JPH11341628A - Insulated bus system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable insulated bus system which has a simple constitution, does not require many parts, can be field-assembled easily with high workability. SOLUTION: In an insulated bus system composed of an insulated bus 30 which connects two T-shaped bushings to each other and an insulating pipe provided between the bus 30 and bushings, each bushing is provided with an insulating bushing having a leg section and a pair of arm sections and a T-shaped conductor arranged in the insulating bushing and the insulated bus 30 is provided with a flat square conductor 31, an insulating layer 32 arranged on the outside of the conductor 31, and internal shielding layers formed on the internal and external surfaces of the layer 32. The insulating pipe is provided with an insulating reinforcing layer which connects the arm sections of the insulating bushing to the external surface of the insulated bus 3 between the bus 30 and insulating layer 32 and an external shielding layer 33 formed on the outer periphery of the pipe and the connecting conductor of the T-shaped conductor and the flat square conductor 31 of the bus 30 are fastened to each other with a fastening bolt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulated bus system for electrically connecting adjacent electric devices using an insulated bus.

[0002]

2. Description of the Related Art As electrical equipment such as a switchboard, a transformer, or a gas insulated switch (GIS) disposed in various plants and buildings, those having a cubicle type board configuration are frequently used. Usually, these boards of the same shape and the same size are arranged in a required number and adjacent to each other, and the boards are electrically connected by an insulating bus.

FIG. 12 shows an example of a conventional inter-panel connection method. A T-shaped insulated busbar 3 is attached to an upper surface or a side surface of a panel 1 via an insulating bushing 2, respectively. Each of these insulated buses 3 is formed by assembling a rod-shaped or pipe-shaped conductor into a T-shape to form a center conductor 4 and coating the periphery thereof with an epoxy resin or the like to form an insulating layer 5. The outer shielding layer 6 is formed by applying metallikon or the like. Each panel is shipped from the factory with the insulated busbars 3 attached to it, transported to the installation site, fixed in position, and then insulated with the insulated busbars 3 of the adjacent board.
And the power supply side or the load side are sequentially connected for each phase.

When connecting these insulated busbars 3, a small diameter portion is formed at the end of the exposed central conductor 4, and a large number of finger contacts 7 and a plurality of coil springs 8 are formed between them. A current path is formed by mounting the tulip contact 9 and the outside thereof is straddled between the insulating layers 5 on both sides and covered with an insulating cylinder 10 to provide reinforcement insulation. Prior to the installation of the panel 1, the tulip contact 9 and the insulating tube 10 are inserted on the center conductor 4 of one of the insulating busbars 3 or on the external shielding layer 6, and after the installation of the panel 1, Pulled back for electrical or insulated connection.

[0005]

In the inter-panel connection method having the above-described structure, since the connection of the center conductor 4 of the insulating bus 3 is performed by the tulip contact 9, the allowable range of the positional deviation of the adjacent panels 1 is provided. Is very small, and the positioning work at the time of installing the board 1 is not easy. Further, the tulip contact 9 and the insulating tube 10 are pulled back to a predetermined position by using a man or a tool after the installation of the board 1. However, if there is a step between the center conductors 4 of the insulating bus 3, these pull-back operations are performed. Becomes very difficult, the workability is poor, and the electrical performance of the obtained connection may be adversely affected, and there is also a problem in reliability. If the insulating busbar 3 or the tulip contact 9 is damaged for any reason, when replacing them, the insulating busbar 3 must be removed together with the insulating bushing 2, which is a large-scale operation, and in particular, the board 1 is a GIS. In the case of a device filled with an insulating fluid as described above, operations such as recovery and refilling of the insulating fluid are also required, so that a more extensive operation is inevitable. In addition, since both ends of the center conductor 4 of the insulating busbar 3 project beyond the casing of the panel 1, the panel 1 may be damaged by contact with other objects during transportation or installation of the panel 1. Careful transportation and installation require careful attention, and this may also reduce workability.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above problems and to provide an insulated bus system having a simple structure, a small number of necessary parts, easy on-site assembly work, and high workability and reliability. It is.

