Tap changer

Abstract

The present invention provides a tap changer that can prevent short circuits from occurring between tap terminals due to air accumulating on the underside of the tap changer. [Solution] A tap changer 1 used in a transformer in which insulating oil is stored inside, comprising a base portion 2 having a plurality of mounting seats 22 for tap terminals 3, the base portion 2 having at least one air vent hole 26 in the center between the mounting seats 22.

Description

Technical Field

[0001] The present invention relates to a tap changer stand.

Background Art

[0002] Conventionally, an insulating tap changer stand for switching taps in a transformer has been used. Such an insulating tap changer stand is attached to an earth terminal provided on a core clamping metal fitting for fixing a wound core provided with a coil. (See Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the case of manufacturing an oil-filled transformer using insulating oil, after placing the transformer body with the tap changer stand attached to the terminals of the coil into the tank, insulating oil is poured into the tank. After the oil injection is completed, degassing is performed by evacuation to remove the air remaining in the insulating oil. However, when performing degassing, air may adhere to and accumulate on the lower surface of the tap changer stand. Air has better electrical conductivity than insulating oil, and if air accumulates between the tap terminals on the lower surface of the tap changer stand, there is a risk of a short circuit occurring between the tap terminals through such air.

[0005] However, in Patent Document 1, no consideration has been made for such a problem and it cannot be dealt with.

[0006] The present invention has been made in view of such circumstances, and an object thereof is to provide a tap changer stand that can prevent a short circuit from occurring between tap terminals due to air accumulating on the lower surface of the tap changer stand when manufacturing a transformer. [Means for solving the problem]

[0007] The tap changing stand according to the present invention is a tap changing stand used in a transformer in which insulating oil is stored inside, and comprises a base portion having a plurality of mounting seats for tap terminals, wherein at least one air vent hole is formed in the center of the base portion between the mounting seats. [Effects of the Invention]

[0008] According to the present invention, it is possible to prevent short circuits from occurring between tap terminals due to air accumulating on the underside of the tap changer during the manufacturing of a transformer. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view of the tap changer according to this embodiment. [Figure 2] This is a front view of a tap changer. [Figure 3] This is a plan view of a tap changer. [Figure 4] This is a bottom view of the tap changer. [Figure 5] This is a cross-sectional view taken along the line V-V in Figure 4. [Modes for carrying out the invention]

[0010] The present invention will be described below with reference to the drawings illustrating its embodiments.

[0011] Figure 1 is a perspective view of the tap changer 1 according to this embodiment, and Figures 2 to 4 are the front view, top view, and bottom view of the tap changer 1 according to this embodiment. Figure 2 is a front view of the tap changer 1, Figure 3 is a top view of the tap changer 1, and Figure 4 is a bottom view of the tap changer 1. For the sake of explanation, this embodiment will be described using a single-phase tap changer 1 as an example.

[0012] The tap changer 1 is used in an oil-filled transformer in which insulating oil is stored internally. The tap changer 1 is installed, for example, inside the container (tank) containing the insulating oil in the oil-filled transformer. The tap changer 1 comprises a base 2, a plurality of tap terminals 3, and mounting legs 4. The tap changer 1 according to this embodiment switches taps under no-load, no-voltage conditions.

[0013] The base portion 2 is made of a thermoplastic resin. The thermoplastic resin has heat resistance, oil resistance, and electrical insulation properties. Examples of thermoplastic resins include polyamide resin and PPS (polyphenylene sulfide) resin. The thermoplastic resin may also be, for example, a thermoplastic engineering plastic or a super engineering plastic, and may contain reinforcing agents such as glass fibers or inorganic fillers.

[0014] The base portion 2 is a roughly rectangular plate shape. More specifically, the base portion 2 has two long sides of different lengths, with steps formed on both short sides. Reinforcing ribs 21 are provided along the edges of the base portion 2. The reinforcing ribs 21 protrude in the thickness direction of the base portion 2 at its edges.

[0015] Furthermore, the base portion 2 is provided with a plurality of mounting seats 22, which are bosses that penetrate the base portion 2 in the thickness direction. Each mounting seat 22 is hollow disc-shaped, and a tap terminal 3 is attached to each mounting seat 22. One end face of each mounting seat 22 protrudes from the upper surface 23 of the base portion 2, and the other end face protrudes from the lower surface 24 of the base portion 2.

