JP7651360B2 - Lightning arrester - Google Patents

Description

An embodiment of the present invention relates to a lightning arrester.

A lightning arrester is used to protect electric power equipment and the like from high voltages. A lightning arrester includes, for example, a nonlinear resistor, an electrode, an insulating rod, and an outer casing. The electrodes are provided at both ends of the nonlinear resistor. The insulating rod connects the electrodes together. The outer casing covers the internal elements (nonlinear resistor, electrode, insulating rod, etc.). The electrode has an insertion hole. The insertion hole has an inclined inner circumferential surface. The insulating rod and the electrode are fixed by pressing a wedge-shaped spacer into the insertion hole. To ensure the mechanical strength of the lightning arrester, it is desirable for the fixing structure between the insulating rod and the electrode to have high strength.

The above-mentioned lightning arrester was not easy to assemble because the fixing structure between the insulating rod and the electrode was complex. The above-mentioned lightning arrester had a complex structure, so it was difficult to reduce the manufacturing cost.

JP 2013-229362 A JP 2014-22632 A

The problem that this invention aims to solve is to provide a lightning arrester that has sufficient mechanical strength and is simple in structure.

The lightning arrester of the embodiment has a non-linear resistor, an electrode, and one or more insulating plates. The electrodes are provided at one end and the other end of the non-linear resistor. The insulating plate connects the electrode provided at one end of the non-linear resistor to the electrode provided at the other end of the non-linear resistor. A protrusion is formed on the side of the electrode. The insulating plate is formed with a fitting hole into which the protrusion fits.

FIG. 2 is a cross-sectional view showing the lightning arrester of the first embodiment. FIG. 2 is a plan view showing the lightning arrester of the first embodiment. FIG. 2 is a cross-sectional view showing a portion of the lightning arrester according to the first embodiment. FIG. 2 is a side view showing the internal structure of the lightning arrester of the first embodiment. FIG. 6 is a plan view showing a lightning arrester according to a second embodiment. FIG. 6 is a cross-sectional view showing a portion of a lightning arrester according to a second embodiment. FIG. 13 is a cross-sectional view showing a lightning arrester according to a third embodiment. FIG. 2 is a diagram showing a part of the AA cross section of the previous figure.

The lightning arrester of the embodiment will be described below with reference to the drawings.

(First embodiment)
Fig. 1 is a cross-sectional view showing a lightning arrester 100 of a first embodiment. Fig. 2 is a plan view showing the lightning arrester 100. Fig. 3 is a cross-sectional view showing a part of the lightning arrester 100. Fig. 4 is a side view showing the internal structure of the lightning arrester 100.

In the following explanation, the positional relationship of the lightning arrester 100 will be provisionally defined based on FIG. 1. As shown in FIG. 1, multiple non-linear resistors 1 are stacked in the vertical direction. The non-linear resistor group 20 extends in the vertical direction. A view from the vertical direction is called a plan view.

As shown in FIG. 1, the lightning arrester 100 includes a plurality of nonlinear resistors 1, a pair of spacers 2, a pair of electrodes 3, a pair of fixing devices 4, a plurality of insulating plates 5, a pair of retaining plates 7, and an outer sheath 10.

The nonlinear resistor 1 is an element having a nonlinear voltage/current characteristic in which the resistance decreases as the voltage increases. The nonlinear resistor 1 is mainly composed of zinc oxide, for example. The nonlinear resistor 1 is formed, for example, in a disk or cylindrical shape. Multiple nonlinear resistors 1 are stacked in the thickness direction (central axis direction) to form a nonlinear resistor group 20.

The spacers 2 are provided at the upper end (one end) and lower end (the other end) of the non-linear resistor group 20. The spacer 2 provided at the upper end (one end) of the non-linear resistor group 20 is a first spacer 2A. The spacer 2 provided at the lower end (the other end) of the non-linear resistor group 20 is a second spacer 2B. The spacer 2 is arranged coaxially with the non-linear resistor group 20. The spacer 2 is made of a conductor such as a metal.

