Surge arrester which can be separated by moving the discharge column

Abstract

The invention relates to a surge arrester (1). The surge arrester (1) comprises a housing (3) which has a feed-through (15) having an electrical conductor (17), and comprises a discharge column (5) arranged in the housing (3). The discharge column (5) can be moved relative to the housing (3) along a longitudinal axis (21) of the discharge column (5) between a first end position in which a first end (39) of the discharge column (5) contacts the electrical conductor (17), and a second end position in which the discharge column (5) is electrically separated from the electrical conductor (17). The two electrical conductors (17) are axially positioned on each end (35, 27) of the discharge column (5).

Description

[0001] 2024PF00502

[0002] 1

[0003] Description

[0004] Surge arrester

[0005] The invention relates to a surge arrester.

[0006] Surge arresters are protective devices, for example for switchgear, which, in the event of overvoltages occurring, such as those caused by lightning strikes or malfunctions of other subsystems, divert these overvoltages to ground and thus protect other components of the switchgear.

[0007] WO 2012 / 168112 discloses a surge arrester comprising a discharge element, a control hood electrically connected to the discharge element, and a fluid-tight housing in which the discharge element and the control hood are arranged and which has two contacts, each electrically connecting the interior to the exterior of the housing. The discharge element and the control hood are designed to be movable relative to each other, whereby an electrical connection from one of the contacts via the discharge element to the other contact can be established or interrupted by the relative movement.

[0008] The invention is based on the objective of providing an improved surge arrester.

[0009] The problem is solved according to the invention by a surge arrester with the features of claim 1.

[0010] Advantageous embodiments of the invention are the subject of the dependent claims.

[0011] A surge arrester according to the invention comprises

[0012] - a housing that has a feedthrough with an electrical conductor, and 2024PF00502

[0013] 2

[0014] - a discharge column arranged in the housing, wherein

[0015] - the discharge column is displaceable relative to the housing along a longitudinal axis of the discharge column between a first end position in which a first end of the discharge column contacts the electrical conductor, and a second end position in which the discharge column is electrically separated from the electrical conductor.

[0016] A surge arrester according to the invention is designed to protect an electrical circuit from overvoltages by connecting a current path of the circuit to the electrical conductor of the surge arrester. An overvoltage is dissipated through the discharge column of the surge arrester. The surge arrester allows the electrical connection between the discharge column and the electrical conductor to be disconnected by moving the discharge column.

[0017] This allows the surge arrester to be deactivated in a simple and reliable manner by moving the discharge column, for example for testing or inspection purposes where an overvoltage should not be limited by the surge arrester.

[0018] One embodiment of a surge arrester according to the invention features a displacement device that can be manually operated from outside the housing and is designed to displace the discharge column between two end positions. For example, the displacement device comprises a push rod connected to the discharge column, which is guided fluid-tight through a housing wall and over which the discharge column can be displaced. This makes it possible to interrupt and later re-establish an electrical connection between the discharge column and the electrical conductor when the surge arrester housing is closed. This is particularly advantageous if the housing, for example in a gas-insulated switchgear, is fluid-tight and filled with an insulating gas, since it is not necessary to open the housing to disconnect the discharge column from the electrical conductor.

[0019] 3

[0020] A housing is required that can cause gas loss.

[0021] In a further embodiment of a surge arrester according to the invention, the discharge column comprises a stack of arrester elements with several stacked arrester elements and an electrically conductive contact element that is electrically connected to a first end of the arrester stack and forms the first end of the discharge column. For example, each arrester element is designed as a cylindrical varistor. A varistor exhibits a voltage-dependent electrical resistance. At low voltages, a varistor exhibits a very high electrical resistance and therefore acts like an insulator. Above a threshold voltage that depends on the material of the varistor, the electrical resistance of the varistor drops sharply, and the varistor exhibits good electrical conductivity. Therefore, varistors are suitable as components of a surge arrester.

[0022] Due to their manufacturing process, varistors have a maximum height and are therefore stacked on top of each other, so that two adjacent varistors are in mechanical and electrical contact and connected in series. The contact element of the discharge column enables the electrical connection of the discharge stack to the electrical conductor of the surge arrester.