[0007]

SUMMARY OF THE INVENTION An insulated bus system according to the present invention includes a T-shaped bushing attached to a casing of an electric device, an insulated busbar connecting two T-shaped bushings,
In the insulating bus system including the insulating bus and an insulating cylinder provided between the T-shaped bushing, the T-shaped bushing includes a leg penetrating a casing of the electric device and a pair of arms extending in a direction perpendicular to the leg. And an insulating bushing provided with the connecting bushing and a connecting portion at a tip end of the connecting conductor protruding from an arm of the insulating bushing.
Type conductor, the insulating bus bar, a rectangular conductor,
An insulating layer disposed outside the connecting portions at both ends thereof, and an inner shielding layer and an outer shielding layer provided on the inner and outer surfaces of the insulating layer, wherein the insulating cylinder includes an insulating bushing arm and an insulating busbar. An insulating reinforcing layer electrically connecting the outer surface between the insulating layer and the insulating layer, and an outer shielding layer formed on the outer periphery thereof, the connecting conductor of the T-type conductor and the rectangular conductor of the insulating bus, Are overlapped and fastened by bolts penetrating them.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a T-shaped conductor is arranged in a pair of arm portions of an insulating bushing except for a connecting portion at a tip end and a flat plate-shaped lead conductor penetrating through a leg portion of the insulating bushing. It can be composed of a pair of flat connection conductors connected to the conductor via bolts.
The connection conductor may be provided with a loosely curved slack portion. The insulating bus can have a spacer interposed between the rectangular conductor and the inner shielding layer outside the rectangular conductor at appropriate intervals in the length direction of the insulating bus. It is desirable to insert a connecting spacer around the outer periphery of a fastening bolt for fastening between the connecting conductor of the T-shaped conductor and the rectangular conductor of the insulating bus. It is preferable that an inner shielding layer is provided on the inner surface of the insulating reinforcing layer of the insulating cylinder so as to extend between the connecting spacer, the tip of the arm of the insulating bushing, and the tip of the insulating layer of the insulating bus. Between the outer shielding layer of the insulating busbar and the outer shielding layer of the insulating tube, an insulating reinforcing layer of the insulating tube may be interposed to form an electric margin. Further, it is desirable to provide a protective cover made of a metal material outside the insulating cylinder, and to ground this protective cover together with the external shielding layer of the insulating bus via a ground wire.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows the overall configuration of an insulated bus system according to the present invention. A T-shaped bushing 20 for each phase is diagonally little by little on the upper surface or side surface of each of the arranged disks 1. The three T-type bushings 20 of the adjacent boards 1 are connected by an insulating bus bar 30 for each phase. Further, the T-shaped bushing 20 and the insulating bus 30 are connected by an insulating cylinder 40, respectively. Although not shown in FIG. 1, a protective cover 50 (see FIG. 7) is attached to the outer periphery of the insulating cylinder 40, and is grounded together with the external shielding layer of the insulating bus 30 via a ground line.

As shown in FIGS. 2 to 4, the T-shaped bushing 20 includes an insulating bushing 21 made of epoxy resin,
And a T-shaped conductor 22 disposed in the insulating bushing. The insulating bushing 21 is provided on the casing 1a of the board.
And a pair of cylindrical arms 21b and 21c extending in a direction perpendicular to the legs 21a. The T-shaped conductor 22 is a pair of flat-plate-like lead conductors 23 embedded and molded in the leg portions 21a and a pair of the lead conductors 23 attached near the upper end (the upper end in FIG. 4) of the lead conductor 23 in the arm portions 21b and 21c of the insulating bushing 21. Connection conductor 2
4 and 25. The connecting conductors 24 and 25 are respectively bent at right angles in the vicinity of the inner end of the flat conductor,
The extraction conductor 23 and the side surfaces (large surfaces) are overlapped so as to be in parallel contact with each other, and attached by tightening a nut 27 to a bolt 26 penetrating therethrough. The bent portions of the connecting conductors 24 and 25 are gently curved, and the slack portions 24 are formed.
a, 25a. These slack portions exhibit a function of absorbing thermal expansion and contraction of the insulating busbar 30 and adjusting a slight displacement between the T-shaped bushing 20 and the insulating busbar 30. As shown in FIG. 2, the connecting portions at the ends (there are holes for inserting fastening bolts) in the connecting conductors 24 and 25 are formed on the arm portions 21 of the insulating bushing 21.
b, 21c. At the lower end of the lead conductor 23 projecting from the leg portion 21a of the insulating bushing 21, a connecting portion 26 for connecting a wiring in the board is fixed.