The spacer 2 comprises a spacer body 11 and a cylindrical portion 12. The spacer body 11 is disk-shaped or cylindrical. The outer diameter of the spacer body 11 may be the same as the outer diameter of the non-linear resistor 1. The cylindrical portion 12 of the first spacer 2A extends upward from the upper surface of the spacer body 11. The cylindrical portion 12 of the second spacer 2B extends downward from the lower surface of the spacer body 11. The space inside the cylindrical portion 12 is the insertion hole 8.

The insertion hole 8 formed in the tubular portion 12 of the first spacer 2A is the first insertion hole 8A. The insertion hole 8 formed in the tubular portion 12 of the second spacer 2B is the second insertion hole 8B. The first insertion hole 8A and the second insertion hole 8B are circular in plan view. A female thread is formed in the inner circumferential surface of the first insertion hole 8A and the second insertion hole 8B in a first helical direction (e.g., left-handed direction).

The electrodes 3 are provided on the first spacer 2A and below the second spacer 2B. The electrode 3 provided on the first spacer 2A is the first electrode 3A. The electrode 3 provided below the second spacer 2B is the second electrode 3B. The electrode 3 is formed, for example, in a rectangular column shape (see FIG. 2). The electrode 3 is arranged coaxially with the nonlinear resistor group 20 and the spacer 2. The electrode 3 has an insertion hole into which the cylindrical portion 12 is inserted. The electrode 3 is formed of a conductor such as a metal. Examples of materials that make up the electrode 3 include aluminum, aluminum alloy, and stainless steel. The electrode 3 may be a casting made by die casting or the like.

2, in this embodiment, the electrode 3 has a hexagonal shape in a plan view. The outer surface of the electrode 3 includes a first side surface 3a, a second side surface 3b, and a third side surface 3c. The side surfaces 3a to 3c are formed flat. In a plan view, the angle between any two of the side surfaces 3a to 3c is approximately 120°.
The shape of the electrode 3 in a plan view is not particularly limited. The shape of the electrode 3 in a plan view may be a triangle formed by a first side surface 3 a, a second side surface 3 b, and a third side surface 3 c. The shape of the electrode 3 in a plan view may be a rectangle, a pentagon, or the like.

One or more protrusions 6 are formed on the outer surface of the electrode 3. In this embodiment, one protrusion 6 is formed on each of the side surfaces 3a to 3c. The protrusions 6 protrude radially outward (away from the central axis of the electrode 3) from the side surfaces 3a to 3c.

As shown in FIG. 4, the protrusion 6 has an elliptical shape when viewed from the protruding direction. The "elliptical shape" is a shape that is composed of two straight lines that are parallel and facing each other, and two curved convex lines (e.g., semicircular, elliptical arc, etc.) that connect the ends of the two straight lines. The protrusion 6 has an elliptical shape having a pair of straight side edges 6a and a pair of curved convex end edges 6b. The protrusion 6 has an elliptical shape whose longitudinal direction (long axis direction) is along the up-down direction. The pair of side edges 6a are parallel to each other and face each other. The pair of end edges 6b are semicircular shapes that are convex in the direction away from each other. The longitudinal dimension of the protrusion 6 is greater than the lateral dimension (width direction). The lateral direction of the protrusion 6 is a direction perpendicular to the longitudinal direction when viewed from the protruding direction of the protrusion 6.

As shown in Figures 2 and 3, the protrusion 6 includes a base portion 13 and a main protrusion portion 14. The main protrusion portion 14 is formed in an oval cylindrical shape. The base portion 13 has a shape that gradually expands in diameter from the main protrusion portion 14 toward the base end. The height dimension of the base portion 13 (the dimension in the protruding direction of the protrusion 6) may be, for example, 5 mm or more. The base portion 13 may have a C-chamfered shape or an R-chamfered shape.
Since the protrusion 6 has the base portion 13 with an expanded diameter, it is possible to suppress stress concentration on the base end portion, and therefore the mechanical strength of the protrusion 6 can be increased.