[0023] In a further embodiment of a surge arrester according to the invention, the discharge column has a first end fitting located at the first end of the arrester stack and a second end fitting located at a second end of the arrester stack, and the arrester stack is clamped between the end fittings by tension elements. For example, the tension elements form a cage around the arrester stack that blocks displacement of the arrester elements perpendicular to the longitudinal axis of the discharge column. This makes it possible to stabilize the arrester stack by the tension elements and to press the arrester elements together to create an electrical 2024PF00502

[0024] 4

[0025] To improve contact between adjacent drain elements.

[0026] In a further embodiment of a surge arrester according to the invention, the first end fitting is made of an electrically conductive material, and the contact element is electrically connected to the first end of the arrester stack via the first end fitting. Thus, the first end fitting serves simultaneously to tension the tension elements and to electrically connect the arrester stack to the contact element of the surge arrester.

[0027] Another embodiment of the surge arrester according to the invention has an electrically conductive first shielding element that is fixedly arranged in the housing and surrounds the first end of the arrester stack and the first end fitting in the first end position of the arrester column. The first shielding element can shield electrical fields caused by the first end of the arrester stack in the first end position of the arrester column.

[0028] In a further embodiment of a surge arrester according to the invention, the first shielding element is designed as a tube-like guide for the first end fitting during displacements of the discharge column between its end positions. Thus, the first shielding element serves not only to shield electric fields but also to guide the arrester stack during its displacement.

[0029] In a further embodiment of a surge arrester according to the invention, the first shielding element is connected to the electrical conductor by an insulator tube made of an electrically insulating material, wherein, in the first end position of the discharge column, the insulator tube surrounds a section of the contact element extending between the first shielding element and the electrical conductor. The insulator tube connects the first shielding element to the electrical conductor. 2024PF00502

[0030] 5

[0031] The conductor of the surge arrester is attached and thus fixed in the housing.

[0032] Another embodiment of the surge arrester according to the invention has an electrically conductive second shielding element, which is fixedly arranged in the housing and, in the second end position of the arrester column, surrounds the second end of the arrester stack and the second end fitting. The second shielding element can shield electrical fields generated by the second end of the arrester stack.

[0033] In a further embodiment of a surge arrester according to the invention, the second shielding element is designed as a tube-like guide for the second end fitting during displacements of the discharge column between its end positions. Thus, the second shielding element serves not only to shield electric fields but also to guide the arrester stack during its displacement.

[0034] In a further embodiment of a surge arrester according to the invention, the second end fitting is made of an electrically conductive material and rests against the second shielding element. Furthermore, the second shielding element is connected to an electrically conductive housing wall of the housing. This establishes an electrical connection between the second end of the arrester stack and the housing wall via the second end fitting and the second shielding element. This connection makes it possible, in particular, to ground the second end of the arrester stack to a reference potential (earth potential) by grounding the housing wall to this reference potential. Thus, for example, no separate electrical connection needs to be brought out of the housing to ground the second end of the arrester stack.

[0035] The properties, features and advantages of this invention described above, as well as the manner in which these are achieved, are detailed in 2024PF00502.

[0036] 6

[0037] These will become clearer and more easily understood in connection with the following description of exemplary embodiments, which are explained in more detail in conjunction with the drawings. These show:

[0038] FIG 1 shows a perspective sectional view of a surge arrester with a discharge column in a first end position,

[0039] FIG 2 shows a perspective sectional view of the surge arrester shown in Figure 1 in a second end position of the discharge column.

[0040] Corresponding parts are marked with the same reference symbols in the figures.

[0041] Figure 1 (FIG 1 ) and Figure 2 (FIG 2 ) show an embodiment of a surge arrester 1 according to the invention. The surge arrester 1 comprises a housing 3, a discharge column 5 arranged in the housing 3, a sliding device 7, a first shielding element 9, a second shielding element 11 and an insulator tube 13.

[0042] The housing 3 is essentially designed as a hollow cylinder with closed ends. One end of the housing 3 has a fluid-tight feedthrough 15 with an electrical conductor 17. The conductor 17 is guided through an insulating washer 19 of the feedthrough 15, which is made of an electrically insulating material. Except for the feedthrough 15, the housing 3 is made of an electrically conductive material, for example, a metal.

