JPH0652966B2 - Snow damage prevention type electric wire - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electric wire capable of properly preventing damage caused by snow adhering to the electric wire.

[Prior Art and Problems] Overhead power transmission lines (including overhead ground lines) are composed of twisted wires having a circular cross section in which strands are concentrically twisted. When snow falls on such an electric wire, the snow slides down the electric wire while rotating along the twist groove of the electric wire. At this time, there is no problem because dry snow falls as it is, but in the case of wet snow, it sticks to the surface of the wire and does not easily fall. The snow on top of the electric wire slips down while rotating along the twist groove again. For this reason, the snow starts to rotate around the wire without falling, and finally the snow sticks around the wire in a tubular shape, and the tubular snow itself rotates further around the wire due to the weight of the snow accumulated above. And grow up. When the cylinder snow starts to rotate in this way, the snow continues to grow and grow without falling, and even grows up to several tens of centimeters in diameter. Occasionally, even the worst case of a collapse is reported.

In order to prevent such an accident, there is a proposal to prevent the rotation of the snow cylinder by fitting a ring to the electric wire or forming a fin-shaped projection, but it is effective only for a specific snow quality. Not enough.

Furthermore, in order to directly melt the snow, there are proposals to attach a magnetic body to an electric wire and use heat generated by hysteresis loss, or to wind a heater directly on the electric wire, but the heat generation is insufficient or a large amount of power is consumed. And not always practical.

The technology of winding a spirally formed filament on the outer circumference of an electric wire was originally developed for the purpose of preventing wind noise, but by winding such a spiral rod, the spiral rod is It was found that it could obstruct the rotation of the snow as it interferes with the snow that rolls along the groove of the twisted wire and slides down.

If the rotation of the snow is prevented in this way, the snow loses its balance due to its own weight before it grows to the above-mentioned snow, and finally falls from the electric wire.

However, by winding the spiral rod, growth of the snow is surely prevented, and wire breakage and collapse of the tower are prevented, but the snow whose rotation is blocked by the spiral rod is immediately stopped. It does not fall and becomes a snow mass that causes an imbalance due to its own weight, and then falls.
The ground clearance of ultra-high voltage transmission lines in recent years is extremely high, and snowflakes that have fallen with acceleration from the above heights have an unexpected destructive force and cause considerable damage to human bodies and structures under the line. To get.

On the other hand, according to the results of automatic observation of the amount of snowfall on the electric wire over the entire winter period, it is rare that a single snowfall will cause snowfall, and the electric wire will not actually be damaged. It was also found that most of the time, the snow would soon stop to some extent and then fall to some extent.

Therefore, instead of blocking the snow that is going to rotate by the spiral rod and unnecessarily creating snow clumps to unbalance and drop, it is not enough to actually drop the wires as shown in the above observation results. Since most of the accumulated snow is kept in a snowcapped state without being dropped, and if the snowcap is melted and removed by the heat generated by solar radiation or electricity when the snow stops It is possible to prevent accidental damage due to a lump falling. Further, if the snow caps are dispersed in smaller snowflakes and dropped, snow damage can be similarly prevented.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and in the case of snow accretion that does not actually damage the electric wire, rather than dropping snow accreted on the electric wire as a snow lump. Rather, it causes it to adhere to the wires as snowcaps and melts and removes the snowcaps due to insolation or electric heat, while in the case of full-scale heavy snow that causes actual damage to the wires It is an object of the present invention to provide a new snow damage prevention type electric wire configured so that it can be dropped before it grows into snow.

[Summary of the Invention] In the present invention, a spiral rod is doubly wound around an outer circumference of an electric wire, and by applying the winding condition, snow accretion to a certain extent can be held in a snow-covered state without dropping it. It can be dispersed in small snowflakes, which prevents mechanical damage to the snowflakes, even though there is no actual damage to the wires, and accidentally damages the human body, structures, or agricultural products under the wires. On the other hand, if the snow is heavy enough to actually damage the wires, the original function of the spiral rod is exerted to protect the wires or the tower from damage.

[Examples] Hereinafter, the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows one embodiment of the present invention, in which a first spiral rod 2 which is closely attached to the outer circumference is wound around an electric wire 1, and a second spiral rod 3 is formed in a relationship intersecting with the first spiral rod 2. Is wound. A spacer 4, for example, is arranged on the second spiral rod 3 to hold the relationship in which the spacer 4 is separated from the outer periphery of the first spiral rod 2 as well as the electric wire 1.

