Gasket

Abstract

To provide a gasket which can be removed from a primary bushing and replaced easily and safely in a short time.SOLUTION: In a gasket 1a, a portion of a circular nitrile rubber plate material 2 is cut along a slit 3, and a double-sided tape 4, which has a base material coated with a rubber adhesive or pressure-sensitive adhesive on both sides, is affixed to a cut surface 2a formed by the slit 3. The gasket 1b is composed of a pair of plates 2, 2 with the double-sided tape 4 affixed to a side surfaces 2b.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gasket used in the primary bushing of a transformer (pole-mounted transformer) installed on a utility pole, and in particular to a gasket that can be removed from the primary bushing and replaced easily and safely in a short time. [Background technology]

[0002] Gaskets are attached to the primary bushings of pole-mounted transformers to increase the airtightness of the transformer body and prevent leakage of insulating oil and the intrusion of rainwater from the outside. It is known that when flying chlorides and dust accumulate on the primary bushing, creeping discharges occur repeatedly between the primary bushing and the case, and the resulting heat can burn the gasket. If the gasket burns and the airtightness of the transformer body decreases, there is a risk that the transformer body will be burned due to leakage of vaporized insulating oil or the intrusion of rainwater from the outside. To prevent such situations, the gasket material has now been changed from cork synthetic rubber to nitrile rubber, but the need to replace the gasket periodically remains.

[0003] The structure of the primary bushing of the pole transformer will now be explained with reference to Figures 5 and 6. Figures 5(a) and 5(b) are a front view of pole transformer 50 and a side view of primary bushing 53, respectively. Also, Figure 6(a) is a cross-sectional view showing part of the internal structure of pole transformer 50, and Figures 6(b) and 6(c) are plan views of mounting bracket 68 and gasket 67, respectively. In Figure 6(a), the annular recess 58a of the primary bushing 53 is not shown, and the hatching indicating that the outer box body 51 and upper cover 52 of the pole transformer 50 are cross-sectional is not shown.

[0004] As shown in Figure 5(a), the pole-mounted transformer 50 comprises a high-voltage winding molded with a resin such as epoxy, a low-voltage winding placed inside the high-voltage winding, an iron core around which these windings are placed, an outer box body 51 formed from a synthetic resin such as metal or glass fiber reinforced resin, an upper cover 52 attached to the top of the outer box body 51, and a pair of primary bushings 53, 53 and a secondary bushing 54 provided on a side 51a of the outer box body 51, and a pair of upper hanger seats 55, 55 and a pair of lower hanger seats 56, 56 are installed at the top and bottom of the side 51a of the outer box body 51 symmetrically with the secondary bushing 54 between them and so that they are positioned in the same position when viewed circumferentially around the side 51a of the outer box body 51. 5(b), the primary bushing 53 is made of hard porcelain and comprises a small-diameter portion 57 with spring grooves 57a formed on its outer periphery and a large-diameter portion 58 with multiple annular recesses 58a formed on its outer periphery, through which a center conductor (not shown) is inserted. A terminal metal fitting cover 59, also made of hard porcelain, is attached to the tip of the large-diameter portion 58.

[0005] 6(a) to 6(c), a lead wire 60 is connected to the above-mentioned center conductor of the primary bushing 53 via a terminal metal fitting cover 59, and a terminal block 62 is installed inside the pole transformer 50 while immersed in insulating oil 61. The terminal block 62 is connected to one end of a terminal wire 65, which is made of soft copper electrical wire and partially covered with a paper tube 63 or an insulating tube 64 made of polyester film, and the other end of the terminal wire 65 is connected to the center conductor. A primary bushing mounting pocket 66 is provided in the outer casing body 51 of the pole transformer 50, and a bushing hole (not shown) provided in a bottom plate 66a of the primary bushing mounting pocket 66 has an insertion hole 67a, into which the small diameter portion 57 of the primary bushing 53 is inserted with an insertion hole 67a fitted with a circular nitrile rubber gasket 67 made of a plate material. Furthermore, a metal mounting bracket 68 having an annular shape is fitted onto the small diameter portion 57 of the primary bushing 53 arranged inside the primary bushing mounting pocket 66 .