[0016] In the tap changer stand 1 according to this embodiment, six mounting seats 22 are provided on the base 2, and two rows of three mounting seats 22 each (hereinafter referred to as mounting seat 22 rows) are provided parallel to each other with a gap in the width direction of the base 2. Furthermore, the two mounting seat 22 rows are offset from each other in the length direction. A gap is formed between the mounting seats 22 in each row.

[0017] Six air vent holes 26 are formed between two rows of mounting seats 22. Each air vent hole 26 is disposed between the mounting seats 22 of one row of mounting seats 22 and the mounting seats 22 of the other row of mounting seats 22, and is formed corresponding to such a mounting seat 22 in the vicinity of the mounting seat 22.

[0018] Each air vent hole 26 has the shape of the corresponding mounting seat 22, that is, the shape of an identification symbol for identifying the tap terminal 3. Here, the shape of the identification symbol is, for example, a number, an alphabet, a Greek letter, etc. In the following, for the sake of convenience of explanation, the case where the air vent hole 26 has the shape of a number will be taken as an example for explanation. That is, in the tap switching base 1 according to the present embodiment, the six air vent holes 26 have the shape of a series of numbers.

[0019] As described above, the tap terminal 3 is attached to each mounting seat 22. The tap terminal 3 is made of, for example, brass (yellow brass) and is a so-called insert fitting. 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 connecting piece for electrically connecting a plurality of tap wires.

[0020] Further, the tap terminal 3 has a male screw portion 31, a female screw portion 32 (see FIG. 4), and a nut 33. Specifically, the nut 33 having a bottomed cylindrical shape is fitted into the mounting seat 22, and the female screw portion 32 is formed on the inner peripheral surface of the bottom of the nut 33. Therefore, the male screw portion 31 of the tap terminal 3 protrudes from the upper surface 23 of the base portion 2. Further, the nut 33 opens from the lower surface 24 of the base portion 2, and the female screw portion 32 is formed on the inner wall of the nut 33. Therefore, each tap terminal 3 penetrates the base portion 2 in the thickness direction.

[0021] Furthermore, six air vent holes 26 are formed in the central portion of the base portion 2. That is, the base portion 2 is provided with the air vent holes 26 as many as the number of the mounting seats 22 (tap terminals 3). Each air vent hole 26 communicates with the base portion 2 in the thickness direction. In the following, the case where there are six air vent holes 26 will be taken as an example for explanation.

[0022] Furthermore, the base portion 2 has two through holes 25 facing each other in a diagonal direction. The through holes 25 are circular in shape and penetrate the base portion 2 in the thickness direction.

[0023] Figure 5 is a cross-sectional view taken along the line V-V in Figure 4. The lower surface 24 of the base portion 2 has recesses 27 that are open downwards. The recesses 27 are circular and are formed at positions corresponding to each air vent 26. In other words, there are six recesses 27 on the lower surface 24, and an air vent 26 is formed at the bottom of each recess 27. That is, the air vents 26 are in communication with the recesses 27. The opening area of ​​each recess 27 on the lower surface 24 is larger than the opening area of ​​the air vents 26 on the upper surface 23.

[0024] On the base 2, a mounting leg 4 is provided on the longer side of each short side. Each mounting leg 4 is connected to the short side of the base 2. Each mounting leg 4 is the same shape and is used to fix the tap changer base 1 (base 2) to, for example, the ground terminal (not shown) of a core tightening fitting for fixing a wound core.

[0025] As shown in Figures 1 and 2, each mounting leg 4 is a roughly rectangular plate shape with one end bent. More specifically, the other end of each mounting leg 4 is connected to the base 2 and extends diagonally downward in a direction away from the lower surface 24 of the base 2, with one end bent parallel to the base 2. The two mounting legs 4 extend in directions that separate them from each other. That is, each mounting leg 4 has an inclined portion 41 that extends diagonally with respect to the thickness direction of the base 2, below the base 2 and outward, and a parallel portion 42 that is parallel to the base 2.

[0026] Each mounting leg 4 is made of a thermoplastic resin, which has heat resistance, oil resistance, and electrical insulation properties. Specifically, the mounting legs 4, like the base 2, are made of a thermoplastic resin such as polyamide resin or PPS (polyphenylene sulfide) resin, and are integrally formed with the base 2.

