Tap changeover stand

Abstract

To provide a tap changeover stand having high electrical insulation properties.SOLUTION: A tap changeover stand base 1 used in a transformer, includes: a stand portion 2 having a plurality of tap terminals 3; and an insulating fixing leg portion 4 having one end portion provided on the stand portion 2 and the other end fixed to an earth terminal.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a tap-changing base. [Background technology]

[0002] Conventionally, an insulating tap changer has been used to change taps in a transformer (see Patent Documents 1 and 2). Such an insulating tap changer is attached to an earth terminal provided on a core fastening fixture for fixing a wound core having a coil. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-112060 [Patent Document 2] Japanese Patent Application Publication No. 6-112061 Summary of the Invention [Problem to be solved by the invention]

[0004] Since the tap changer has a tap terminal, electrical insulation between the tap terminal and the earth terminal must be ensured. However, Patent Documents 1 and 2 do not fully consider electrical insulation between the tap terminal and the earth terminal.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to provide a tap changer base having high electrical insulation properties. [Means for solving the problem]

[0006] The tap changer of the present invention is a tap changer for use in a transformer, and comprises a base portion having a plurality of tap terminals, and an insulating fixing leg portion having one end provided on the base portion and the other end fixed to an earth terminal. Effect of the Invention

[0007] According to the present invention, a tap changer base having high electrical insulation properties can be provided. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view of the tap changing base according to the first embodiment. [Diagram 2] 1A and 1B are a front view and a bottom view of a tap changing base according to a first embodiment. [Diagram 3] FIG. 11 is a perspective view of a tap changing block according to a second embodiment. [Figure 4] 11A and 11B are a front view and a bottom view of a tap changing base according to a second embodiment. [Diagram 5] FIG. 4C is an enlarged cross-sectional view of the dashed ellipse portion of FIG. 4B. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the present invention will be described with reference to the drawings showing an embodiment thereof.

[0010] (Embodiment 1) Fig. 1 is a perspective view of a tap changer table 1 according to embodiment 1, and Fig. 2 is a front view and a bottom view of the tap changer table 1 according to embodiment 1. Fig. 2A is a front view of the tap changer table 1, and Fig. 2B is a bottom view. For convenience of explanation, embodiment 1 will be explained taking a single-phase tap changer table 1 as an example.

[0011] The tap changer table 1 is used in an oil-filled transformer. The tap changer table 1 is installed, for example, in a container (tank) containing insulating oil in the oil-filled transformer. The tap changer table 1 includes a base part 2, a plurality of tap terminals 3, and an attachment part 4 (fixed leg part). The tap changer table 1 according to this embodiment changes the tap in a no-load, no-voltage state.

[0012] The base 2 is made of a thermoplastic resin. The thermoplastic resin has heat resistance, oil resistance, and electrical insulation properties. The thermoplastic resin is, for example, a polyamide resin, a PPS (polyphenylene sulfide) resin, or the like. The thermoplastic resin may be, for example, a thermoplastic engineering plastic (engineering plastic) or a super engineering plastic, and may contain a reinforcing agent such as glass fiber or an inorganic filler.

[0013] The base 2 is plate-shaped. More specifically, the base 2 includes two rectangular portions of different lengths, which are arranged in the same plane and are connected at their middle portions. A reinforcing rib 21 is provided along the edge of the base 2. The reinforcing rib 21 protrudes in the thickness direction of the base 2.

[0014] The shorter of the two rectangular portions of the base portion 2 is provided with an attachment portion 4. The attachment portions 4 are connected to both ends of the shorter rectangular portion. Each attachment portion 4 has the same shape and fixes the tap changer base 1 (base portion 2) to, for example, an earth terminal (not shown) of a core fastening fixture for fixing a wound core.

[0015] The tap terminal 3 is made of, for example, brass, and is a so-called insert metal fitting. The base 2 is provided with a plurality of bosses 22 penetrating the base 2 in the thickness direction. Each boss 22 is cylindrical, with both ends of the boss 22 protruding from the corresponding two main surfaces of the base 2, and each boss 22 is provided with a tap terminal 3. Each tap terminal 3 is a terminal used to connect a tap wire drawn from a tap of a transformer or the like, or to fix a connection piece that electrically connects a plurality of tap wires.

[0016] The tap terminal 3 has a male threaded portion 31, a female threaded portion 32, and a cap nut 33. More specifically, the cap nut 33 having a cylindrical shape with a bottom is fitted inside the boss 22, and the female threaded portion 32 is formed on the cap nut 33. Therefore, in the tap terminal 3, the male threaded portion 31 protrudes from one main surface of the base portion 2, and the female threaded portion 32 opens from the other main surface opposite to the one main surface. That is, the tap terminal 3 penetrates the base portion 2 in the thickness direction.

[0017] Each mounting portion 4 is substantially rectangular, extends in a direction away from the other main surface of the base portion 2 and away from each other, and has its end bent parallel to the base portion 2. That is, the mounting portion 4 has an inclined portion 41 that extends outward from the base portion 2 at an angle with respect to the thickness direction of the base portion 2, and a parallel portion 42 that is parallel to the base portion 2. One end of the inclined portion 41 is connected to an end of the shorter strip-shaped portion of the base portion 2, and the parallel portion 42 is connected to the other end of the inclined portion 41.

