JP2910927B2 - Overhead transmission line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a means for reducing the sag of an overhead power transmission line, in particular, the sag of the lowest phase electric wire (to increase the ground clearance).

[Conventional technology and its problems]

The overhead transmission line is stretched in accordance with an increase in the operating temperature, so that the sag is increased, and accordingly, the isolation distance under the line is reduced. Since the distance below the line is determined by law, the height of the tower supporting the transmission line is set on the assumption of the worst conditions.

However, if the voltage or current is increased to increase the power transmission capacity, or if a house or the like is constructed under the line, the isolation distance under the line may be insufficient.

On the other hand, a device that does not increase the sag even when the use temperature of the electric wire increases has been used. This is one in which a coil spring is inserted between the wire clamp and the tension insulator series so as to be compressed by the wire tension. In this way, when the temperature rises and the wire expands, the wire tension decreases and the coil spring expands, and conversely, when the temperature decreases and the wire shrinks, the wire tension increases and the coil spring compresses and contracts. The wire tension is kept almost constant and there is no change in slack.

However, since this device absorbs the expansion and contraction of the electric wire by the expansion and contraction of the coil spring, it is restricted by the electric wire tension and the span length, and has a drawback that its application range is narrow and it can be applied only to the tension portion. In addition, when applied to an existing transmission line, the jumper device needs to be modified, resulting in extremely high costs.

[Means for solving the problem and its operation]

The present invention provides an overhead power transmission line that solves the above-described problems, and has a configuration in which a medium-phase current of an overhead transmission line is set to an upper-phase current, a lower-phase current is set to a middle-phase electric wire, and a distance between the phases is set. It is characterized by being suspended using a shorter insulating suspension member.

With this configuration, the middle-layer electric wire is pulled up to the upper-phase electric wire, and the lower-phase electric wire is pulled up to the middle-phase electric wire. Therefore, the sag of the lower-phase electric wire is significantly reduced, and the separation distance under the wire can be increased.

In the above configuration, when the upper-phase electric wire is suspended from the overhead ground wire by using an insulating suspension member shorter than the distance between these wires, it is possible to further reduce the sag of the lower-phase electric wire. is there.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In the figure, 1A ~
1C is a steel tower, 2 is a tension insulator series, 3 is a suspension insulator series, 4a is an upper phase electric wire, 4b is a middle phase electric wire, 4c is a lower phase electric wire, and 5 is an overhead ground wire.

The present invention suspends the medium-phase electric wire 4b on the upper-phase electric wire 4a using the insulating suspension member 6 in such an overhead-phase electric wire path,
Further, the lower-phase electric wire 4c is suspended from the middle-phase electric wire 4b by using an insulating suspension member 6. Length L of each insulating suspension member 6
Is shorter than the correlation distance H of the electric wire. For this reason, the middle-phase electric wire 4b is raised to the upper-phase electric wire 4a, and the lower-phase electric wire 4c is raised to the medium-phase electric wire 4b, so that the lower-phase electric wire 4c has a reduced sag and the isolated distance under the wire can be increased. Note that the dotted line is a catenary curve of each electric wire before the insulating suspension member 6 is attached, and the lower transmission line 4c has been lifted from the position of the dotted line to the position of the solid line.

It is preferable that the insulating suspension member 6 is as light as possible, and it is preferable to use a lightweight long trunk insulator made of resin, a rope, or the like. The length L of the insulating suspension member 6 is 50 to
Selected to be around 70%. Further, it is preferable that the insulating suspension member for suspending the lower-phase electric wire to the medium-phase electric wire is shorter than the insulating suspending member for suspending the intermediate-phase electric wire to the upper-phase electric wire.

In the case of FIG. 1, since the span between the towers 1A and 1B is long, three insulating suspension members 6 are used to suspend the middle-phase electric wire 4b on the upper-phase electric wire 4a. Since the span between the towers 1B and 1c is short, the middle-phase electric wire 4b is suspended from the upper-phase electric wire 4a by one insulating suspension member 6. In this way, the number of used insulating suspension members is adjusted by the span length.

