AU2019210092B2

AU2019210092B2 - Surface leakage robust section insulator

Info

Publication number: AU2019210092B2
Application number: AU2019210092A
Authority: AU
Inventors: Urs Wili
Original assignee: Furrer and Frey AG
Current assignee: Furrer and Frey AG
Priority date: 2018-01-16
Filing date: 2019-01-15
Publication date: 2023-03-16
Anticipated expiration: 2039-01-15
Also published as: KR102624843B1; CN111527007A; CN111527007B; WO2019142098A1; CN210617902U; EP3740397A1; KR20200106040A; DE102018100893A1; TWI816737B; AU2019210092A1; TW201940362A

Abstract

The invention relates to a Section insulator (19) for separating a first current rail section (20) from a second current rail section (21) that extend in a driving direction (1) of a train comprising: - an insulation body (26) extending in the driving direction (1), in a cross direction (11) perpendicular to the driving direction (1) and in a height direction (9) perpendicular to the cross direction (11) and the driving direction (1), - a first connection interface (40, 41) located seen in the driving direction (1) at the beginning (38) of the insulation body (26) for connecting the insulation body (26) to the first current rail (20), - a second connection interface (41) located seen in the driving direction (1) at the end (39) of the insulation body (26) for connecting the insulation body (26) to the second current rail (21), - a contact surface (48) that is seen in the height direction (9) located at the bottom side (42) of the insulation body (26) for supporting a pantograph (30) of the train, - a first insulation body side wall (51) that defines a border of the insulation body (26) at one side in the cross direction (11), - a second insulation body side wall (52) that defines the border of the insulation body (26) seen in the cross direction (11) opposite to the first insulation body side wall (51), - a number of grooves (50) of more then ten that are formed at the contact surface (48) into the insulation body (26) having a groove course (23) running from the first insulation body side wall (51) to the second insulation body side wall (52), wherein the groove course (23) has an inclination angle (54) to the driving direction (1) that is higher than 140° but lower than 180° at at least on one of the first insulation body side wall (51) and the second insulation body side wall (52), and wherein the groove walls (55) in the grooves (50) that are aligned to the front side (38) of the insulation body (26) seen in driving direction (11) include a scraping edge (57) at the contact surface (48).

Description

surface leakage robust section insulator

Description

The present invention relates to a section insulator for separating a first current rail section from a second current rail section that extends in a driving direction of a train.

Such a section insulator is known from EP 0 052 176 Bl.

It is object of the invention to improve the known section insulator.

The object is solved by the features of the independent claims.

Advantageous embodiments are subject of the dependent claims.

According to an aspect of the invention, a section insulator for separating a first current rail section from a second current rail section that extends in a driving direction of a train comprises an insulation body extending in the driving direction, in a cross direction perpendicular to the driving direction and in a height direction perpendicular to the cross direction and the driving direction, a first connection interface located seen in the driving direction at the beginning of the insulation body for connecting the insulation body to the first current rail, a second connection interface located seen in the driving direction at the end of the insulation body for connecting the insulation body to the second current rail, a contact surface that is seen in the height direction located at the bottom side of the insulation body for supporting a pantograph of the train, a first insulation body side wall that defines a border of the insulation body at one side in the cross direction, a second insulation body side wall that defines the border of the insulation body seen in the cross direction opposite to the first insulation body side wall and a number of grooves of more then ten that are formed at the contact surface into the insulation body having a groove course running from the first insulation body side wall to the second insulation body side wall, wherein the groove course has an inclination angle to the driving direction that is higher than 140° but lower than 180° at at least on one of the first insulation body side wall and the second insulation body side wall, and wherein the groove walls in the grooves that are aligned to the front side of the insulation body seen in driving direction include a scraping edge at the contact surface.

The provided section insulator is based on the thought that surface leakage occurs due to deposits of abrasions, like coal dust that

electrically shortens the two current rail sections. With the scarping edge at the groove, the provided section insulator grinds the coal dust into the groove, while the groove transports the ground abrasion out of it by the comparably low inclination angle. This takes away the coal dust from the bottom side of the insulation body and prevents the surface leakage.

In an embodiment of the provided section insulator, the inclination angle at the at least on one of the first insulation body side wall and the second insulation body is higher than 155° but lower than 165°, preferably higher than 150° but lower than 160° and most preferably 155°. With this value for the inclination angle, the grooves will reliably take away the ground abrasion. On the other hand, the grooves will not get not to long preventing that the ground abrasion cannot leave the groove.