As shown in FIG. 5, the insulating bus 30 includes a rectangular conductor 31 made of a copper band or the like, and a cylindrical insulating layer 32 covering the rectangular conductor. Holes for inserting fastening bolts are formed at both ends of the rectangular conductor 31 to form a connecting portion. The insulating layer 32 is made of EP rubber or the like, and an inner shielding layer 33 and an outer shielding layer 34 are formed on the inner and outer surfaces of the insulating layer 32 in close contact with each other. The internal shielding layer 33 can be formed by kneading a mixture of EP rubber and conductive particles such as carbon black together with the insulating layer 32. The outer shielding layer 34 is made of the same material as that of the inner shielding layer 32.
2, an external semiconductive layer is formed by molding, and a thin metal plate such as a copper foil is wound around and fixed to a cylindrical shape in close contact with the outside.

The insulating layer 32 and the inner shielding layer 33 are slightly shorter than the rectangular conductor 31 as shown in FIG. 3 and the like, so that the connecting portions at both ends of the rectangular conductor 31 project from the insulating layer 32 and the like. ing. The inner shielding layer 33 is provided on the inner surface of the insulating layer 32 over the entire length thereof, but the outer shielding layer 34 is shorter than the entire length of the insulating layer 32, and thus the surfaces near both ends of the insulating layer 32 are exposed. . Although not shown, the outer shielding layer 34 is provided with a terminal seat for connecting a ground wire at an intermediate portion thereof, and a portion other than the terminal seat is covered with a protective tube or the like to form a protective layer. It is desirable.

Between the insulating layer 32 and the inner shielding layer 33,
Spacers 35 are interposed at appropriate intervals in the length direction of the insulating bus bar 30. This spacer is a rectangular conductor 31
And a certain degree of free behavior of the insulating layer 32 to absorb the difference in thermal expansion and contraction thereof. The insulating layer 32 is made of a flexible material such as EP rubber and has a large number of through holes 35a along its axial direction.
Are formed.

As shown in FIG. 6, the insulating cylinder 40 includes an insulating reinforcing layer 41 and an inner shielding layer 42 formed at the center of the inner surface thereof.
And an outer shielding layer 43 formed over the entire outer circumference of the insulating reinforcing layer 41. The insulating reinforcing layer 41 is made of a relatively flexible elastic insulating material such as EP rubber,
2 and the outer shielding layer 43 are made of a material obtained by kneading conductive particles such as carbon black into the same material, and the insulating cylinder 40 can be manufactured by molding these materials in three layers at a time. The insulating cylinder 40 has ring-shaped recesses 40a, 40 for attaching a band near both ends in the longitudinal direction.
b is formed.

FIGS. 7 and 8 show a protective cover 50 which is provided on the insulating cylinder 40 for protection and grounding. The protective cover 50 is made of a conductive metal material such as aluminum and is divided into an upper cover 51 and a lower cover 52 which are vertically divided into two along the length direction. The upper cover 51 and the lower cover 52 are used in combination in a cylindrical shape.
0 and the shape and dimensions are in contact with the outer surface. However, the outer ends (left ends in FIG. 7) 51a and 52a in the length direction of the upper cover 51 and the lower cover 52 are slightly longer than the outer end 40c of the insulating tube 40. The inner end (right end in FIG. 7) portion 51b in the length direction is slightly longer than the inner end portion 40d of the insulating cylinder 40, and a semicircular projection 51e projecting to the inner surface is formed at the end. .