[0006] The mounting bracket 68 has three annular receiving portions 68b, each having an arc-shaped cross section, which are provided around the periphery of the insertion hole 68a so as to bulge outward, and a screw hole 68c is provided between each two adjacent annular receiving portions 68b, 68b. The small diameter portion 57 of the primary bushing 53 is fixed to the bottom plate 66a of the primary bushing mounting pocket 66 by threading a screw 70 into the screw hole 68c of the mounting bracket 68 with a coil spring 69 fitted in the spring groove 57a.

[0007] Next, the replacement work of the gasket 67 will be explained with reference to Fig. 7. Fig. 7 is a flowchart showing the work procedure when replacing the conventional gasket 67. As shown in Fig. 7, first, after taking measures to prevent scattering and adhesion of insulating oil 61, the terminal wire 65 is removed from the terminal block 62 (steps S1 and S2). Next, the screws 70 of the mounting bracket 68 are loosened to remove the coil spring 69 from the spring groove 57a of the small diameter portion 57 of the primary bushing 53, and the mounting bracket 68 is removed from the small diameter portion 57 of the primary bushing 53 (steps S3 to S5). Then, the small diameter portion 57 of the primary bushing 53 is removed from the bushing hole provided in the bottom plate 66a of the primary bushing mounting pocket 66, and the gasket 67 is removed from the small diameter portion 57 of the primary bushing 53 (step S6). Then, the area around the bushing hole in the bottom plate 66a of the primary bushing mounting pocket 66 is cleaned (step S7).

[0008] Next, the small diameter portion 57 of the primary bushing 53 with the new gasket 67 fitted thereto is inserted into a bushing hole provided in the bottom plate 66a of the primary bushing mounting pocket 66, and then the mounting bracket 68 is attached to the small diameter portion 57 (steps S8 and S9). Furthermore, the coil spring 69 is fitted into the spring groove 57a of the small diameter portion 57, and the screw 70 threaded into the screw hole 68c of the mounting bracket 68 is tightened to fix the primary bushing 53 to the bottom plate 66a of the primary bushing mounting pocket 66 (steps S10 and S11). Thereafter, the terminal wire 65 is connected to the terminal block 62 (step S12). As described above, when removing and replacing the conventional gasket 67 from the primary bushing 53, it is necessary to remove the terminal wire 65 from the terminal block 62, which is immersed in the insulating oil 61. This requires work to prevent the insulating oil 61 from scattering or adhering to the worker, and it takes a lot of time and effort to replace the gasket 67. In addition, when removing the primary bushing 53 from the pole transformer 50, there is a risk that small parts used to secure the primary bushing 53 to the outer box body 51 may fall into the insulating oil 61, making it difficult to retrieve them.

[0009] Regarding gaskets attached to the primary bushings of pole-mounted transformers, for example, Patent Document 1 discloses an invention entitled "Gasket supplementary packing for pole-mounted transformer primary bushing," which relates to packing that prevents insulating oil from leaking from mounting holes when replacing pole-mounted transformers, etc. Using the symbols shown in the drawings of Patent Document 1, Patent Document 1 describes an elastic frame 1 made of flame-retardant ACS resin, an annular body divided in the front-to-rear direction at one location on the outer periphery, a sealing material 2 made of closed-cell synthetic rubber, an annular body divided in the front-to-rear direction at one location on the outer periphery and attached by bonding to the inner circumferential surface 7 at one end of the elastic frame 1, and a gasket auxiliary packing A having a structure equipped with an insulation lock mechanism 3 attached to the elastic frame 1 as a fastening means, as well as a donut-shaped plate-shaped gasket 29 made of cork material that is fitted into the base end side portion 23a of the insulator body 23. With this structure, even if a crack occurs in the gasket 29, insulating oil leaking from the mounting hole of the primary bushing when the transformer is tilted during movement or replacement work is trapped inside the sealing material 2, so there is no risk of it scattering around. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-12723 Summary of the Invention [Problem to be solved by the invention]

[0011] In the invention disclosed in Patent Document 1, even if the transformer is tilted with a crack in the gasket 29, there is no risk of insulating oil leaking from the mounting hole of the primary bushing scattering around. However, because the gasket 29 is donut-shaped, when replacing it, the terminal wires must be removed from the terminal block, which is immersed in the insulating oil, which makes the replacement process time-consuming.