As shown in FIG. 1, an insertion hole 9 is formed in the center of the electrode 3. The insertion hole 9 is formed penetrating the electrode 3 in the up-down direction. The insertion hole 9 formed in the first electrode 3A is the first insertion hole 9A. The insertion hole 9 formed in the second electrode 3B is the second insertion hole 9B. The first insertion hole 9A and the second insertion hole 9B are circular in plan view. A female thread is formed in the inner circumferential surface of the first insertion hole 9A and the second insertion hole 9B in a second helical direction (e.g., right-handed thread direction). The second helical direction is opposite to the first helical direction.

As shown in FIG. 3, the electrode 3 is formed with a mounting hole 15. The mounting hole 15 is formed to open to the tip surface (protruding end surface) of the protrusion 6. A female thread is formed on the inner peripheral surface of the mounting hole 15.

As shown in FIG. 1, the fixture 4 connects the spacer 2 and the electrode 3. The fixture 4 connecting the first spacer 2A and the first electrode 3A is the first fixture 4A. The fixture 4 connecting the second spacer 2B and the second electrode 3B is the second fixture 4B. Male threads are formed on the outer peripheral surfaces of the upper and lower parts of the fixture 4. The male threads on the upper and lower parts of the fixture 4 are formed in different thread directions (spiral directions). The upper part of the fixture 4 is the length portion that includes the upper end. The lower part of the fixture 4 is the length portion that includes the lower end. The fixture 4 is formed of a conductor such as metal.

The male thread on the bottom of the first fastener 4A fits into the female thread of the first insertion hole 8A of the first spacer 2A. The male thread on the top of the first fastener 4A fits into the female thread of the first insertion hole 9A of the first electrode 3A. The male thread on the top of the second fastener 4B fits into the female thread of the second insertion hole 8B of the second spacer 2B. The male thread on the bottom of the second fastener 4B fits into the female thread of the second insertion hole 9B of the second electrode 3B.

As shown in FIG. 3, a receiving recess 4a may be formed at the upper end of the first fastener 4A and the lower end of the second fastener 4B. The receiving recess 4a is formed, for example, in a hexagonal shape when viewed from the longitudinal direction of the fastener 4. The fastener 4 can be rotated around its axis by fitting a tool such as a torque wrench into the receiving recess 4a and rotating it.

The male threads on the upper and lower parts of the fixing device 4 have different screw formation directions (helical directions). Therefore, by rotating the fixing device 4 around its axis, the spacer 2 can be moved in a direction away from the electrode 3. This allows a compressive load to be applied to the nonlinear resistor 1. This improves the connection characteristics of the nonlinear resistor group 20. This improves the reliability of the lightning arrester 100.

4, the insulating plate 5 is in the form of a rectangular flat plate. The insulating plate 5 may have a rectangular shape extending in the vertical direction. The insulating plate 5 is made of an insulating material such as resin. The insulating plate 5 is preferably made of FRP (fiber reinforced plastic).
1, the insulating plate 5 connects the first electrode 3A and the second electrode 3B. A portion of the insulating plate 5 including an upper end (one end) faces a side surface of the first electrode 3A. A portion of the insulating plate 5 including a lower end (the other end) faces a side surface of the second electrode 3B.

As shown in FIG. 2, three insulating plates 5 are used in this embodiment. The three insulating plates 5 are provided facing the side surfaces 3a to 3c of the electrode 3, respectively. The thickness of the insulating plates 5 is approximately equal to the protruding height of the protrusions 6.