[0018] The mounting portion 4 is made of a thermoplastic resin, which has heat resistance, oil resistance, and electrical insulation properties. That is, like the base portion 2, the mounting portion 4 is made of a thermoplastic resin such as a polyamide resin or a PPS (polyphenylene sulfide) resin.

[0019] A reinforcing rib 44 is provided along the edge of the mounting portion 4. The reinforcing rib 44 protrudes in the thickness direction of the mounting portion 4 and is connected to the reinforcing rib 21 of the base portion 2. A boss 43 is provided in the center of the parallel portion 42 and is used when attaching the tap changer table 1 to the earth terminal of the core fastening bracket. The tap changer table 1 is fixed by inserting a bolt (not shown) into the boss 43 and screwing it to the earth terminal.

[0020] In the tap changer base 1 according to the first embodiment, the base portion 2 and the mounting portion 4 are integrally molded. Both the base portion 2 and the mounting portion 4 are made of a thermoplastic resin and are manufactured by, for example, injection molding the thermoplastic resin.

[0021] As described above, in the tap changer 1 of embodiment 1, the mounting portion 4 is made of a thermoplastic resin with excellent insulating properties, thereby improving the electrical insulation between the earth terminal of the core fastening bracket and the tap terminal 3.

[0022] Furthermore, in the tap changer base 1 of embodiment 1, the mounting portion 4 (inclined portion 41) is arranged at an angle to the base portion 2, so that the creepage distance between the earth terminal and the tap terminal 3 can be extended compared to when it is arranged vertically, thereby further improving the electrical insulation.

[0023] In the tap changer table 1 according to the first embodiment, the base portion 2 and the mounting portion 4 are integrally molded as described above. Therefore, the base portion 2 and the mounting portion 4, i.e., the tap changer table 1, can be manufactured by, for example, injection molding, which not only achieves a significant cost reduction but also increases the design freedom. Furthermore, the number of steps required for assembling the tap changer table 1 can be reduced, and the tap changer table 1 can be made compact.

[0024] Furthermore, in the tap changer base 1 according to the first embodiment, as described above, the reinforcing rib 44 of the mounting portion 4 is continuous with the reinforcing rib 21 of the base portion 2. This makes it possible to increase the strength of the tap changer base 1.

[0025] In the above, the case where the base portion 2 and the mounting portion 4 are integrally molded has been described as an example, but the present invention is not limited to this. It goes without saying that the effects of the present invention can be achieved even in a configuration where the base portion 2 and the mounting portion 4 are separate members and the mounting portion 4 is attached to the base portion 2 by screwing or the like.

[0026] (Embodiment 2) Fig. 3 is a perspective view of the tap changer table 1A according to embodiment 2, and Fig. 4 is a front view and a bottom view of the tap changer table 1A according to embodiment 2. Fig. 4A is a front view of the tap changer table 1A, and Fig. 4B is a bottom view. In embodiment 2, a three-phase tap changer table 1A will be described as an example.

[0027] The tap changer base 1A is used in an oil-filled transformer, as in the first embodiment, and includes a base portion 2A, a plurality of tap terminals 3A, and an attachment portion 4A (fixing leg portion). Figures 3 and 4 show a case in which a pair of tap terminals 3A are connected by a connection piece P. The connection piece P is fixed to the pair of tap terminals 3A by a nut.

[0028] The base 2A is plate-shaped and made of a thermoplastic resin such as polyamide resin or PPS resin. More specifically, the base 2A has a semicircular portion and a semi-elliptical portion having a smaller diameter than the semicircular portion, and the semicircular portion and the semi-elliptical portion are arranged in the same plane. The semi-elliptical portion is connected to the center of the linear edge of the semicircular portion. The base 2A is provided with reinforcing ribs 21A along the edge. The reinforcing ribs 21A are provided to protrude in the thickness direction of the base 2.

[0029] The semicircular portion of the base 2A is provided with a mounting portion 4A. The mounting portions 4A are connected to both ends of the linear edge of the semicircular portion. Each mounting portion 4A has the same shape and fixes the tap changer base 1A (base 2A) to an earth terminal (not shown) of a core fastening fixture for fixing a wound core.

[0030] The tap terminal 3A is made of, for example, brass, and is a so-called insert metal fitting. A plurality of bosses 22A penetrating the base 2A in the thickness direction are protrudingly provided on the semicircular portion and the semi-elliptical portion of the base 2A, and a tap terminal 3A is provided on each boss 22A. The tap terminal 3A has a male thread portion 31A, a female thread portion 32A, and a cap nut 33A. The tap terminal 3A and the boss 22A are the same as the tap terminal 3 and the boss 22 of the first embodiment, and detailed description thereof will be omitted.

