JPH0241135B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention mainly applies to
This relates to a corona prevention nut used in overhead line fitting equipment exceeding 230KV.

(Prior art) In an overhead line fitting device for a power transmission line with a voltage exceeding 230 KV, a connecting fitting 21 is connected to the lower end of a suspension insulator chain suspended from a steel tower cross arm as shown in FIG. A hanging fitting 23 is rotatably connected to the connecting bolt 21 with a connecting bolt 22.
It is considered that a nut 24 is screwed into the connecting bolt 22, and a split pin 25 is inserted into the tip of the connecting bolt 22. However, this is an application of the locking structure of the connecting bolt 22 and nut 24 used in low-voltage overhead wire fittings, and the split pin 25 is
The problem is that the electric field concentrates at sharp points and generates corona, causing anxiety to residents at night, etc., and when corona occurs, it also affects radio waves, causing interference with TVs, radios, etc. There is.

In order to prevent the above-mentioned corona from occurring, since it is structurally impossible for the cotter pin 25 to eliminate sharp corners, the nut 24 should be rounded.
Furthermore, a corona prevention nut has been proposed in which the split pin 25 is housed within the nut 24 to provide a shielding effect and prevent the occurrence of corona. This conventional example will be explained with reference to FIGS. 9 and 10. In this conventional example, a housing groove 24a for the split pin 25 is formed on the head side of the nut 24, and
The entire nut 24 is rounded. However, since this corona prevention nut 24 accommodates the split pin 25 on the head side, it is difficult to wrap around the split pin 25 unless the overall shape of the nut is enlarged, and since it has a special shape, the material cost is high. There is a problem that manufacturing is troublesome.

Further, as shown in FIGS. 11 and 12 as a conventional corona prevention nut, an insertion hole 24b through which a split pin 25 can be inserted is formed in the middle part of the nut 24, and the entire nut 24 is shaped into a substantially hemispherical shape. A formed version is proposed. Since the corona prevention nut 24 also wraps the split pin 25 in the middle of the nut, the hanging metal fitting 2
3 to the tip of the nut 24 increases, and the radius of curvature R of the nut head increases in proportion to this, resulting in a problem in that the nut becomes larger and the manufacturing cost increases.

(Problems to be Solved by the Invention) The present invention attempts to solve the problems existing in the above-mentioned prior art, namely, the problem that the corona prevention nut becomes large and cannot be reduced in cost.

(Means for Solving the Problems) In order to solve the above problems, the present invention takes a means of forming split pin storage grooves by making cuts toward the head side of the nut at positions facing each other from the bottom surface of the nut. It's on.

(Function) With the above means, the present invention allows the cotter pin to be placed as close as possible to the bottom side of the nut, so that the shielding effect of the part where electric field concentration does not occur, that is, the main body of the connecting fitting etc. The cotter pin can be located in the space within the resulting shielded angle, and the overall nut is therefore miniaturized.

(Example) Hereinafter, a first example embodying the present invention will be described based on FIGS. 1 to 4.

Figure 1 shows the entire overhead line system of the power transmission line, with the tower 1
A suspension insulator 3 is suspended via a hanging fitting 2,
A support fitting 6 for a power transmission line 5 is attached to the lower end of the suspension insulator 3 via a hanging fitting 4 as well.

As shown in FIG. 2, a connecting fitting 7 is supported at the lowermost end of the suspension insulator 3, and a hanging fitting 9 is rotatably supported at the lower end via a connecting bolt 8. The support fitting 6 is suspended from the lower end of the hanging fitting 9. A corona prevention nut 10 of the present invention is screwed into the threaded portion 8a of the connecting bolt 8. The corona prevention nut 1
0 is manufactured from a commonly available hexagonal nut as shown in FIG. A storage groove 10b is formed. Then, the split pin 11 is inserted into the insertion hole 8b penetrating the threaded portion 8a of the connecting bolt 8 to eliminate relative rotation between the connecting bolt 8 and the corona prevention nut 10, and the nut 1
0 from falling off the connecting bolt 8. Further, the outer peripheral edge of the head of the corona prevention nut 10 is chamfered 10c so as to have a slightly larger roundness than the head of a general hexagonal nut.

Further, corona prevention nuts 10 are also used for the four connecting bolts 8' to 8' that support the wire clamp fittings attached to the connecting yoke 6a of the support fitting 6.

Next, the function of the corona prevention nut 10 constructed as described above will be explained.

