Vacuum interrupter tube and tap changer

Abstract

A vacuum interrupter (1) for a tap changer comprises a hollow cylindrical metal shield (2) for shielding against external magnetic fields, which metal shield is disposed around at least part of a cylindrical lateral surface of the vacuum interrupter (1). The vacuum interrupter (1) further comprises a holder (4), which is disposed outside of the metal shield (2) and the vacuum interrupter (1) and at least partly coaxially surrounds the metal shield and the vacuum interrupter. The holder (4) has a plurality of holding elements (5, 6), which hold the metal shield (2) in position in accordance with the vacuum interrupter (1).

Description

[0001] The invention relates to a vacuum switching tube for a tap changer for switching between different taps of a transformer and to a tap changer with such a vacuum switching tube.

[0002] The use of vacuum switching tubes as switching elements in tap changers, especially load tap changers, for uninterrupted switching under load between winding taps of a tap transformer has been known in the art for decades, for example from publication WO9630922A1.

[0003] Vacuum interrupters are generally found in high-voltage technology in a wide variety of designs and applications, for example in circuit breakers. It is known that, depending on the current level, the vacuum interrupter can be affected by an external magnetic field. German patent DE 19518533A1 proposes a shielding device to protect the vacuum interrupter from this effect of external magnetic fields. German patent DE 33 29 212 discloses a vacuum interrupter according to the preamble of claim 1.

[0004] Such a magnetic field can be generated by a transformer, depending on its design and construction, and consequently can also affect the vacuum switching tubes of a tap changer. This external influence can negatively affect the service life of the vacuum switching tubes, as it can lead to asymmetrical contact wear and asymmetrical coating of the insulating gaps within the vacuum switching tube.

[0005] It is therefore an object of the present invention to provide an improved concept for a vacuum switching tube, by which the vacuum switching tube is shielded from the disturbing influence of a surrounding external magnetic field and safe operation of the tap changer is ensured.

[0006] This problem is solved by the respective subject matter of the independent claims. Further embodiments are the subject matter of the dependent claims.

[0007] The improved concept is based on the idea of ​​equipping the vacuum switching tube with a metallic shield against external magnetic fields.

[0008] According to the improved concept, a vacuum switching tube for a tap changer is specified, which includes a metallic shield against external magnetic fields and a mounting bracket.

[0009] The metallic shield is hollow and cylindrical and arranged around at least a portion of the cylindrical surface of the vacuum switching tube. Preferably, the hollow cylindrical shield is at least half the height of the cylindrical surface of the vacuum switching tube and is positioned centrally on the tube in its axial direction. The shield can be made of a single piece or multiple pieces and is made, for example, of soft iron.

[0010] The mounting bracket is located outside the metallic shielding and the vacuum switching tube and surrounds the metallic shielding and the vacuum switching tube at least partially coaxially. Preferably, the vacuum switching tube is surrounded coaxially by the mounting bracket by at least 240 degrees.

[0011] Furthermore, the bracket has several retaining elements which hold the metallic shielding in position depending on the vacuum switching tube.

[0012] According to at least one embodiment, the retaining elements comprise at least two radially inwardly projecting protrusions that form a stop for a first end and a second end of the metallic shielding.

[0013] This positions the metallic shielding axially on the vacuum switching tube, preferably in the center.

[0014] According to at least one further embodiment, at least one of the projections comprises a spacer arranged between the metallic shielding and the vacuum switching tube.

[0015] The spacer is designed as a wedge-shaped protrusion, arranged radially inward on at least one projection and extending axially along the vacuum switching tube. When the bracket is mounted, the spacer is positioned between the shield and the vacuum switching tube, preventing the shield from directly contacting the cylindrical surface of the vacuum switching tube.

[0016] According to at least one embodiment, the retaining elements further comprise at least one radially inwardly projecting pin which fits precisely into an opening in the metallic shielding.

[0017] This keeps the shield in position and prevents the shield from twisting relative to the vacuum switching tube.

[0018] According to at least one embodiment, the holder comprises at least one inwardly directed shoulder at a first end and at a second end, which is positively engaged with the vacuum switching tube.

[0019] The step can be formed radially around the ends of the bracket and / or radially segmented, i.e., consisting of individual steps that are spaced apart from each other and arranged radially at the ends of the bracket.