[0043] The discharge column 5 is displaceable relative to the housing 3 along a longitudinal axis 21 of the discharge column 5 by means of the displacement device 7 between a first end position and a second end position. Figure 1 shows a 2024PF00502

[0044] Figure 2 shows a perspective sectional view of the surge arrester 1 in the first end position of the discharge column 5. Figure 2 shows a perspective sectional view of the surge arrester 1 in the second end position of the discharge column 5.

[0045] The discharge column 5 comprises a discharge stack 23, a first end fitting 25, a second end fitting 27, several pull elements 29 and an electrically conductive contact element 31.

[0046] The arrester stack 23 has several arrester elements 33 stacked on top of each other, each of which is designed as a cylindrical varistor.

[0047] The first end fitting 25 is made of an electrically conductive material and rests against a first end 35 of the surge arrester stack 23. The second end fitting 27 is made of an electrically conductive material and rests against a second end 37 of the surge arrester stack 23. The surge arrester stack 23 is clamped between the end fittings 25 and 27 by the tension elements 29. Each tension element 29 is, for example, designed as a pull rod, one end of which is connected to the first end fitting 25 and the other end of which is connected to the second end fitting 27. The tension elements 29 press the surge arrester elements 33 together and form a cage around the surge arrester stack 23, which blocks any displacement of the surge arrester elements 33 perpendicular to the longitudinal axis 21 of the surge column 5.

[0048] The contact element 31 forms a first end 39 of the discharge column 5 and is electrically connected to the first end fitting 25 and via the first end fitting 25 to the first end 35 of the discharge stack 23.

[0049] The conductor 27 has a recess 41 on one surface facing the discharge column 5, corresponding to the contact element 31, into which the contact element 31 is inserted in the first 2024PF00502

[0050] 8

[0051] The discharge column 5 is retracted to its final position, so that the contact element 31 contacts the conductor 27. In the second end position of the discharge column 5, the contact element 31 is disconnected from the conductor 27.

[0052] The first shield element 9 is made of an electrically conductive material and is designed as a tube-like guide for the first end fitting 25 during displacements of the discharge column 5 between its end positions.

[0053] Furthermore, the first shielding element 9 is designed to shield electric fields caused by the first end 35 of the drain stack 23 in the first end position of the discharge column 5.

[0054] The insulator tube 13 is made of an electrically insulating material and, in the first end position of the discharge column 5, surrounds a section of the contact element 31 running between the first shielding element 9 and the conductor 27. The first shielding element 9 is attached to the conductor 27 by means of the insulator tube 13.

[0055] The second shielding element 11 is made of an electrically conductive material, designed as a tube-like guide for the second end fitting 27 during displacements of the discharge column 5 between its end positions, and connected to an electrically conductive housing wall 43 of the housing 3. Furthermore, the second shielding element 11 is designed to shield electric fields generated by the second end 37 of the discharge stack 23.

[0056] The displacement device 7 can be manually operated from outside the housing 3 and is designed to move the drain column 5 between its two end positions. The displacement device 7 has a push rod 45 connected to the drain column 5, which is guided fluid-tight through the housing wall 43 of the housing 3. The drain column 5 can be moved via the push rod 45. The displacement device 7 has an external mounting 2024PF00502

[0057] arranged (not shown in detail) manually operable actuating element, by the actuation of which the discharge column 5 can be moved via the push rod 45 .

[0058] For example, the actuating element is designed as a hand crank.

[0059] During operation of the surge arrester 1, the housing wall 43 is connected to an electrical reference potential (earth potential). Through the electrical connection of the housing wall 43 to the second end 37 of the arrester stack 23 via the second shielding element 11 and the second end fitting 27, the second end of the arrester stack 23 is also connected to the reference potential.

[0060] In normal operation of the surge arrester 1, the discharge column 5 is in the first end position and the conductor 27 is connected to a high-voltage potential. Through the electrical connection of the conductor 27 to the first end 35 of the arrester stack 23 via the contact element 31 and the first end fitting 25, the first end 35 of the arrester stack 23 is also connected to the high-voltage potential. In the event of an overvoltage, that is, when the high-voltage potential exceeds a voltage threshold, the surge arrester 1 discharges the overvoltage to a ground electrically connected to the housing wall 43.

[0061] During a test or verification operation of the surge arrester 1, the discharge column 5 is moved into the second end position via the displacement device 7. This interrupts the electrical connection of the conductor 27 with the discharge column 5.