In another embodiment of the provided section insulator, a mean value of the inclination angle of the groove course between the first insulation body side wall to the second insulation body side wall is is higher than 140° but lower than 180°, preferably higher than 150° but lower than 177,5° and most preferably 155°. The groove course may thus not be linear, but can also be partially circular, tapered or the like. In a further embodiment of the provided section insulator, a ratio between an area of the contact surface covered by the grooves and a remaining area of the contact surface is between 1:2 and 1:4, preferably 1:3. By this means, a high grinding effect will be reached.

In a preferred embodiment of the provided section insulator, the grooves are milled into the insulation body. This allows to efficiently produce the insulation body with a sharp scraping edge.

In a further another embodiment of the provided section insulator, the number of grooves is per meter in the driving direction at least 10, preferably at least 20 most preferably at least 25, which will further increase the grinding effect.

In a another embodiment of the provided section insulator, a ratio between a depth of the grooves seen in the height direction and a width of one of the grooves seen between its groove side walls is between 1:2 and 2:1, preferably 1:1, which will also increase the grinding effect.

In a further embodiment of the provided section insulator, the groove walls with the scraping edge include an inclination angle to the bottom surface between 70° and 110°, preferably 80° and 100° and preferably 90°. By this means, the ground abrasion will be effectively transported away from the grinding place and not plug the groove.

Even it is not necessary that each groove include a scraping edge at the bottom surface, it is preferred to provide each groove with one to get a high grinding effect.

In a further another embodiment of the section insulator, the grooves are filled with air through which the grinded abrasions can be transported to the outside.

In a another embodiment of the section insulator, a ratio between a width of the insulation body seen in cross direction and a width of one of the grooves seen between its groove side walls 2.5 or higher, preferably 3 or higher. By this means, a high density of the grooves can be reached leading not only to a high grinding effect but also to a longer way for a potential leakage current.

In a further embodiment of the section insulator, the insulation body is composed of a material having a hardness that is lower than a material of the pantograph, that is preferably plastic. By this means, the

pantograph will be protected from abrasions due to the grinding idea behind the present invention.

The above described characteristics, features and advantages of this invention as well as the manner and way how they are achieved will get further comprehensive based on following description of the

embodiments that will be explained in further detail in connection with the figures. It shows:

Fig. 1 a schematic view of a rail track for a train,

Fig. 2 a schematic view from the top on a section insulator for the rail track of Fig. 1,

Fig. 3a to 3c a three panel projection of an insulation body in the section insulator of Fig. 2,

Fig. 4a broken sectional view of a detail in the insulation body of Fig. 3a to 3c,

Fig. 4b a perspective view of the insulation body of Fig. 3a to 3c,

Fig. 5a to 5f examples for groove courses in the insulation body of Fig. 3a to 3c, and

Fig. 6a to 6f examples for groove sections in the insulation body of Fig. 3a to 3c. In the figures, equal technical elements will be provided with equal reference signs and described only one time. The figures are only of schematic nature and does in particular not disclose any real geometric dimension, unless it is not otherwise mentioned in the description.

Reference is made to Fig. 1 that shows an in a driving direction 1 extending rail track 2 including a rail 3 on which an electrically driven train can move guided by the rail 3. For an electric energy supply of the train, a catenary 4 is provided in a not referenced height above the track 3 that also extents in the driving direction 1. The train can take electric energy from the catenary 4 in a known way by a pantograph.

The catenary 4 is carried at a carrier, that is exemplary visualized in form of a ceiling 5 in Fig. 1. The ceiling 5 might be part of a tunnel of a bridge. The catenary 4 is carried at the ceiling 5 in a carrier distance 6.

Fig. 1 further shows the profile 7 of the catenary 4 in an enlarged way.

Seen in the profile 7, the catenary 4 is formed axially symmetric to a profile axis 8. Therein, the profile axis 8 runs in parallel to a height direction 9 of the rail track 2. Seen in the height direction 9, there is a cross arm 10 at the upper side of the catenary 4 from which two tensioning arms 12 extend against the height direction 9 and in a cross direction 11 that runs perpendicular to the driving direction 1 and perpendicular to the height direction 9. At an end of each tensioning arm 12 opposite to the cross arm 10, a clamping arm 13 is attached between which a contact wire 14 can be carried clamped by the

tensioning arms 12.