[0012] The present invention has been made in response to the above-mentioned conventional circumstances, and aims to provide a gasket that can be removed from a primary bushing and replaced easily and safely in a short time. [Means for solving the problem]

[0013] In order to achieve the above object, the first invention is a gasket in which a primary bushing of a pole-mounted transformer is placed, characterized in that it comprises at least one plate-shaped elastic member having a shape in which part of the annular ring is cut by a notch. In the first invention, the elastic member is deformed so that the pair of cut surfaces formed by the notches are shifted horizontally relative to each other, and when the distance between the pair of cut surfaces becomes wider than the outer diameter of the primary bushing, the primary bushing can be positioned inside the elastic member from between the pair of cut surfaces.

[0014] A second invention is characterized in that, in the first invention, the pair of elastic members have adhesive or pressure-sensitive adhesive layers formed on their side surfaces. In the second invention, when a pair of elastic members are installed on the primary bushing so that the pair of notches do not overlap when viewed in the direction of the central axis of the ring and so that their central axes are aligned, the side surfaces of the pair of cut surfaces in one elastic member are connected via the side surfaces of the other elastic member, which has the effect of increasing the airtightness of the elastic members in addition to the effect of the first invention.

[0015] The third invention is characterized in that, in the second invention, the sides of a pair of elastic members are connected together over a range not exceeding halfway around the circumference, except for the areas where the notches are provided. In the third invention, the side surfaces of a pair of elastic members are connected over a range not exceeding half the circumference, except for the areas where the notches are provided, which has the effect of making the elastic members more airtight than in the second invention, in which the side surfaces are bonded or adhered together when attached to the primary bushing.

[0016] The fourth invention is characterized in that, in the second or third invention, a double-sided tape having a rubber adhesive or pressure-sensitive adhesive applied to both sides of a base material is attached to the side of the elastic member. In the fourth invention, in addition to the effects of the second or third invention, the double-sided tape has the effect of easily forming an adhesive or pressure-sensitive adhesive layer on the side surfaces of a pair of elastic members. Furthermore, if the release paper is left on the side of the double-sided tape base that is not in contact with the elastic members without being peeled off, the release paper prevents the part to which the double-sided tape is attached from adhering or sticking to the part in contact with it before use.

[0017] A fifth invention is characterized in that, in the first invention, the elastic member has an adhesive layer or a pressure-sensitive adhesive layer formed on the cut surface formed by the slit. In the fifth invention, when attached to the primary bushing, the pair of cut surfaces formed by the notch are bonded or adhered to each other, which has the effect of increasing the airtightness of the elastic member compared to the first invention. [Effects of the Invention]

[0018] In the first invention, because the primary bushing can be attached or detached from the side, there is no need to remove the terminal wires connected to the terminal block immersed in insulating oil before removing the primary bushing from the outer casing of the pole transformer during replacement. This eliminates the need for work to prevent insulating oil from splashing or adhering to workers, and also prevents small parts used to secure the primary bushing to the outer casing from falling into the insulating oil when removing the primary bushing, making it difficult to recover them. Therefore, according to the first aspect of the present invention, the work of removing the primary bushing and replacing it can be carried out easily and safely in a short time.

[0019] According to the second invention, in addition to the effect of the first invention, the airtightness is high when attached to the primary bushing, and therefore the effect of high safety during use is achieved.

[0020] According to the third invention, the airtightness when attached to the primary bushing is higher than in the case of the second invention, so the effect of the second invention, which is excellent safety during use, is further exerted.