As shown in Fig. 4, the insulating plate 5 has fitting holes 16 into which the protrusions 6 fit. The fitting holes 16 have a shape that allows the protrusions 6 to fit. The fitting holes 16 are formed in a portion including an upper end (one end) of the insulating plate 5 and a portion including the upper end (one end). The fitting holes 16 are formed penetrating the insulating plate 5 from the inner surface to the outer surface of the insulating plate 5.
The fitting hole 16 is not limited to a through hole, but may be a recess formed on the inner surface of the insulating plate 5 .

The fitting hole 16 is elliptical when viewed from the thickness direction of the insulating plate 5. The fitting hole 16 is elliptical with a pair of straight side edges 16a and a pair of curved convex end edges 16b. The fitting hole 16 is elliptical with its longitudinal direction along the up-down direction. The pair of side edges 16a are parallel to and face each other. The pair of end edges 16b are semicircular with convex shapes that move away from each other. The major axis of the fitting hole 16 is approximately the same as the major axis of the protrusion 6, or slightly larger than the major axis of the protrusion 6. The minor axis of the fitting hole 16 is approximately the same as the minor axis of the protrusion 6, or slightly larger than the minor axis of the protrusion 6. The insulating plate 5 can be positioned relative to the electrode 3 by fitting the fitting hole 16 onto the protrusion 6.

As shown in Figures 2 and 3, the pressure plate 7 is, for example, rectangular (rectangular) in shape with its longitudinal direction aligned with the up-down direction. The width (dimension in the short direction) of the pressure plate 7 may be the same as the width of the insulating plate 5. The pressure plate 7 restricts the insulating plate 5 from moving in a direction away from the electrode 3. A part of the pressure plate 7 faces the outer surface of the insulating plate 5. Another part of the pressure plate 7 faces the tip surface of the protrusion 6.

As shown in FIG. 3, the pressing plate 7 is fixed to the electrode 3 by fastening a bolt (fixing device) 17 to the mounting hole 15. The pressing plate 7 is fixed to the electrode 3 while pressing down on the insulating plate 5.

As shown in Figs. 1 and 3, the outer casing 10 is made of a resin such as silicone resin. The outer casing 10 covers the nonlinear resistor 1, the spacer 2, the electrode 3, the insulating plate 5, and the pressing plate 7. The lightning arrester 100 is a polymer type lightning arrester because it has a resin outer casing 10. The lightning arrester 100 is used to protect electric power equipment and the like from high voltage.

In the lightning arrester 100, a protrusion 6 is formed on the side of the electrode 3. The insulating plate 5 has a fitting hole 16 into which the protrusion 6 fits. Since the insulating plate 5 can be positioned on the electrode 3 by fitting the protrusion 6 into the fitting hole 16, stress concentration is unlikely to occur on the insulating plate 5 and the electrode 3. This gives the lightning arrester 100 sufficient mechanical strength. Since the mechanical strength of the positioning structure between the insulating plate 5 and the electrode 3 can be increased, a casting made of an inexpensive material such as aluminum (or an aluminum alloy) can be used as the electrode 3. This also allows for reduced manufacturing costs.

Since the lightning arrester 100 has a structure in which the protrusion 6 fits into the fitting hole 16, the positioning structure between the insulating plate 5 and the electrode 3 can be simplified compared to a case in which a fixing structure using a wedge-shaped spacer is used. Because of the simple structure, the lightning arrester 100 is easy to assemble. Unlike a case in which a fixing structure using a wedge-shaped spacer is used, the lightning arrester 100 does not require the use of special tools.

The insulating plate 5 can be made by cutting a fixed-length plate material into strips. Therefore, the lightning arrester 100 is easier to manufacture than when an insulating rod is used. The lightning arrester 100 can reduce manufacturing costs.