When assembling the insulated bus bar system of the present invention using the above-mentioned main components, a plurality of boards 1 having a T-shaped bushing 20 previously mounted at the same axial position on the upper surface or side surface are arranged in a predetermined position. After the boards are mounted, an insulating bus bar 30 is attached between the T-shaped bushings 20 of the same phase on the adjacent boards 1. In this attachment, as shown in FIG. 9, insulating cylinders 40 are previously inserted into the insulating bus 30 from both sides thereof, and the connecting portions 31a at both ends of the rectangular conductor 31 of the insulating bus 30 are connected to the insulating cylinder 4.
0 protrudes from the inner end 40d. As shown in FIGS. 3 and 4, these connecting portions 31 a are connected to T-shaped conductors 2 protruding from the arms 21 b and 21 c of the insulating bushing 21.
The connecting portions of the two connecting conductors 24 and 25 are overlapped so that the side surfaces (large surfaces) are in parallel contact with each other, and the fastening bolt 36 is inserted into the fastening bolt insertion hole penetrating them, and the nut 37 is tightened.

When the connection between the rectangular conductor 31 and the T-shaped conductor 22 of the insulated bus is thus completed, the connecting spacer 38 is assembled so as to cover the bolted portion. The connection spacer 38 is formed by molding a material obtained by kneading EP rubber with carbur black or the like and imparting conductivity to a cylindrical shape, and connecting the connection portions between the rectangular conductor 31 and the connection conductors 24 and 25 and the fastening bolt 36 to the inner surface thereof. A hollow portion capable of accommodating the nut 37 is formed, and a crack for mounting is formed from the hollow portion to the outer peripheral surface. The crack is opened and mounted on the bolted portion. By mounting the connecting spacer 38, the insulating layer 32 of the insulating busbar 30 and the arm 21 of the insulating bushing 21 are formed.
b and 21c are connected.

Next, the insulating cylinder 40 previously inserted into the insulating bus bar 30 is slid and moved so that the inner ends thereof are in close contact with the bases of the arms 21b and 21c of the insulating bushing 21. In this state, the inner shielding layer 42 of the insulating cylinder 40 is located outside the connecting spacer 38 and is in close contact with each other due to their rubber-like elasticity to conduct semiconductively. Due to the rubber-like elasticity of the insulating reinforcing layer 41, the insulating busbar 30 and the insulating layer 32 exposed on the outer surface near both ends and between the insulating reinforcing layer 41 and the arms 21b and 21c of the insulating bushing 21 are in close contact with each other. Maintain dielectric strength. The outer shielding layer 4 of the insulating cylinder 40
An insulating reinforcing layer 41 is interposed between the insulating bush 3 and the outer shielding layer 34 of the insulating bus 30 to form an electric margin.

After the pulling back and positioning of the insulating cylinder 40 are completed, the protective cover 50 is attached to the insulating cylinder 40. This is achieved by arranging an upper cover 51 and a lower cover 52 in a cylindrical combination on the outside of the insulating tube 40, and forming ring-shaped concave portions 51c, 52c and 51d, 52d for attaching the bands as shown in FIG. Then, fixing bands 53 and 54 are attached and tightened. In this case, the upper cover 51 is positioned so that a semi-circular projection 51 e formed by projecting from the inner surface of the inner end portion is fitted into the edge portion of the groove 21 d provided at the center of the insulating bushing 21. 52 is positioned in accordance with the upper cover 51. As the fixed bands 53 and 54, conductive metal bands are used, and a ground wire is connected using these bands. That is, as shown in FIG.
An insulated bus ground wire 61 is connected between a terminal seat 34a provided at an intermediate portion of the outer shielding layer 34 of the insulated bus bar 30 and a fixed band 53 of one of the protective covers 50, and faces each other with the insulating bushing 21 interposed therebetween. A ground wire 62 across the protective cover is connected between the fixed bands 54, and a lead ground wire 63 is attached to one of the fixed bands 54, and the other end is grounded. The attachment of these ground wires is performed separately for each panel 1. In this case, the grounding of the outer shielding layer 34 of the insulated busbar 30 is performed through the fixing band 53 of the protective cover 50 attached to one of the panels to form an electric margin.