The catenary 4 shown in Fig. 1 is usually composed of a plurality of catenary sections that are seen in the profile 7 of Fig. 1 positioned via connection splice plates 15 exactly against each other and fixed to each other. The exact position is defined via form fits between the connection splice plates 15 and the catenary sections that is embodied in Fig. 1 as tounge/groove-connections 16. To fix the single catenary sections to each other, screws 17 can be screwed into the connection splice plates 15.

To facilitate the insertion of the contact wire 14 between the clamping arms 13, guideways 18 extend at a connection between the clamping arms 13 and the tensioning arms 12 in respectively against the cross direction 11, on which a not shown threading trolly can be moved. As the insertion of the contact wire 14 between the clamping arms 13 is not necessary to understand the present embodiment, further explanations hereto are omitted.

Reference is made to fig. 2 that shows a section insulator 19 in a schematic top view that is composed axis symmetrically to a symmetry axis 33.

It is known to separate the contact wire 14 from fig. 1 electrically into different sections, wherein the train mentioned above must be able to pass the resulting electric separation points. The section insulator 19 shown in fig. 2 connects the catenary 4 of a first wire section 20 with the catenary of a second wire section 21.

Seen in the driving direction 1, the section insulator 19 comprises a first connection equipment 22 with an input edge 23 and an output edge 24 that is located, seen in the driving direction 1, opposite to the first connection edge 23. The input edge 23 and the output edge 24 are connected via side edges 25 with each other. In the top view seen against the height direction 9, the first connection equipment 22 includes an basically triangular shape or a trapezoidal shape.

The catenary 4 of the first wire section is connected to the input edge 23 of the first connection equipment 22. The connection wire 14 that is guided through the catenary 4 of the first wire section 20 is guided into the zone of the first connection equipment 22. To the output edges 24, further catenaries 4 are connected that are arranged in parallel and with a distance to each other seen in the cross direction 11. To each of catenary 4 connected to the output edge 24 of the first connection equipment 22, an insulation body 26 is connected, wherein the both insulation bodies are placed, seen in the driving direction 1, with a displacement 27 against each other. To each insulation body 26 is again connected a catenary 4, wherein these catenaries 4 are again each connected to an insulation body 26. To these insulation bodies 26 further catenaries 4 are connected that are then connected to the output edge 24 of a second connection equipment 28. As the section

insulator 19 is formed axis symmetrically with respect to the symmetry axis 33, also the second connection equipment 28 is formed axially symmetrically to the first connection equipment 22 with respect to the symmetry axis 33. To the input edge 23 of the second connection equipment 28, the catenary 4 of the second wire section 21 is finally connected.

Seen in the height direction 9 below the connection equipments 22, 28 a contact wire is guided in the zone of each side edge 25, wherein these contact wires are named connection wires 29 to clearly differ them from the contact wires 14 carried by the catenaries 4. The connection wires 29 are indicated by dashed lines in fig. 2. Also the contact wires 14 in the catenaries 4 are indicated with dashed lines in fig. 2. As the section insulator 19 includes two insulation bodies 26 on each path between the two connection equipments 22, 28, the catenaries 4 between the insulation insulation bodies 26 are basically electrically neutral.

When a train passes the section insulator 19, its pantograph 30 that is indicated with dashed lines in fig. 2 will enter the section insulator 19 in the driving direction 1. When the pantograph 30 reaches the first of the insulation bodies 26, an electric contact of the pantograph 30 to the first wire section 20 will remain until the pantograph 30 reaches the second of the insulation bodies 26. In the zone of the first displacement 27, the pathograph 30 has still electric contact to the first wire sections 20. After leaving the second insulation body 26, the pantograph 30 has not any electric contact to either of the wire sections 20, 21. When the

pantograph 30 passes the third of the insulation bodies 26, it will get in contact with the second wire section 21, such that it can be electrically supplied by the second wire section 21 when moving further in the driving direction.

The section insulator 19 guarantees that there is no electrical contact between the first and second wire section 20, 21, such that both wire section 20, 21 can provide different power supply voltages.

The section insulator 19 as described above is only an example. It is principally sufficient to separate the two wire sections 20, 21 via one single section insulator 26. The section insulator 19 as described above however offers the advantage of a potential equalization, which would not be possible, if only one single section insulator 19 is used. The necessity of implementing a potential equalization is application

dependent.

Independent from the construction of the section insulator, to guarantee that the first and second wire section 20, 21 keep electrically isolated from each other, it must be secured that the first and second wire section 20, 21 will not be electrically shortcut against each other by abrasions, that might occur due to abrasions like coal dust that is distributed on the wire sections 20, 21 and the insulation bodies 26 via the pantograph 30.