As shown in FIG. 1, the suspension insulator 3 and the support metal fittings 6
For example, in connection parts such as connection bolts 8, 8' to 8', which are not surrounded by parts with the same potential, electric field concentration tends to occur, and corona is particularly likely to occur from acute angle parts such as the tips of split pins 11. It is more likely to occur. However, the corona prevention nut 10 has a storage groove 10b on the bottom surface 10a side, and the split pin 1 is inserted into the groove 10b.
1, a space where a shielding effect exists due to the connecting fitting 7 itself, that is, a shielding angle α where electric field concentration does not occur as shown in FIG.
The split pin 11 can be accommodated in the area formed by the nut 10 with plenty of room.
Alternatively, it is possible to prevent electric field concentration due to the acute angle portion of the cotter pin 11, thereby eliminating the occurrence of corona.
The corona prevention nut 10 is attached to the split pin 1.
Since the nut 10 can be housed with plenty of room within the area where the shielding effect of the connecting fitting 7 can be obtained, the entire nut 10 can be made smaller and lighter. It can be easily manufactured by simply forming a chamfer 10c on the head, and it is also easy to handle and reduce costs.

By the way, the conventional corona prevention nut 24 shown in FIGS. 9 and 10 has a housing groove 24a formed on the head side and stores the split pin 25 therein so that its tip is not exposed to the outside. , Natsuto 24
must be made larger. However, since the corona prevention nut 10 of the present invention has the storage groove 10b formed on the bottom side as described above, the tip of the split pin 11 does not necessarily have to be accommodated in the storage groove 10b, and the split pin 11 can be placed at the shielding angle α. The nut can be accommodated with plenty of room within the area of , therefore there is no need to increase the size of the nut, and the occurrence of corona can be reliably prevented.

Next, a second embodiment of the present invention will be described with reference to FIGS. 5 and 6. Note that members having the same functions as those in the first embodiment are designated by the same reference numerals, and explanations thereof will be omitted.

As shown in FIG.
are rotatably connected by bolts 13, support metal fittings 6 for power transmission lines are attached to both ends of the connection plate 12, and the connection bolts described in the first embodiment are installed between the connection plate 12 and the support metal fittings 6. 8. A corona prevention nut 10 and a split pin 11 are attached.

In Figure 5, the electric field due to the equipotential lines was calculated for the rectangular area indicated by the two-dot chain line.
An electric field map as shown in the figure was obtained. This shows that no electric field concentration occurs near the head of the corona prevention nut 10 and near the split pin 11. On the other hand, in the conventional structure for preventing the nut 24 from falling off as described in FIG. 8, it can be seen that electric field concentration occurs near the tip of the split pin 25, as shown in FIG.

Note that the present invention can also be embodied in the following embodiments.

(1) Forming a plurality of split pin storage grooves 10b in the corona prevention nut 10.

(2) The shape of the storage groove 10b can be any shape such as Ω-shape or ∧-shape.

Effects of the Invention As described in detail above, the present invention has the advantage of being able to reliably prevent the occurrence of corona, as well as making the entire nut smaller and lighter, making it easier to manufacture and reducing costs.

[Brief explanation of drawings]

1 to 4 show a first embodiment of the present invention,
Fig. 1 is a front view showing a hanging insulator device for power transmission lines, Fig. 2 is an enlarged front view of the main parts, and Fig. 3 is A-A of Fig. 2.
A sectional view taken along line A, FIG. 4 a perspective view of a corona prevention nut, FIGS. 5 and 6 a second embodiment of the present invention, and FIG. 5 a side view showing a hanging insulator device for a power transmission line. , FIG. 6 is an electric field field map diagram based on equipotential lines, FIG. 7 is an electric field field map diagram in a conventional example, and FIG. 8 is a front view showing a connecting bolt and nut used in a conventional low-voltage overhead wire fitting device.
Fig. 9 is a front view showing the conventional example, Fig. 10 is a sectional view taken along line B-B in Fig. 9, Fig. 11 is a front view showing the conventional example, and Fig. 12 is taken along line C-C in Fig. 11. FIG. 7... Connecting metal fittings, 8... Connecting bolts, 8a...
Threaded part, 8b...Insertion hole, 9...Hanging metal fitting, 10
... Corona prevention nut, 10a ... Bottom, 10
b...Storage groove, 11...Cotter pin.

Claims (1)

[Scope of Claims] 1. A corona prevention nut characterized by having a notch extending diametrically from the bottom surface of the nut toward the head side to form a split pin storage groove. 2. The corona prevention nut according to claim 1, wherein the outer periphery of the head of the nut is roundly chamfered.