As described above, the adjacent boards 1 are connected to each other by the insulated buses 30 for each phase, and a terminal spacer 70 as shown in FIG. A stopper 80 is attached. The terminal spacer 70 is manufactured using the same material as that of the connection spacer 38 described above, but has an inner surface formed with a hollow portion enough to accommodate only the connection portion of the single connection conductor 25, and No cracks are formed. The insulating plug 80 includes an insulating reinforcing layer 81, an inner shielding layer 82 formed on the inner surface thereof, and an outer shielding layer 83 formed on the outer periphery of the insulating reinforcing layer 81. One end of each layer surrounds the terminal spacer 70. Is closed in this way. The insulating reinforcing layer 81 is made of a relatively flexible elastic insulating material such as EP rubber, and the inner shielding layer 82 and the outer shielding layer 83 are made of a material obtained by kneading conductive particles such as carbon black in the same material. It is manufactured by molding three layers of material. On the outer periphery of the insulating plug 80, ring-shaped concave portions 80a and 80b for band attachment are formed near both ends in the length direction. Insulation plug 80
Is covered on one arm 21c of the insulating bushing 21 by utilizing the rubber-like elasticity to maintain the dielectric strength at the line terminal. A metal protective cover 90 having a similar inner surface shape is covered on the outside of the insulating plug 80 as shown in FIG. 10 and is fixed by fixing bands 53 and 54 and grounded by a ground wire 63. You.

As described above, in the insulated busbar system of the present invention, the T-shaped bushings attached to the casing of a panel or other electric equipment in advance are connected by the insulated busbars. The connection between the conductor and the rectangular conductors of the insulated bus is made by tightening nuts to the fastening bolts inserted in their connection parts, and insulated with the T-shaped bushing without attaching the insulating cylinder and the connection spacer yet. Since the connection is made in the open space between the busbars, the connection can be made with extremely simple work without using special tools. Even a slight displacement of the casing of the electric device can be absorbed by deformation of the connecting conductor of the T-shaped conductor and the rectangular conductor of the insulating bus, so that the setting operation of the electric device is also facilitated. In addition, even if it becomes necessary to remove the insulating bus or the insulating cylinder due to some circumstances, it is possible to cope with the simple operation without moving the electric equipment or removing the T-shaped bushing, thereby improving workability.

In the insulated bus system according to the present invention, the insulated bus bar has a rectangular conductor supported in the insulating layer via a spacer arranged at intervals, but a flexible material and shape are used as the spacer. Accordingly, the restraint between the rectangular conductor and the insulating layer can be moderated, and it is possible to sufficiently cope with thermal expansion and contraction and shaft runout. In particular, when a loosely curved portion is provided in the connection conductor of the T-shaped bushing, the function is further improved.

A gap between the insulating layer of the insulating bus and the arm of the insulating bushing is formed by inserting a connecting spacer around the outer periphery of the fastening bolt for fastening the connecting conductor of the T-shaped conductor and the rectangular conductor of the insulating bus. And the connection spacer is made of a semiconductive material, so that the unevenness of the bolted portion can be electrically shielded. By providing an internal shielding layer on the inner surface of the insulating reinforcing layer of the insulating cylinder, between the connecting spacer, the tip of the arm of the insulating bushing, and the tip of the insulating layer of the insulating bus, the electricity applied to the insulating reinforcing layer of the insulating cylinder is provided. Mitigation of mental stress. Between the outer shielding layer of the insulating busbar and the outer shielding layer of the insulating cylinder, if an insulating reinforcing layer of the insulating cylinder is interposed, and an electrical margin is formed,
Inspection of the ground circuit becomes easy. In addition, by providing a protective cover made of a metal material outside the insulating cylinder and grounding this protective cover together with the outer shielding layer of the insulating bus via a ground wire, even in the event of a ground fault, A ground fault current can flow, and safety can be further improved.

[0025]

As described above, according to the present invention, it is possible to provide an insulated bus system which has a simple structure, requires a small number of parts, can be easily assembled on site, and has high workability and reliability.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of the entire insulated bus system of the present invention (provided that a protective cover and a ground wire have not been attached yet).

FIG. 2 is a plan view illustrating a T-shaped bushing used in the present invention.

FIG. 3 is a vertical cross-sectional view showing a state in which an insulating bus bar and an insulating cylinder are attached to a T-shaped bushing according to the present invention.

FIG. 4 is a longitudinal sectional side view of the state of FIG. 3;

FIG. 5 is a cross-sectional view illustrating an insulating bus used in the present invention.

FIG. 6 is a longitudinal sectional view illustrating an insulating cylinder used in the present invention.