When a bending force is applied to the lightning arrester 100, a force may act on the protrusion 6 and the insulating plate 5 in a direction that causes relative displacement up and down.
The protrusion 6 has an elliptical shape with its longitudinal direction aligned with the vertical direction. This allows the protrusion 6 to have high durability against vertical forces. Therefore, when a force acts on the electrode 3 or the insulating plate 5 in a direction that causes a relative vertical displacement, the electrode 3 and the insulating plate 5 are unlikely to be damaged. The protrusion 6 has a curved edge 6b, so stress is unlikely to concentrate on the edge 6b. Therefore, the electrode 3 and the insulating plate 5 are unlikely to be damaged.

In the lightning arrester 100, the fixing device 4 fits into the insertion hole 8 of the spacer 2. The projection 6 of the electrode 3 fits into the fitting hole 16 of the insulating plate 5. In this way, the components of the lightning arrester 100 are joined by fitting, so when a bending force is applied to the lightning arrester 100, stress is easily dispersed. This makes it possible to make the electrode 3 less likely to be damaged.

1 includes a plurality of non-linear resistors 1, the number of the non-linear resistors may be 1. That is, the number of the non-linear resistors may be one or more (any number equal to or greater than two).
Although the lightning arrester 100 includes three insulating plates 5, there is no particular limitation on the number of insulating plates 5. The number of insulating plates may be any number, for example, three or more.

In the lightning arrester 100, a protrusion 6 is formed on the electrode 3, and a fitting hole 16 is formed on the insulating plate 5, but the configuration of the electrode 3 and the insulating plate 5 is not particularly limited. For example, a protrusion may be formed on the insulating plate, and a fitting hole may be formed on the electrode. That is, in the lightning arrester of the embodiment, a protrusion may be formed on one of the electrode and the insulating plate, and a fitting hole may be formed on the other of the electrode and the insulating plate.

In the lightning arrester 100, the shape of the protrusion 6 is an ellipse, but the shape of the protrusion 6 is not particularly limited. The shape of the protrusion when viewed from the protruding direction may be a circle, an ellipse, a rectangle, etc.

Second Embodiment
FIG. 5 is a plan view showing a lightning arrester 200 of the second embodiment. FIG. 6 is a cross-sectional view showing a part of the lightning arrester 200. As shown in FIG. 5 and FIG. 6, the lightning arrester 200 has a fitting groove 21 formed on the outer surface of the electrode 3, into which the insulating plate 5 and the pressing plate 7 can be fitted. The fitting groove 21 is formed along the vertical direction on the outer surface of the electrode 3. The shape of the fitting groove 21 is, for example, rectangular in plan view. The width of the fitting groove 21 is the same as the width of the insulating plate 5 and the pressing plate 7, or slightly larger than the width of the insulating plate 5 and the pressing plate 7. The depth of the fitting groove 21 may be, for example, the same as the total thickness of the insulating plate 5 and the pressing plate 7. The structure other than the fitting groove 21 may be the same as that of the lightning arrester 100 of the first embodiment.

The lightning arrester 200 has a fitting groove 21 formed on the outer surface of the electrode 3 to accommodate the insulating plate 5 and the pressing plate 7, so that when a bending force is applied, the relative displacement between the electrode 3 and the insulating plate 5 can be suppressed. This makes it possible to reduce the stress generated in the protrusion 6 and the insulating plate 5. This makes it possible to increase the mechanical strength of the lightning arrester 200.

Third Embodiment
Fig. 7 is a plan view showing a lightning arrester 300 of the third embodiment. Fig. 8 is a view showing a part of the A-A cross section of Fig. 7. As shown in Fig. 7, in the lightning arrester 300, a partition plate 31 is provided between adjacent non-linear resistor elements 1. The partition plate 31 only needs to be provided between at least one pair of adjacent non-linear resistor elements 1. The partition plate 31 is formed so as to be able to come into contact with a plurality of insulating plates 5. Therefore, the partition plate 31 can regulate the change in the relative position of the plurality of insulating plates 5. The partition plate 31 can regulate the change in the relative position of the non-linear resistor group 20 and the insulating plate 5. The partition plate 31 is formed of a conductor such as a metal.