[0027] The mounting leg portion 4 is also provided with reinforcing ribs 44 along its edge. The reinforcing ribs 44 protrude in the thickness direction of the mounting leg portion 4 and are connected to the reinforcing ribs 21 of the base portion 2. In addition, a boss 43 is provided in the center of the parallel portion 42, which is used when attaching the tap changer base 1 to the ground terminal of the iron core tightening fitting. The tap changer base 1 is fixed by inserting a bolt (not shown) into the boss 43 and screwing it to the ground terminal.

[0028] As described above, in the tap changer stand 1 according to this embodiment, a plurality of air vents 26 are formed between the two mounting seats 22 rows. Therefore, even if air adheres to the lower surface 24 of the base portion 2 of the tap changer stand 1 when insulating oil is applied during the manufacturing of the oil-filled transformer, the adhered air can be released through the air vents 26 in the subsequent degassing process. Thus, it is possible to prevent air from accumulating on the lower surface 24 of the base portion 2 and to prevent short circuits from occurring between the tap terminals 3 via such air.

[0029] Furthermore, in the tap switching stand 1 according to this embodiment, air vents 26 are formed corresponding to each mounting seat 22 (tap terminal 3), and each air vent 26 has the shape of an identification symbol that identifies the corresponding mounting seat 22 (tap terminal 3). Therefore, during tap switching operations, the identifiability of the tap terminal 3 to be worked on is improved, allowing for safe and accurate tap switching operations. Furthermore, since the air vent hole 26 itself also serves as an identification symbol for the tap terminal 3, there is no need to provide a separate identification symbol.

[0030] Furthermore, in the tap switching stand 1 according to this embodiment, recesses 27 are provided on the lower surface 24 of the base portion 2, and the opening area of ​​each recess 27 on the lower surface 24 is larger than the opening area of ​​the air vent holes 26 on the upper surface 23. Therefore, if air accumulates on the lower surface 24 of the base portion 2, it is quickly collected by the recess 27 and guided to the air vent hole 26.

[0031] Furthermore, in the tap switching stand 1 according to this embodiment, the mounting leg portion 4 is made of a thermoplastic resin with excellent insulating properties, which improves the electrical insulation between the ground terminal of the iron core tightening fitting and the tap terminal 3.

[0032] Furthermore, in the tap switching stand 1 according to this embodiment, the mounting legs 4 (inclined portion 41) are provided at an angle to the base 2, so the creepage distance between the ground terminal and the tap terminal 3 can be increased compared to when they are provided vertically, and the electrical insulation can be further improved.

[0033] The above explanation uses the example of the air vents 26 being shaped like numbers, but it is not limited to this. For example, the shapes of each air vent 26 may be holes of different sizes, or they may be the same shape but facing different directions.

[0034] Furthermore, although the above explanation uses the example of six air vents 26, it is not limited to this, and the number of air vents 26 may be less than six or seven or more.

[0035] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims, not in the sense described above, and all modifications are intended to be in the sense and scope equivalent to the claims.

[0036] The matters described in each embodiment can be combined with each other. Furthermore, the independent and dependent claims described in the claims can be combined with each other in any combination, regardless of the form of reference. In addition, the claims use a form in which claims referencing two or more other claims (multi-claim form), but are not limited to this. A form in which multi-claims referencing at least one multi-claim (multi-multi-claim) may also be used. [Explanation of symbols]

[0037] 1: Tap changer base, 2: Base, 3: Tap terminal, 22: Mounting base, 23: Top surface, 24: Bottom surface, 26: Air vent, 27: Recess

Claims

1. A tap changer used in a transformer that stores insulating oil internally, It has a base with multiple mounting seats for tap terminals, The base portion of the tap changer has at least one air vent hole formed in the center between the mounting seats.

2. The aforementioned multiple mounting bases are arranged in two rows, The tap switching stand according to claim 1, wherein the air vents are formed between the two rows.

3. The tap switching stand according to claim 1 or 2, wherein the air vents are plurality and provided corresponding to each mounting seat.

4. The tap switching stand according to claim 3, wherein each air vent is shaped like an identification symbol that identifies the corresponding mounting seat.

5. On the lower surface of the base, recesses that open downwards are formed at positions corresponding to each air vent. The tap switching stand according to claim 4, wherein the air vent hole is in communication with the recess.

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