FIG. 7 is a longitudinal sectional view illustrating a protective cover used in the present invention.

FIG. 8 is a front view of the protective cover shown in FIG. 7;

FIG. 9 is a plan view showing a state where an insulating tube is mounted on an insulating bus used in the present invention.

FIG. 10 is a plan view illustrating one phase of the insulated bus system of the present invention.

FIG. 11 is a longitudinal sectional plan view showing a configuration example of a terminal portion of the insulated bus system of the present invention.

FIG. 12 is a partial longitudinal sectional view showing an example of a conventional inter-board connection method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Board 2, 21 ... Insulating bushing 3, 30 ... Insulating busbar 4 ... Center conductor 5, 32 ... Insulating layer 6, 34, 43, 83 ... Outer shielding layer 9 ... Tulip contact 10, 40 ... insulating cylinders 33, 42, 82 ... inner shielding layer 20 ... T-shaped bushing 21a ... legs 21b, 21c ... arms 22 ... T-shaped conductor 23 ... lead-out conductor 24, 25 ... connecting conductor 30 ... ... Insulated bus bar 31 ... Square conductor 34a ... Terminal seat 35 ... Spacer 38 ... Connecting spacer 41,81 ... Insulation reinforcing layer 50 ... Protective cover 51 ... Top cover 52 ... Bottom cover 53,54 ... Fixed band 61 Insulated busbar ground wire 62 Protective cover crossing ground wire 63 Draw-out ground wire 70 Terminal spacer 80 Protective cover 90 Protective cover

Claims (8)

[Claims] 1. A T-type bushing attached to a casing of an electric device, an insulating bus connecting two T-type bushes, and an insulating cylinder provided between the insulating bus and the T-type bushing. In an insulated bus system, the T
The mold bushing includes an insulating bushing having a leg penetrating through the casing of the electric device and a pair of arms extending in a direction orthogonal to the casing, and a connecting portion disposed at the insulating bushing and having a leading end of a connecting conductor. A T-shaped conductor protruding from an arm portion of the insulating bushing, wherein the insulating bus bar is provided on the inner and outer surfaces of the rectangular conductor, an insulating layer disposed outside the connecting portions at both ends thereof, and the insulating layer. An inner shielding layer and an outer shielding layer, wherein the insulating cylinder electrically insulates an outer surface between the arm portion of the insulating bushing and the insulating layer of the insulating busbar; And a connecting conductor of the T-shaped conductor and a rectangular conductor of the insulating bus are overlapped at their connecting portions and fastened by fastening bolts penetrating them. You Insulated bus system. 2. The T-shaped bushing is disposed in a pair of plate-shaped lead conductors penetrating the legs of the insulating bushing and a pair of arms of the insulating bushing except for a connecting portion at the tip, and is connected to the lead conductors with bolts. The insulated bus system according to claim 1, comprising a pair of flat-plate-like connecting conductors connected by connection. 3. The insulated busbar system according to claim 2, wherein the connecting conductor is provided with a loosely curved slack portion. 4. The insulating bus bar has spacers interposed between the rectangular conductor and the inner shielding layer outside the rectangular bus bar at appropriate intervals in the length direction of the insulating bus bar. 4. The insulated busbar system according to any one of claims 1 to 3. 5. The connecting spacer according to claim 1, wherein a connecting spacer is inserted around an outer periphery of a fastening bolt for fastening the connecting conductor of the T-shaped conductor and the rectangular conductor of the insulating bus. 2. The insulated busbar system according to claim 1. 6. An inner shielding layer is provided on the inner surface of the insulating reinforcing layer of the insulating cylinder so as to extend between the connecting spacer, the tip of the arm of the insulating bushing, and the tip of the insulating layer of the insulating bus. The insulated bus system according to any one of claims 1 to 5, characterized in that: 7. An insulating reinforcing layer of the insulating cylinder is interposed between the outer shielding layer of the insulating bus and the outer shielding layer of the insulating cylinder to form an electric margin. Claim 1
An insulated busbar system according to any one of claims 1 to 6. 8. A protective cover made of a metal material is provided outside the insulating cylinder, and the protective cover is grounded via a ground wire together with an outer shielding layer of the insulating bus. An insulated busbar system according to any one of the preceding claims.