[0021] According to the fourth invention, since the adhesive or pressure-sensitive adhesive layer can be easily formed on the side surfaces of the pair of elastic members using the double-sided tape, in addition to the effects of the second or third invention, the fourth invention has the effect of reducing manufacturing costs. Also, in the fourth invention, if the release paper on the side of the base material of the double-sided tape that is not in contact with the elastic member is left unpeeled, the part to which the double-sided tape is attached and the part in contact with it will not be adhered or stuck together before use, making it easy to handle when carrying or storing.

[0022] According to the fifth aspect of the invention, the airtightness of the elastic member when attached to the primary bushing is higher than that of the first aspect of the invention, which provides the effect of excellent safety during use. [Brief explanation of the drawings]

[0023] [Figure 1]FIG. 1(a) is a perspective view showing the appearance of Example 1 of a gasket according to an embodiment of the present invention, FIG. 1(b) is a view showing a state in which a part of the gasket in FIG. 1(a) has been deformed, and FIG. 1(c) and FIG. 1(d) are a side view of a modified example of the gasket of Example 1 and a view for explaining its structure, respectively. [Figure 2] 10 is a flowchart showing the procedure for replacing the gasket of the present invention. [Figure 3] 10(a) to 10(c) show the gasket being removed from the primary bushing. [Figure 4] (a) and (b) are respectively an oblique view and a side view showing the appearance of Example 2 of a gasket according to an embodiment of the present invention, (c) is a view showing the state in which the gasket in (a) has been deformed, and (d) is a cross-sectional view taken along line AA in (a). [Figure 5] (a) and (b) are a front view of the pole transformer and a side view of the primary bushing, respectively. [Figure 6] (a) is a cross-sectional view showing part of the internal structure of a pole-mounted transformer, and (b) and (c) are plan views of the mounting bracket and gasket, respectively. [Figure 7] 10 is a flowchart showing a procedure for replacing a conventional gasket. DETAILED DESCRIPTION OF THE INVENTION

[0024] The structure, function and effect of a gasket according to an embodiment of the present invention will be specifically described with reference to FIGS. [Example]

[0025] FIG. 1(a) is a perspective view showing the appearance of a gasket 1a according to an embodiment of the present invention, FIG. 1(b) is a view showing the state in which the gasket 1a in FIG. 1(a) has been deformed, and FIG. 1(c) and FIG. 1(d) are side views of a gasket 1b corresponding to a modified version of the gasket 1a and views for explaining its structure. The components already described with reference to FIGS. 5 and 6 are denoted by the same reference numerals and will not be described again.

[0026] As shown in Figures 1(a) and 1(b), the gasket 1a of the present invention has an insertion hole 2c through which a small diameter portion 57 of a primary bushing 53 of a pole transformer 50 is inserted, and a portion of a circular nitrile rubber plate material 2 is cut by a slit 3, and double-sided tape 4, which has a base material coated with a rubber adhesive or pressure-sensitive adhesive on both sides, is attached to the cut surface 2a formed by this slit 3. 1(b), the gasket 1a can be deformed so that the pair of cut surfaces 2a, 2a formed by the slits 3 are laterally shifted from each other. When the plate material 2 is deformed so that the distance between the pair of cut surfaces 2a, 2a is wider than the outer diameter of the small diameter portion 57 of the primary bushing 53, it becomes possible to position the small diameter portion 57 of the primary bushing 53 inside the plate material 2 between the pair of cut surfaces 2a, 2a.

[0027] As shown in FIGS. 1(c) and 1(d), the gasket 1b is made up of a pair of plate materials 2, 2 with double-sided tape 4 attached to the side surfaces 2b. Therefore, when a pair of plate materials 2, 2 are attached to the small diameter portion 57 of the primary bushing 53 so that the pair of notches 3, 3 do not overlap when viewed in the direction of the central axis of the annulus and so that their central axes are aligned, the side surfaces 2b of the pair of cut surfaces 2a, 2a of one plate material 2 are connected via the side surface 2b of the other plate material 2. In this case, the airtightness is higher than in the case of a single plate material 2 such as gasket 1a, in which the pair of cut surfaces 2a, 2a are connected with double-sided tape 4, and therefore gasket 1b is safer in use than when a single plate material 2 is used.