FIG. 2 is a cross-sectional view taken along the line AA showing the positional relationship of the above-described winding, and the first spiral rod 2 and the second spiral rod 3 are shown.
A gap G is formed between and.

If the spiral rod is cross-wound double with the gap G as described above, the sliding movement of snow on the electric wire is largely prevented and the snow-covered state is maintained. Therefore, as already described, the snow is melted and disappears due to the subsequent heat generated by solar radiation and electricity.

Therefore, according to the above configuration of the present invention, the gap G
Therefore, there is another feature that it is easy to generate vibration due to wind, etc.Synergistic action of such vibration and gap causes the snowcap itself to become small snowflakes, and even if it falls, it will not cause any actual damage. The effect of dispersing and dropping can be exhibited.

FIG. 3 is an explanatory view showing another embodiment according to the present invention in which the dispersed falling of the snow caps is not passively entrusted to wind pressure vibration or the like, but is actively made into small pieces of snow and dropped. According to the present embodiment, the power source is obtained from the current transformer 5, the motor 6 is rotated, and the driving device 8 is driven via the clutch 7. By this driving, the second spiral rod 3 causes the outer circumference of the electric wire 1. It is rotated along with or moved back and forth in the longitudinal direction of the electric wire 1 to positively disperse the snow that has become the snow and attached to the small snowflakes to eliminate the damage caused by the falling snow. In order to exert such a role, it is desirable to select an aluminum alloy having high strength and wear resistance as the material of the spiral rod, instead of ordinary aluminum.

On the other hand, spiral rod winding as a wind noise prevention measure already has many achievements all over the country, and this is no exception in snowfall areas. Since these were originally wired for the wind, when winding this around the wire 1, there is no danger of twisting the wire and winding the spiral rod to generate lift and cause galloping vibration. You need to do it. Therefore, in consideration of canceling the lift forces to each other and ensuring the aerodynamic stability of the electric wire,
Winding direction of the spiral rod as a measure against wind noise is
As shown in FIG. 5 or 6, the S and Z mixed windings are usually used. That is, FIG. 5 shows an example in which S windings 2s and Z windings 2z are alternately or randomly wound in the longitudinal direction of the electric wire 1, and FIG. 6 shows adjacent conductors 1 and 1 of the multiconductor transmission line.
^It shows an example in which the S winding 2s and the Z winding 2z are mixed and wound between ⁻ .

Consider a case in which an electric wire having a spiral rod of S and Z mixed windings has snow accretion to the extent of snow, and the twisted direction of the outermost layer of the snow-covered electric wire is S twist.

The snowcap begins to melt due to solar radiation and electric heat generation, and a water film is formed between the snow and the outer surface of the wire, making it easier to move. Even if the snow cover starts to move along the twist groove of the S-twisted wire in this way, the movement of the snow cap is prevented because the rod 2z exists in the Z-wound spiral rod 2z portion so as to intersect with the S-twist groove. Has the effect of However, the winding direction of the S-winding spiral rod matches the S-twisting direction of the electric wire, and the S-winding spiral rod does not have the effect of blocking snow that tends to move. Therefore, the snow covered on the S-shaped spiral rod 2s slides down as it is, and becomes a snow lump state and falls to the ground. The destructive effect of such a moist snow mass that has begun to melt is very great, and the actual damage is great.

In the present invention, in order to prevent such damage,
As shown in FIG. 4, in the portion where the first spiral rod 2 is in the winding direction which is the same as the twisting direction of the electric wire 1,
The second spiral rod 3 in the opposite direction to the first spiral rod 2 is wound. In this way, even if the snow cover slips, the second spiral rod 3 blocks it, prevents it from falling into a snow lump, and eventually melts and disappears.

The above snow damage prevention measures for such existing wind noise prevention electric wires may be carried out by selecting only the places where houses, roads, structures, vinyl houses, agricultural products, etc. exist below the electric wires.

The existing countermeasures may be the above, but it goes without saying that the technical idea can be applied as it is to the new location.
In this case, in order to maintain the fitting of the respective spiral rods in the best condition, the molding inner diameter of the first spiral rod 2 wound around the electric wire 1 should be smaller than the outer diameter of the electric wire 1, and the second spiral rod It is necessary to make the molding inner diameter of 3 smaller than the winding outer diameter of the first spiral rod 2. Forming in this way and winding each one facilitates the construction of cross winding, and makes it possible to perform winding with excellent adhesion without using any locking piece. There is no problem even if you run an airborne vehicle on the section, for example, and even if it melts due to a lightning strike, you can eliminate the possibility that the spiral rod will hang and cause a short circuit accident. is there.