To reduce the distribution of abrasions and thus reduce the risk of an electric shortcut, the insulation bodies 26 are specifically embodied, which will be explained hereinafter based on Figs. 3a to 3c that show a three panel projection of an insulation body 26 in the section insulator 19 of Fig. 2. In the driving direction 1, the insulation body 26 is drawn in a shortened way by using break lines 34.

Even the insulation body is explained based on the section insulator 19 of Fig. 2, it can be used in any suitable section insulator, like the section insulator according to WO 2012/065663 A2. Alternatively, the section insulator might be composed only of the insulator body 26 itself. The insulation body 26 has a maximum length extension 35 of

exemplary 1170 mm in the driving direction, a maximum cross

extension 36 of exemplary 15 mm in the cross direction and a maximum height extension 37 of exemplary 90 mm in the height direction.

Seen in the driving direction 1, the insulation body 26 includes a front wall 38 in the front and an end wall 39 opposite to the front wall 38. Seen in the driving direction 1 at the side of the front wall 38 spaced apart from it, there are positioning holes 40 and a fixing hole 41 through which the insulation body 26 can be fixed to one of the catenaries 4 in the section insulator 19. Therein, the location of the insulation body 26 relative to the catenary 4 is defined via form fits defined by the

positioning holes 40, while it is fixed to the catenary 4 via a force fit, like a screw, which can be fed through the fixing hole 41. A further fixing hole 41 is provided seen in the driving direction 1 at the end wall 39 spaced apart from it.

If the insulation body 26 would be used alone as section insulator, as indicated above as one technical possibility, the positioning holes 40 and the fixing hole 41 at the front wall 38 will directly effect as first

connection interface to connect the the insulation body 26 to the first current rail 20, whereas the further fixing hole 41 at the end wall 29 will directly effect as second connection interface to connect the the insulation body 26 to the second current rail 21. Otherwise, in case the section insulator 19 is more complex, as exemplary in fig. 2, the

connection interfaces will include further technical components. In the section insulator 19 the connection connection equipment 22, 28 effect as connection interface.

Seen in the height direction 9, the insulation body 26 includes a bottom side 42 at the lower end and a top side 43 opposite to the bottom side 42. At the bottom side 42, the insulation body 19 includes seen in the driving direction 1 a first receiving edge 44 starting from the front all 38 and running into the driving direction 1 and a second receiving edge 45 starting from the end wall 39 and running against the driving direction 1. Both receiving edges 44, 45 run starting from their respective wall 38, 39 also against the height direction 9 and effect thus that there will not be any edge, at which the pantograph 30 might hit, when entering the area of the insulation body 26. The first receiving edge 44 may have a first receiving length 46 of 74 mm, while the second

receiving edge 45 may have a second receiving length 47 of 80 mm.

The edge at the bottom side 42 between the two receiving edges 44, 45 is called contacting edge 48, where the pantograph 30 will mechanically contact the insulation body 26 when passing it. It has a contacting length 49 of around 1000 mm. As long as the pantograph 30

mechanically contacts the insulation body 26, it shall not have any electric contact to the both catenaries 4 between which the insulation body 26 is inserted.

However, due to abrasions, the before mentioned requirement my not be always fulfilled, because abrasions, like coal dust, are electrically conductible and may shortcut the both catenaries 4 via the contacting edge 48. To lower the risk for the electric shortcut, a leakage path is enlonged via a number of 29 grooves 50 that are milled into the bottom side 42 against the height direction.

The grooves 50 are positioned in parallel to each other, wherein each groove has a groove course 53 that runs seen in the cross direction 11 from a first insulation body side wall 51 to a second insulation body side wall 52 opposite to the first insulation body side wall 51, wherein the insulation body side walls 51, 52 limit the insulation body 26 in the cross direction 11 and the first insulation body side wall 51 is located before the second insulation body side wall 52. The grooves 50 are opened at the both insulation body side walls 51, 52.

The groove course 53 of each groove 50 might be basically arbitrarily formed, however with two restrictions.

As first restriction, each groove course 53 has an inclination angle 54 to the driving direction 1 higher than 140° but lower than 180° at the first insulation body side wall 51 or at the second insulation body side wall 52. In the present embodiment, the inclination angle 54 of the groove course to the driving direction 1 at the first insulation body side wall 51 is 155° in fact.