[0028] In gasket 1b, the side surfaces 2b of the pair of plate materials 2, 2 are not bonded or adhered to each other and remain independent until they are attached to primary bushing 53, so the same effect as that of gasket 1a is exhibited in gasket 1b. That is, in gasket 1b, by deforming the pair of plate materials 2, 2 so that the distance between the pair of cut surfaces 2a, 2a is wider than the outer diameter of small diameter portion 57 of primary bushing 53, it becomes possible to place small diameter portion 57 of primary bushing 53 inside the two plate materials 2.

[0029] Here, the replacement work of the gasket 1a will be explained using Figures 2 and 3. Figure 2 is a flowchart showing the procedure for replacing the gasket 1a, and Figures 3(a) to 3(c) are diagrams showing how the gasket 1a is removed from the primary bushing 53 (see Figure 6(a)). First, in the primary bushing 53 shown in Fig. 3(a), the screw 70 of the mounting bracket 68 is loosened and retracted from the bottom plate 66a of the outer box body 51 as shown in Fig. 3(b). This allows the primary bushing 53 to be pulled out of the bushing hole in the bottom plate 66a by the amount that the screw 70 is retracted (step S1 in Fig. 2). Then, when the primary bushing 53 is pulled out of the bushing hole until the mounting bracket 68 abuts against the outer box body 51 of the pole transformer 50, the side surface 2b of the gasket 1a is separated from the bottom plate 66a as shown in Fig. 3(c). Then, the pair of cut surfaces 2a, 2a of the gasket 1a are deformed by shifting them laterally so that the distance between the pair of cut surfaces 2a, 2a is wider than the outer diameter of the small-diameter portion 57 of the primary bushing 53, and the gasket 1a is removed from the small-diameter portion 57 of the primary bushing 53 (step S2 in Fig. 2).

[0030] In the gasket 1a attached to the small diameter portion 57 of the primary bushing 53, the pair of cut surfaces 2a, 2a are bonded or adhered via the double-sided tape 4, so that the pair of cut surfaces 2a, 2a can be easily separated by applying a force that deforms the plate material 2. Even if the adhesive or cohesive force between the pair of end surfaces 2a, 2a is strong and they cannot be easily separated, the gasket 1a can be removed from the small diameter portion 57 of the primary bushing 53 by cutting the plate material 2 with a tool or blade. Note that, because the gasket 1a is disposed on the outside of the housing body 51 of the pole transformer 50 as shown in FIG. 3(c), the above-mentioned operation of cutting the plate material 2 can be performed extremely easily.

[0031] After removing the gasket 1a from the small diameter portion 57 of the primary bushing 53, the area around the bushing hole in the bottom plate 66a of the primary bushing attachment pocket 66 is cleaned (step S2 in FIG. 2). Then, a new gasket 1a is attached to the small diameter portion 57 of the primary bushing 53 by reversing the procedure used to remove the gasket 1a from the small diameter portion 57 of the primary bushing 53 in step S2, and the primary bushing 53 is fixed to the bottom plate 66a of the primary bushing attachment pocket 66 by tightening the screw 70 threaded into the screw hole 68c of the mounting bracket 68 (steps S4 and S5 in FIG. 2).

[0032] Because gasket 1a can be attached to and detached from small-diameter portion 57 of primary bushing 53 from the side, when replacing it, there is no need to remove terminal wire 65 from terminal block 62 immersed in insulating oil 61 and then remove primary bushing 53 from outer box body 51 of pole transformer 50, as shown in FIG. 6(a). In this case, no work is required to prevent insulating oil 61 from scattering or adhering to the worker, and when removing primary bushing 53, small parts used to secure primary bushing 53 to outer box body 51 do not fall into insulating oil 61, making recovery difficult. Therefore, using gasket 1a makes it possible to remove and replace primary bushing 53 easily and safely in a short time.