[0020] According to at least one embodiment, the holder comprises several radially inwardly extending struts at both its first and second ends, which bear in a form-fitting manner against the vacuum switching tube. The struts fix the holder axially to the vacuum switching tube.

[0021] According to at least one further embodiment, the bracket consists of at least two segments that are identical to each other and each has several transverse and longitudinal struts. The segments are preferably arranged rotated 180 degrees horizontally and vertically relative to each other.

[0022] According to at least one further embodiment, the vacuum switching tube comprises a retaining ring which is detachably mechanically connected to the holder, such that the retaining ring can be inserted into the holder and locked in it by twisting.

[0023] The retaining ring rests against the front of the vacuum switching tube and, through the locking mechanism, fixes the holder in the axial direction of the vacuum switching tube.

[0024] According to the improved concept, a tap changer, in particular a load tap changer, is also specified, which includes at least one vacuum switching tube according to the improved concept.

[0025] According to at least one embodiment of the tap changer, the tap changer includes a load changer comprising the vacuum switching tube, or a load selector comprising the vacuum switching tube.

[0026] The invention is explained in detail below with reference to exemplary embodiments and the drawings. Components that are identical, functionally identical, or have an identical effect may be provided with identical reference numerals. Identical components or components with identical function may be explained only with respect to the figure in which they first appear. The explanation is not necessarily repeated in the subsequent figures.

[0027] They show Figure 1 is a perspective view of an exemplary embodiment of a vacuum switching tube according to the improved concept; Figure 2 is a longitudinal section view of the vacuum switching tube made of Figure 1 Figure 3 shows a perspective view of an exemplary embodiment of a segment of a holder for a vacuum switching tube according to the improved concept; Figure 4 shows a perspective detail view of another exemplary embodiment of a vacuum switching tube according to the improved concept.

[0028] Figure 1 and 2 show a perspective and a longitudinal section view of an exemplary embodiment of a vacuum switching tube according to the improved concept.

[0029] The vacuum switching tube 1 has a housing with a switching chamber 8, which is made, for example, of ceramic, and two end-faced walls 9, which are made, for example, of metal. The switching chamber 8 is hollow and cylindrical, with a cylindrical outer surface. The end faces of the switching chamber 8 form an airtight seal.

[0030] The vacuum switching tube 1 has a fixed contact 11 and a contact 12 that is axially movable relative to the vacuum switching tube. The contacts 11 and 12 are arranged in the switching chamber 8. The vacuum switching tube 1 can be opened and closed by actuating the movable contact 12.

[0031] A hollow cylindrical, metallic shield 2 is arranged around a part of the vacuum switching tube 1, more precisely around a part of the cylindrical surface of the switching chamber 8, along an axis A centrally with respect to the height of the switching chamber 8.

[0032] A bracket 4 surrounds the vacuum switching tube 1 and the shield 2 coaxially from the outside by approximately 240 degrees. The remaining part of the vacuum switching tube 1 and the shield 2 is not touched by the bracket 4.

[0033] At the first end 41 and a second end 42 of the bracket 4, several radially inwardly extending struts 44 are arranged, which in the mounted state of the bracket 4 bear in a form-fitting manner against the vacuum switching tube 1 or the end-face walls 9 and thereby fix the bracket 4 with respect to the axis A.

[0034] The bracket 4 consists of two segments that are identical to each other and have several cross braces 13 and longitudinal braces 14. The two segments are arranged rotated 180 degrees horizontally and vertically relative to each other.

[0035] Figure 3 shows a perspective view of such a segment of the bracket 4 in detail.

[0036] The holder 4 or the segments have retaining elements with which they rest against the vacuum switching tube 1 or the switching chamber 8 and the walls 9 as well as against the shielding 2.

[0037] Several radially inwardly projecting projections 5 are arranged on the radially arranged longitudinal struts 14 at the level of a first end 21 and a second end 22 of the shielding 2. These form an upper and a lower stop for the shielding 2 and fix it with respect to axis A.

[0038] The adjacent projections 5, which are arranged at the level of the second end 22 of the shield 2 on the longitudinal struts 14, are partially connected to one another, forming additional partial struts 15. Spacers 16 are provided on the projections 5 that are connected to one another via partial struts 15. These spacers are designed as wedge-shaped protrusions that extend axially along the vacuum switching tube 1, taper towards the first end 41 of the bracket 4, and are arranged radially inside the partial struts 15 of the projections 5. When the bracket 4 is mounted, the wedge-shaped protrusions are arranged between the shield 2 and the vacuum switching tube 1, more precisely the switching chamber 8, such that the shield 2 does not rest directly on the cylindrical surface of the shield 2.