In order to clarify the snowfall prevention effect due to the double cross winding of the spiral rod as described above, the gap δ between the electric wire 1 and the second spiral rod 3 caused by the cross winding (see FIG. 4). ) Was changed for various snowfall experiments.

In the experiment, shave ice in a freezing room at -2 ° C, make it look like snow and drop it on an electric wire, raise the room temperature to + 2 ° C with the snow height of 40 mm, and check if there is any snowfall thereafter. It is something to look up. The snow that did not fall in this experiment melted and disappeared after the lapse of time as expected.

The results are shown in Table 1.

As is clear from Table 1, the larger the gap δ is, the more effective the snow-holding effect is, and the present invention is in good agreement with the starting technical idea in solving the problem.

That is, there is a critical condition for the gap δ, and the critical value is 1.5 mm, and it is necessary for the present invention to satisfy the condition of δ ≧ 1.5 mm in order to exert its effect. Recognize.

According to the present invention, as described above, it is possible to prevent the damage due to the falling of snowflakes by melting and melting the usual snowfall, but the wind pressure increase due to the double winding of the spiral rod. Concerns still remain.

In order to investigate this problem, the case of the conventional single-wire S-direction spiral rod winding and the case of cross-winding the second spiral rod of various diameters on the S-direction spiral rod thus wound. The comparison experiment of the aerodynamic characteristics with

That is, an electric wire obtained by winding an S-direction spiral rod having a diameter of 6 mm and a spiral pitch of 250 mm on a transmission line of ACSR410 mm ² and an electric wire further having a Z-direction spiral rod having a wire diameter of 2 to 8 mm cross-wound thereon, Wind speed 40
The respective drag and lift characteristics were measured at m / S.

FIG. 7 shows the measurement result of the drag force characteristic, and FIG. 8 shows the measurement result of the lift force characteristic. The diameter of the second spiral rod is 8 mm.
There is no significant difference up to about mm from the case of single winding, and it can be seen that there is no possibility of change in wind pressure characteristics due to double cross winding.

As a result, it was found that the snow damage-preventing electric wire according to the present invention can cooperate with the conventional wind noise preventing electric wire to establish a coexistence relationship.

[Effects of the Invention] As described above, according to the electric wire of the present invention, snow accreted on the electric wire is kept as snowcaps or dispersed in small snowflakes as long as snow does not actually damage the electric wire, resulting in a snow mass. While it is possible to sufficiently eliminate the damage given to the lower part of the electric wire by falling, it protects the electric wire and the tower from the formation of snowflakes against heavy snow, and also reliably prevents wind noise and contributes to the environment improvement. , Its significance on the industry or on the public is very significant.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing a specific example of an electric wire according to the present invention, FIG. 2 is a sectional view taken along the line AA in FIG. 1, and FIG. 3 is another specific example according to the present invention. FIG. 4 is an explanatory view showing yet another specific example according to the present invention, and FIGS.
FIG. 7 is an explanatory view showing a situation of winding a spiral rod of a conventional wind noise prevention type electric wire, and FIGS. 7 and 8 are diagrams showing results of wind pressure characteristic experiments. 1: Electric wire, 2: First spiral rod, 3: Second spiral rod, 8: Drive device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Yamamoto, Kenji Yamamoto, 1500 Kawajiri-cho, Hitachi-shi, Ibaraki Inside the Toyoura factory, Hitachi Cable Co., Ltd. Electric Wire Co., Ltd. (56) Reference JP-A-49-30888 (JP, A)

Claims (3)

[Claims] 1. A first spiral rod, which is formed in advance, is wound around the outer circumference of an electric wire, and has a gap in the opposite direction to the first spiral rod and with the first spiral rod, A snow damage-prevention electric wire formed by winding a second spiral rod formed in advance. 2. The snow damage-preventing electric wire according to claim 1, wherein the second spiral rod is configured to be rotatable or linearly movable by power driving. 3. A molded inner diameter of a first spiral rod wound around the outer circumference of an electric wire is smaller than an outer diameter of an electric wire, and a molded inner diameter of a second spiral rod wound crossing over the electric wire is the first inner diameter of the first spiral rod. The spiral rod is wound to have a diameter smaller than the outer diameter of the spiral rod after winding, and each is wound, and the gap formed between the outer surface of the wire and the inner surface of the second spiral rod is δ. At this time, a snow damage prevention type electric wire configured so that δ ≧ 0.15 mm.