[0033] As described above, replacing the gasket 1a requires the steps S1 to S5 shown in Fig. 2, whereas replacing the conventional gasket 67 requires the steps S1 to S12 shown in Fig. 7. In other words, when the gasket 1a is used for the primary bushing 53 of the pole transformer 50, the amount of work that needs to be done is significantly less than when the conventional gasket 67 is used, and therefore the time required for replacement can be significantly reduced. Incidentally, since gasket 1b can also be attached to and detached from small diameter portion 57 of primary bushing 53 from the side, the same functions and effects as those of gasket 1a are also exerted in gasket 1b.

[0034] In the first embodiment of the present invention, as shown in Fig. 1(b), the double-sided tape 4 is attached to one of the pair of cut surfaces 2a, 2a, but the double-sided tape 4 may also be attached to the other cut surface 2a. Also, Fig. 1(d) shows the double-sided tape 4 attached to one of the pair of side surfaces 2b, 2b, but this is not limiting, and the double-sided tape 4 may also be attached to the other side surface 2b. [Example]

[0035] Figures 4(a) and 4(b) are a perspective view and a side view, respectively, showing the appearance of gasket 1c of the present invention, Figure 4(c) is a view showing the gasket 1c in Figure 4(a) in a deformed state, and Figure 4(d) is a cross-sectional view taken along line AA in Figure 4(a). Note that components already explained using Figures 5 and 6 are given the same reference numerals and their explanation will be omitted. 4(a) to 4(d), a gasket 1c of the present invention has an insertion hole 5f through which a small-diameter portion 57 of a primary bushing 53 of a pole transformer 50 is inserted, and a first slit 6a perpendicular to the central axis of the ring is provided on a part of the outer peripheral surface 5a of an annular nitrile rubber plate 5 so as to reach the inner peripheral surface 5b, and a pair of second slits 6b, 6b parallel to the central axis of the ring are provided on a pair of side surfaces 5g, 5g so as to reach both ends of the first slit 6a. In addition, a double-sided tape 4 is attached to a cut surface 5c formed by the first slit 6a, and of cut surfaces 5d, 5e formed by the second slit 6b, a double-sided tape 4 is attached to the cut surface 5d.

[0036] That is, gasket 1c has a structure equivalent to that of gasket 1b, in which the side surfaces 2b, 2b of a pair of plate materials 2, 2 are connected together over half the circumference, excluding the area where notch 3 is provided. Therefore, gasket 1c has higher airtightness than gasket 1b, in which the side surfaces 2b, 2b of a pair of plate materials 2, 2 are bonded or adhered together when attached to primary bushing 53. Therefore, gasket 1c is safer in use than gasket 1b.

[0037] As shown in FIG. 4(c), gasket 1c can be deformed so that cut surfaces 5d and 5e are laterally offset from each other. When plate 5 is deformed so that the distance between cut surfaces 5d and 5e is wider than the outer diameter of small-diameter portion 57 of primary bushing 53, small-diameter portion 57 of primary bushing 53 can be positioned inside plate 5 between cut surfaces 5d and 5e. Therefore, gasket 1c can also be attached to and detached from small-diameter portion 57 of primary bushing 53 from the side. In this case, when replacing the primary bushing 53, there is no need to remove terminal wires 65 from terminal block 62 immersed in insulating oil 61 and then remove primary bushing 53 from outer box body 51 of pole transformer 50. This eliminates the need to perform procedures to prevent insulating oil 61 from splashing or adhering to the worker. Furthermore, when removing primary bushing 53, small parts used to secure primary bushing 53 to outer box body 51 do not fall into insulating oil 61, making them difficult to retrieve. Therefore, the gasket 1c can also be removed from the primary bushing 53 and replaced easily and safely in a short time. As with the gaskets 1a and 1b, the gasket 1c also has the effect of significantly reducing the time required for replacement.

