plug-in connectors at the ends of the first cable (4), the second cable (5) and the third cable (6) are straight-insertion type, elbow-insertion type, rear-insertion type or front-insertion type.

Images