[0031] The mounting portion 4A is substantially rectangular, extends in a direction away from the base portion 2A, and has an end bent parallel to the base portion 2A. That is, the mounting portion 4A has a vertical portion 41A that extends along the thickness direction of the base portion 2A, i.e., perpendicular to the main surface of the base portion 2A, and a parallel portion 42A that is parallel to the base portion 2A. One end of the vertical portion 41A is connected to the base portion 2A, and the parallel portion 42A is connected to the other end of the vertical portion 41A. The convex corner at the tip of the parallel portion 42A is R-chamfered.

[0032] The mounting portion 4A is made of a thermoplastic resin that has heat resistance, oil resistance, and electrical insulation properties. That is, like the base portion 2A, the mounting portion 4A is made of a thermoplastic resin such as a polyamide resin or a PPS resin.

[0033] A reinforcing rib 44A is provided along the edge of the mounting portion 4A. The reinforcing rib 44A protrudes in the thickness direction of the mounting portion 4A and is connected to the reinforcing rib 21A of the base portion 2A. A boss 43A is provided in the center of the parallel portion 42A and is used to attach the tap changer base 1A to the earth terminal of the core fastening bracket. The tap changer base 1A is fixed by inserting a bolt (not shown) into the boss 43A and screwing it to the earth terminal.

[0034] In addition, in the tap changer base 1A according to the second embodiment, the attachment portion 4A is provided with a concave-convex portion 411. Fig. 5 is an enlarged cross-sectional view of the dashed oval portion in Fig. 4B. The uneven portion 411 is formed on the vertical portion 41A and extends in a direction intersecting the longitudinal direction of the mounting portion 4A (vertical portion 41A). In the uneven portion 411, the distance between adjacent convex portions (W in FIG. 5) is 1 mm or more. The distance W between adjacent convex portions of the uneven portion 411 is, for example, 1 mm to 2 mm.

[0035] In the tap changer base 1A according to the second embodiment, the base portion 2A and the attachment portion 4A are integrally molded. Both the base portion 2A and the attachment portion 4A are made of a thermoplastic resin and are manufactured by, for example, injection molding.

[0036] As described above, in the tap changer base 1A of embodiment 2, the mounting portion 4A is made of a thermoplastic resin with excellent insulating properties, thereby improving the electrical insulation between the earth terminal of the core fastening bracket and the tap terminal 3A.

[0037] In the tap changer table 1A according to the second embodiment, the base portion 2A and the mounting portion 4A are integrally molded as described above. Therefore, the tap changer table 1 can be manufactured by, for example, injection molding, which not only significantly reduces costs but also increases design freedom. Furthermore, the number of steps required for assembling the tap changer table 1A can be reduced, and the tap changer table 1A can be made compact.

[0038] In the tap changer base 1A according to the second embodiment, as described above, the mounting portion 4A (vertical portion 41A) is formed with the uneven portion 411, and the interval W between the adjacent protrusions in the uneven portion 411 is 1 mm or more. This makes it possible to extend the creepage distance between the earth terminal and the tap terminal 3A, and further improve the electrical insulation.

[0039] In the above, the case where the base 2A and the mounting portion 4A are integrally molded has been described as an example, but the present invention is not limited to this. It goes without saying that the effects of the present invention can be achieved even in a configuration where the base 2A and the mounting portion 4A are separate members and the mounting portion 4A is attached to the base 2A by screws or the like.

[0040] In the above, the mounting portion 4A (vertical portion 41A) is provided perpendicular to the base portion 2A, but the present invention is not limited to this, and the mounting portion 4A may be provided at an angle to the base portion 2A as in embodiment 1. In this case, the creepage distance between the earth terminal and the tap terminal 3A is extended, thereby improving electrical insulation.

[0041] The same parts as those in the first embodiment are given the same reference numerals and detailed explanations are omitted.

[0042] The technical features (constituent elements) described in the first and second embodiments can be combined with each other, and by combining them, new technical features can be arrived at. The embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the scope and meaning equivalent to the claims.

[0043] The matters described in each embodiment can be combined with each other. In addition, the independent claims and dependent claims described in the claims can be combined with each other in any and all combinations regardless of the citation format. Furthermore, the claims use a format in which a claim cites two or more other claims (multiple claim format), but this is not limited to this. The claims may also be written in a format in which a multiple claim cites at least one other multiple claim (multi-multi claim). [Explanation of symbols]

[0044] 1,1A: tap changer base, 2,2A: base portion, 3,3A: tap terminal, 4,4A: mounting portion (fixed leg portion), 411: uneven portion

Claims

1. A tap changing table for use in a transformer, comprising: A base portion having a plurality of tap terminals; an insulating fixing leg part, one end of which is provided on the base part and the other end of which is fixed to a ground terminal; A tap changer comprising:

2. The base portion has a plate shape, 2. The tap changer base according to claim 1, wherein the fixing leg extends obliquely relative to the base portion.

3. The tap changer base according to claim 1 , further comprising an uneven portion provided on the fixed leg and extending in a direction intersecting with a longitudinal direction of the fixed leg.

4. 2. The tap changer base according to claim 1, wherein the fixing leg is made of a thermoplastic resin.

5. The base is made of a thermoplastic resin, The tap changer base according to claim 1 , wherein the base portion and the fixing leg portion are integrally formed.

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