[0038] As described above, gasket 1c corresponds to the structure of gasket 1b in which the side surfaces 2b, 2b of a pair of plate materials 2, 2 are connected over half the circumference, excluding the area where slit 3 is provided. However, the range over which the side surfaces 2b, 2b of the pair of plate materials 2, 2 are connected is not limited to half the circumference and can be modified as appropriate. However, if the range exceeds half the circumference, it becomes difficult to deform plate material 5 so that the distance between cut surfaces 5d, 5e is wider than the outer diameter of small-diameter portion 57 of primary bushing 53. Therefore, it is desirable that the range does not exceed half the circumference. Also, although double-sided tape 4 is attached to cut surface 5c formed by first slit 6a over half the circumference, the range over which double-sided tape 4 is attached is not limited to this and can be modified as appropriate. However, since it becomes difficult to deform the cut surfaces 5d and 5e so as to shift them laterally relative to each other in order to position the small diameter portion 57 of the primary bushing 53 between the cut surfaces 5d and 5e inside the plate material 5, it is desirable that the range does not exceed half the circumference.

[0039] Furthermore, although double-sided tape 4 is used for gaskets 1a to 1c, it is also possible to apply an adhesive or pressure-sensitive adhesive to the locations where an adhesive layer or sticky layer is to be formed without using double-sided tape 4. However, using double-sided tape 4 has the advantage of reducing manufacturing costs compared to applying an adhesive or sticky layer, since the adhesive layer or sticky layer can be easily formed. Furthermore, if the release paper on the side of the base material of the double-sided tape 4 that is not in contact with the plate materials 2 and 5 is left unpeeled, the release paper prevents the part to which the double-sided tape 4 is attached from adhering or sticking to the part in contact with it before use, making it easy to handle when transporting or storing.

[0040] In the second embodiment of the present invention, as shown in Fig. 4(c), the double-sided tape 4 is attached only to the cut surface 5d formed by the second slit 6b, but the double-sided tape 4 may also be attached to the cut surface 5e. Also, Fig. 4(d) shows a state in which the double-sided tape 4 is attached to one of the pair of cut surfaces 5c, 5c, but the double-sided tape 4 may also be attached to the other cut surface 5c.

[0041] Furthermore, the gaskets 1a to 1c in the first and second embodiments of the present invention may use, as the plate material 2 and the plate material 5, elastic members made of rubber other than nitrile rubber. [Industrial Applicability]

[0042] The present invention is applicable to the primary bushing of a pole-mounted transformer. [Explanation of symbols]

[0043] 1a to 1c...Gasket 2...Plate (elastic member) 2a...Cut surface 2b...Side surface 2c...Insertion hole 3...Slit 4...Double-sided tape 5...Plate 5a...Outer surface 5b...Inner surface 5c to 5e...Cut surface 5f...Insertion hole 5g...Side surface 6a...First notch 6b...Second notch 50...Pole-mounted transformer 51...Outer box body 51a...Side surface 52...Top cover 53...Primary bushing 54...Secondary bushing 55...Upper hanger seat 56...Lower hanger seat 57...Small diameter portion 57a...Spring groove 58...Large diameter portion 58a...Annular recess 59...Terminal metal fitting cover 60...Lead wire 61...Insulating oil 62...Terminal block 63...Paper tube 64...Insulating tube 65...Terminal wire 66...Primary bushing mounting pocket 66a... Bottom plate 67... Gasket 67a... Insertion hole 68... Mounting bracket 68a... Insertion hole 68b... Annular receiving portion 68c... Screw hole 69... Coil spring 70... Screw

Claims

1. A gasket in which a primary bushing of a pole transformer is placed, A gasket comprising at least one plate-like elastic member having a ring shape with a portion thereof cut by a slit.

2. 2. The gasket according to claim 1, comprising a pair of elastic members each having an adhesive layer or a pressure-sensitive adhesive layer formed on its side surface.

3. 3. The gasket according to claim 2, wherein the side surfaces of the pair of elastic members are connected together over a range not exceeding halfway around the circumference, excluding the portions where the notches are provided.

4. 4. The gasket according to claim 2, wherein a double-sided tape having a base material coated on both sides with a rubber adhesive or pressure-sensitive adhesive is attached to the side surface of the elastic member.

5. 2. The gasket according to claim 1, wherein the elastic member has an adhesive layer or a pressure-sensitive adhesive layer formed on the cut surface formed by the cut.

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