As second restriction relates to the groove walls. Each groove has seen driving direction 1 a front groove wall 55 that is aligned against the driving direction 1 and a rear groove wall 56 that is aligned in the driving direction 1. That are indicated in Fig. 3b, wherein not all front and rear groove walls 55, 56 are indicated with an own reference sign for the sake of completeness.

The front groove wall 55 of each groove 50 forms together with the bottom side 42 of the insulating body 26 a scraping edge 57 at the bottom surface 42, such that the scraping edge 57 is aligned to the front side of the groove 50 seen in driving direction 1. This scraping edge 57 is visualized by a cut view 58 along the groove course 53 that is partly visualized in Fig. 4a.

Each groove 50 has a groove width 59 of 5 mm and a groove height 60 of 5 mm. The groove walls 55, 56 of the grooves 50 are spaced from each other by 5 mm, and the front groove wall 55 of one groove 50 is spaced to the rear groove wall 56 of a successively following groove 50 by

10mm, when seen in the direction of the cut view 58.

That is, there is an area on the contacting edge 48 that is covered by the grooves 50. A ration between this area and a remaining area on the contacting edge 48 as nearly 1:2.

When the pantograph 30 passes the bottom side 42 of the insulation body 26, the scraping edges 57 of the grooves 50 grind the abrasions, like the coal dust into the grooves 50. Coal dust that is already in the grooves 50 will be pressed outwardly along the groove course 53 by coal dust that is subsequently ground. By this means, the coal dust is transported away from the grinding area such that an excessive

agglomeration of coal dust in the groove will be prevented. Fig. 4b shows a perspective view of the insulation body 26.

Reference is now made to Fig. 5a and 5b, that show a part of the bottom side 42 of the insulation body 26 in an alternative embodiment. Basically, the inclination angle 54 could be arbitrarily chosen, as long as it is below 140° and 180°. The difference between Fig. 5a and 5b is that in Fig. 5a, inclination angle 54 is lower compared to Fig.5b. The higher the

inclination angle 54 is, i.e. the more the groove course 53 is inclined antiparallel against the driving direction, the higher will be the pressing force, with which subsequently following coal dust will press coal dust already in the respective groove 50 out of it. Thus, the absolute value of the inclination angle 54 should be chosen as high as possible. Flowever, the higher the inclination angle 54 is, the longer the respective groove 50 will be. This means, the coal dust in the respective groove 50 will have a longer way to leave it, such that the inclination angle 54 cannot be chosen arbitrarily small. Good results have been achieved with inclination angles 54 higher than 155° but lower than 165°, preferably higher than 150° but lower than 160°.

The inclination angle 54 needs also not to be constant over the cross length 11. It can vary as shown in Fig. 5c and 5d with a sharp kink 61, which also needs not to be mathematically steady. Alternatively, as shown in Fig. 5e and 5f, the inclination angle 54 can also vary

mathematically steady without any kink 61. In every case, the mean value of the inclination angle 54 of the groove course 53 should be chosen dependent on the above described ranges for the above

inclination angle 54 at side walls 51, 52, i.e. higher than 140° but lower than 180°, preferably higher than 150° but lower than 177,5°. In Fig. 3a and 5a, the inclination angle 54 is constant resulting in a mean

inclination angle of 155°. In Fig. 3b, the mean inclination is respectively higher.

Flowever, if the groove course 53 has a maximum seen over the cross direction 11 as in Figs. 5c to 5e, then the mean value get zero out of the before mentioned ranges for the mean value of the inclination angle 54. Nevertheless, seen in the cross direction 11, the before mentioned inclination angle 54 should be separately fulfilled left and right from the maximum.

Now, the groove walls 55, 56 will be described in more detail with reference to figs. 6a to 6f. These figs show examplary embodiment for the grooves 50 in a sectional view.

The front groove wall 55 with the scraping edge 57 includes an

inclination angle 62 to the bottom surface 42 at the scraping edge 57. This inclination angle 62 is chosen in that the above mentioned abrasions will be effectively ground. Good results have been achieved with an inclination angle 62 between 70° and 110°, preferably 80° and 100° and preferably 90°. In Fig. 6a, 6b, 6d, 6e and 6f, the inclination angle 62 is around 90°, whereas in Fig. 6c, a value of around 75° is chosen for the inclination angle.

The grooves 50 are filled with air in the present embodiment to enable that the above mentioned abrasions can displace the air and enter into the grooves 50.