The partition plate 31 can suppress changes in the relative positions of the multiple insulating plates 5, and changes in the relative positions of the non-linear resistor group 20 and the insulating plates 5. When the lightning arrester 300 is bent, tensile stress occurs in the length direction of the insulating plates 5 on the outside in the bending direction. Compressive stress occurs in the insulating plates 5 on the inside in the bending direction. In the lightning arrester 300, the partition plate 31 can distribute the stress generated in the insulating plates 5 on the outside in the bending direction to the insulating plates 5 on the inside. This can suppress the concentration of stress. This can increase the mechanical strength of the lightning arrester 300.

As an example, the bending characteristics of the lightning arrester 100 shown in Figure 1 were analyzed. More specifically, the amount of displacement (displacement distance) of the upper end of the lightning arrester 100, whose lower end was fixed, was calculated when a radial (bending) force was applied to the upper end. The results are shown in Table 1. The bending moments applied to the lightning arrester 100 were 1000, 2000, 3000, and 4000 [N·m]. In Table 1, the numbers in parentheses indicate the increase (change) in the amount of displacement compared to before the bending moment was increased.

As a comparative example, a lightning arrester using an insulating rod instead of the insulating plate 5 was subjected to the same analysis of bending characteristics as in the embodiment. The comparative lightning arrester includes a nonlinear resistor, electrodes provided at both ends of the nonlinear resistor, an insulating rod, and an outer sheath. The insulating rod connects the electrodes. An insertion hole having an inclined inner surface is formed in the electrode. The insulating rod and the electrode are fixed by pressing a wedge-shaped spacer into the insertion hole.

As shown in Table 1, in the example, when a relatively high bending moment (2000 to 4000 N·m) was applied, the increase (change) in the amount of displacement was equivalent to that of the comparative example. This result shows that the example exhibits sufficient mechanical strength. The lightning arrester of the example has a simpler structure than the comparative example lightning arrester that uses an insulating rod, making it possible to reduce costs. Therefore, the lightning arrester of the example is superior in terms of economy.

According to at least one of the embodiments described above, a protrusion is formed on the side of the electrode. The insulating plate has a fitting hole into which the protrusion fits. In the lightning arrester of the embodiment, the insulating plate can be positioned on the electrode by fitting the protrusion into the fitting hole, so stress is unlikely to concentrate on the insulating plate and the electrode. This gives the lightning arrester sufficient mechanical strength. Since the lightning arrester of the embodiment has a structure in which the protrusion fits into the fitting hole, the positioning structure for the insulating plate and the electrode can be simplified compared to a case in which a fixing structure using a wedge-shaped spacer is used.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are within the scope of the invention and its equivalents as set forth in the claims, as well as the scope and gist of the invention.

1...non-linear resistor, 3...electrode, 4...fixing device, 5...insulating plate, 6...projection, 13...base, 16...fitting hole, 21...fitting groove, 31...partition plate.

Claims (4)

A nonlinear resistor;
an electrode provided at one end and the other end of the nonlinear resistor;
one or more insulating plates connecting the electrode provided at one end of the non-linear resistor to the electrode provided at the other end of the non-linear resistor;
Equipped with
A protrusion is formed on a side surface of the electrode,
a fitting hole into which the protrusion is fitted is formed in the insulating plate ;
A fitting groove into which the insulating plate fits is formed on a side surface of the electrode .
Lightning arrester. The lightning arrester according to claim 1, wherein the protrusion has an elliptical shape whose longitudinal direction is aligned with the extension direction of the nonlinear resistor. The lightning arrester according to claim 1 or 2, wherein the protrusion has a root portion that expands in diameter toward the base end. A plurality of the nonlinear resistors are provided,
The lightning arrester according to claim 1 , wherein a partition plate is provided between at least one pair of adjacent non-linear resistors.

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