Further, as shown by a dashed line in FIG. 1, when the upper-phase electric wire 4a is suspended from the overhead ground wire 5 using an insulating suspending member 7 shorter than the distance between these lines, the sag of the lower transmission line 4a is reduced. It is effective to further reduce. Since the overhead ground wire 5 does not have a temperature rise due to the supplied current, the change in sag is small, and this is also effective in reducing the sag.

FIGS. 2A to 2F are models showing the increase / decrease of the sag of each electric wire depending on how the insulating suspension member 6 is attached. The interphase distance is 100, and the length of the insulation suspending member 6 is 60
When the span lengths are set to 840 and 1750, the increase / decrease of the sag of the electric wire in each model is calculated, as shown in Table 1. + Indicates an increase in the sag and-indicates a decrease in the sag.

According to this result, as shown in FIGS. 2 (a) to 2 (c), the middle phase is the upper phase, the lower phase is the middle phase,
The lower phase electric wire can be suspended by the insulating suspension members 6 respectively.
It turns out that it is the most effective in reducing the sag of 4c. In the above calculation example, the span length with respect to the interphase distance is set to be significantly shorter than that of the actual transmission line.

From this calculation result, it is considered that it is sufficient to insert an insulation suspending member at one place of the span for a transmission line with a span length of about 200 m. Is high.

〔The invention's effect〕

According to the present invention as described above, the medium-phase current is converted to the upper-phase current by the insulating suspension member, the lower-phase current is set to the medium-phase electric wire,
With a simple structure of hanging each, the sag of the lower phase electric wire can be surely reduced. In addition, when the insulation suspension member is attached, the tension of the middle-phase wire is lower than that of the upper-phase wire, and the lower-phase wire is lower in tension than the middle-layer wire. It becomes difficult to do. In addition, since the electric wires are connected by the insulating suspension member, the twisting becomes difficult, so that there is no possibility that snow accretion develops into a cylindrical snow due to the twisting of the electric wires, and the installation of a twist preventing damper for preventing snow accumulation can be omitted. There is a possibility.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an overhead power transmission line according to one embodiment of the present invention, and FIGS. 2 (a) to (f) show the increase / decrease of the sag of each electric wire due to the difference in the mounting method of the insulating suspension member. FIG. 1A to 1C: steel tower, 4a: upper phase electric wire, 4b: middle phase electric wire, 4c: lower phase electric wire, 5: overhead ground wire, 6.7: insulating suspension member.

Continuation of the front page (72) Inventor Takuo Okawa 500, Kiyotaki-cho, Nikko-shi, Tochigi Furukawa Electric Co., Ltd. Nikko Works (56) References JP-A-50-100571 (JP, A) JP-A-53-147997 ( JP, A) JP-A-2-254915 (JP, A) JP-A-63-257409 (JP, A) Actually open Showa 53-143089 (JP, U) Actually open Showa 54-1198 (JP, U) Actually open Sho 57-101522 (JP, U) Shokai Sho 57-195329 (JP, U) Shokai Hei 2-91417 (JP, U) Japanese Patent Publication No. Sho 49-25993 (JP, B1) (58) Fields investigated (Int) .Cl. ⁶ , DB name) H02G ^7/ 00-7/22

Claims (2)

(57) [Claims] 1. An overhead transmission line, wherein an intermediate transmission line of an overhead transmission line is suspended to an upper phase transmission line, and a lower phase transmission line is suspended to an intermediate phase transmission line by using an insulation suspension member shorter than a distance between phases. . 2. The overhead transmission line according to claim 1, wherein the upper phase electric wire is suspended from the overhead ground wire by using an insulation suspension member shorter than a distance between the overhead ground wires.