As the groove width 59 is 5 mm in the present embodiment and the maximum cross extension 36 of the insulation body 26 is 15 mm, between a width 36 of the insulation body 26 and the groove width 59 is 3. This ration shall be preferably chosen with at least 2.5.

The material of the insulation body 26 is plastic. As the pantograph 30 is made of a metal to conduct electrical current from the contact wire 14, the plastic of the insulation body 26 prevents that the pantograph 30 will be damaged when scraping the coal dust. Basically, the material of the insulation body 26 can be arbitrarily chosen. Flowever, the material should be chosen in that it has a hardness lower than than the material of the pantograph 30.

Claims

Patent Claims

1. Section insulator (19) for separating a first current rail section (20) from a second current rail section (21) that extend in a driving

direction (1) of a train comprising:

- an insulation body (26) extending in the driving direction (1), in a cross direction (11) perpendicular to the driving direction (1) and in a height direction (9) perpendicular to the cross direction (11) and the driving direction (1),

- a first connection interface (40, 41) located seen in the driving

direction (1) at the beginning (38) of the insulation body (26) for connecting the insulation body (26) to the first current rail (20),

- a second connection interface (41) located seen in the driving

direction (1) at the end (39) of the insulation body (26) for connecting the insulation body (26) to the second current rail (21),

- a contact surface (48) that is seen in the height direction (9) located at the bottom side (42) of the insulation body (26) for supporting a

pantograph (30) of the train,

- a first insulation body side wall (51) that defines a border of the insulation body (26) at one side in the cross direction (11),

- a second insulation body side wall (52) that defines the border of the insulation body (26) seen in the cross direction (11) opposite to the first insulation body side wall (51),

- a number of grooves (50) of more then ten that are formed at the contact surface (48) into the insulation body (26) having a groove course (23) running from the first insulation body side wall (51) to the second insulation body side wall (52), wherein the groove course (23) has an inclination angle (54) to the driving direction (1) that is higher than 140° but lower than 180° at at least on one of the first insulation body side wall (51) and the second insulation body side wall (52), and wherein the groove walls (55) in the grooves (50) that are aligned to the front side (38) of the insulation body (26) seen in driving direction (11) include a scraping edge (57) at the contact surface (48).

2. Section insulator (19) according to claim 1, wherein the inclination angle (54) at least on one of the first insulation body side wall (51) and the second insulation body (52) is higher than 155° but lower than 165°, preferably higher than 150° but lower than 160° and most

preferably 155°.

3. Section insulator (19) according to claim 1 or 2, wherein a mean value of the inclination angle (54) of the groove course (23) between the first insulation body side wall (51) to the second insulation body side wall (52) is higher than 140° but lower than 180°, preferably is higher than 150° but lower than 177,5° and most preferably 155°.

4. Section insulator (19) according to one of the preceding claims, wherein a ratio between an area of the contact surface (48) covered by the grooves (50) and a remaining area (61) of the contact surface (48) is between 1:2 and 1:4, preferably 1:3.

5. Section insulator (19) according to one of the preceding claims, wherein the grooves (50) are milled into the insulation body (26).

6. Section insulator (19) according to one of the preceding claims, wherein the number of grooves (50) is per meter in the driving

direction (1) at least 10, preferably at least 20 most preferably at least 25.

7. Section insulator (19) according to one of the preceding claims, wherein a ratio between a depth (60) of the grooves (50) seen in the height direction (9) and a width (90) of one of the grooves (50) seen between its groove side walls (55, 56) is between 1:2 and 2:1, preferably 1 :1.

8. Section insulator (19) according to one of the preceding claims, wherein each groove (50) include a scraping edge (57) at the contact surface (48).

9. Section insulator (19) according to claim 8, wherein the groove wall (55) with the scraping edge (57) includes an wall inclination angle (62) to the bottom surface between 70° and 110°, preferably 80° and 100° and most preferably 90°.

10. Section insulator (19) according to one of the preceding claims, wherein the grooves (50) are filled with air.

11. Section insulator (19) according to one of the preceding claims, wherein a ratio between a width(36) of the insulation body (26) seen in cross direction (11) and a width (59) of one of the grooves (50) seen between its groove side walls (55, 56) is 2.5 or higher, preferably 3 or higher.

12. Section insulator (19) according to one of the preceding claims, wherein the insulation body (26) is composed of a material having a hardness that is lower than a material of the pantograph (30).

13. Section insulator (19) according to claim 12, wherein the material is plastic.