[0039] Another retaining element is a radially inwardly projecting pin 6, which is centrally located on one of the longitudinal struts 14 of the bracket 4. This pin 6 engages positively with an opening 23 in the shield 2. This prevents the shield 2 from rotating in relation to the vacuum switching tube 1.

[0040] The segments of the holder 4 each have an internal collar 43 with a shoulder 7 at their first end 41 and second end 42, which is arranged radially and inwards. The vacuum switching tube 1, or rather its end-face walls 9, abut the shoulders 7.

[0041] To stabilize the holder 4 on the vacuum switching tube 1, a cable tie 17 is arranged at the level of the collar 43 at the first end 41 and the second end 42 (see below). Figure 1 ).

[0042] Figure 4shows a perspective detail view of another exemplary embodiment of a vacuum switching tube according to the improved concept.

[0043] At the first end 41 of the bracket 4, a retaining ring 3 is arranged, which bears against the end face 9 at the first end 41. The retaining ring 3 is detachably mechanically connected to the bracket 4 according to the principle of a bayonet fitting, such that the retaining ring 3 can be inserted into the collar 43 at the first end 41 of the bracket 4 and locked in place by twisting. In this way, the bracket 4 is fixed with respect to the axis A.

[0044] It is assumed that the present disclosure and many of its accompanying advantages are understood from the foregoing description. Furthermore, it is obvious that various modifications to the shape, construction, and arrangement of the components can be made without deviating from the disclosed subject matter or without foregoing all material advantages. The described embodiments are merely illustrative, and such modifications are included in the following claims. It is understood that the invention is defined only by the following claims. REFERENCE MARK

[0045] 1 Vacuum switching tube 2 Shielding 3 Mounting ring 4 Bracket 5 Projection 6 Pin 7 Recess 8 Switching chamber 9 End wall 11 Fixed contact 12 Movable contact 13 Cross brace 14 Longitudinal brace 15 Partial brace 16 Spacer 17 Cable tie 21, 22 First end and second end of 2 23 Opening of 2 41, 42 First end and second end of 4 43 Collar of 4 44 Struts of 4

Claims

1. Vacuum interrupter (1) for a tap-change operation, the vacuum interrupter (1) comprising a metallic shield (2) from external magnetic fields, which is hollow-cylindrical in shape and is arranged around at least part of a cylindrical outer surface of the vacuum interrupter (1) a holder (4) which is arranged outside the metallic shielding (2) and the vacuum interrupter (1) and surrounds the latter at least partially coaxially, wherein the holder (4) has a plurality of retaining elements (5, 6), characterized in that the retaining elements comprise at least two radially inwardly projecting projections (5) which form a stop for a first end (21) and a second end (22) of the metallic shielding (2) .

2. The vacuum interrupter according to claim 1, wherein at least one of the protrusions (5) comprises a spacer (16) arranged between the metallic shield (2) and the vacuum interrupter (1).

3. Vacuum interrupter according to one of the previous claims, wherein the holding elements comprise at least one radially inwardly projecting pin (6), which projects positively into an opening (23) in the metallic shielding (2).

4. Vacuum interrupter according to one of the previous claims, wherein the holder (4) comprises, at a first end (41) and at a second end (42), in each case at least one radially circumferential and / or radially segmented and inwardly directed shoulder (7), which bears positively against the vacuum interrupter (1).

5. Vacuum interrupter according to the previous claim, wherein the holder (4) comprises at the first end (41) and at the second end (42) in each case a plurality of radially inwardly extending struts (44), which bear positively against the vacuum interrupter (1).

6. Vacuum interrupter according to one of the previous claims, wherein the holder (4) has a plurality of transverse struts (13) and longitudinal struts (14).

7. Vacuum interrupter according to one of the previous claims, the vacuum interrupter (1) further comprising a fastening ring (3) which is detachably mechanically connected to the holder (4) in such a way that the fastening ring (3) can be inserted into the holder (4) and can be locked in the latter by twisting.

8. Tap changer comprising a vacuum interrupter (1) according to one of claims 1 to 7.

9. Tap changer according to claim 8, wherein the tap changer comprises a diverter switch or a selector switch which comprises the vacuum interrupter (1).

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