[0062] Although the invention has been further illustrated and described in detail by means of preferred embodiments, the invention is not limited by the disclosed examples and other variations can be devised by a person skilled in the art. 2024PF00502

[0063] 10

[0064] can be derived from this without leaving the scope of protection of the invention.

Claims

2024PF00502 11 Patent claims 1. Surge arrester ( 1 ) , comprising - a housing (3) which has a feedthrough (15) with an electrical conductor (17), and - a discharge column (5) arranged in the housing (3) , wherein - the discharge column (5) is displaceable relative to the housing (3) along a longitudinal axis (21 ) of the discharge column (5) between a first end position in which a first end (39) of the discharge column (5) contacts the electrical conductor ( 17 ) and a second end position in which the discharge column (5) is electrically separated from the electrical conductor ( 17 ).

2. Surge arrester ( 1 ) according to claim 1 with a displacement device (7 ) which can be manually operated from outside the housing (3) and is designed to displace the discharge column (5) between the two end positions .

3. Surge arrester ( 1 ) according to claim 2, wherein the displacement device (7 ) has a push rod (45) connected to the discharge column (5), which is guided fluid-tight through a housing wall (43) of the housing (3) and over which the discharge column (5) is displaceable .

4. Surge arrester ( 1 ) according to one of the preceding claims, wherein the discharge column (5) has a A stack of arresters (23) with several stacked arrester elements (33) and an electrically conductive contact element (31) that is electrically connected to a first end (35) of the drain stack (23) is connected and forms the first end (39) of the drain column (5).

5. Surge arrester ( 1 ) according to claim 4, wherein each arrester element (33) is designed as a cylindrical varistor . 2024PF00502 12 6. Surge arrester ( 1 ) according to claim 4 or 5, wherein the discharge column (5) has a first end fitting (25) abutting the first end (35) of the arrester stack (23) and a second end fitting (27 ) abutting a second end (37 ) of the arrester stack (23) and the arrester stack (23) is clamped between the end fittings (25, 27 ) by tension elements (29 ).

7. Surge arrester ( 1 ) according to claim 6, wherein the tension elements (29) form a cage around the arrester stack (23) which blocks a displacement of the arrester elements perpendicular to the longitudinal axis (21 ) of the discharge column (5 ).

8. Surge arrester ( 1 ) according to claim 6 or 7, wherein the first end fitting (25) is made of an electrically conductive material and the contact element (31 ) is electrically connected to the first end (35) of the arrester stack (23) via the first end fitting (25 ).

9. Surge arrester ( 1 ) according to one of claims 6 to 8 with an electrically conductive first shielding element ( 9 ) which is fixedly arranged in the housing (3) and surrounds the first end (35) of the arrester stack (23) and the first end fitting (25) in the first end position of the discharge column (5 ).

10. Surge arrester ( 1 ) according to claim 9, wherein the first shielding element ( 9) is designed as a tube-like guide for the first end fitting (25) during displacements of the discharge column (5) between its end positions .

11. Surge arrester ( 1 ) according to claim 9 or 10, wherein the first shielding element ( 9 ) is connected to the electrical conductor ( 17 ) by an insulator tube ( 13 ) made of an electrically insulating material, wherein the insulator tube ( 13 ) surrounds a section of the contact element (31 ) extending between the first shielding element ( 9 ) and the electrical conductor ( 17 ). 2024PF00502 13 12. Surge arrester ( 1 ) according to one of claims 6 to 11 with an electrically conductive second Shield element ( 11 ) which is fixedly arranged in the housing ( 3 ) and in the second end position of the discharge column ( 5 ) surrounds the second end ( 37 ) of the discharge stack ( 23 ) and the second end fitting ( 27 ).

13. Surge arrester ( 1 ) according to claim 12 , wherein the second shielding element ( 11 ) is designed as a tube-like guide for the second end fitting ( 27 ) during displacements of the discharge column ( 5 ) between its end positions .

14. Surge arrester ( 1 ) according to claim 12 or 13, wherein the second end fitting ( 27 ) is made of an electrically conductive material and rests against the second shielding element ( 11 ) and the second shielding element ( 11 ) is connected to an electrically conductive housing wall ( 43 ) of the housing ( 3 ).

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