JPH01126125A - Icing and snowing prevention apparatus for overhead power transmission line - Google Patents

Abstract

PURPOSE:To solve problems such as the dip increase of an electric wire and softening of said wire due to overheat by preventing the abnormal overheating of an apparatus through saturating a magnetic flux generated in a split sleeve, while an applied current is low. CONSTITUTION:An icing and snowing prevention apparatus is constituted by a ferromagnetic material split sleeve 1 having a thickness of 3mm and less, of which magnetic characteristic is such that a magnetic flux tends to be saturated when a magnetic field has a strength of at least scores of Oe(oersted), and a clamping means 2 binding said split sleeve 1 and fastening it to an electric wire A. Then, a magnetic flux is generated in said ferromagnetic split sleeve 1 by a current applied to said wire A, and said split sleeve 1 generates beat by iron loss. On the other hand, said magnetic field grows larger as the current applied to said wire A becomes higher, but when the strength of said magnetic field exceeds scores of Oe, the magnetic flux tends to be saturated and therefore the calorific value also has a tendency to be saturated. Consequently, it is possible to control the abnormal generation of heat of an apparatus at the time of 100% power application in summer and so on and softening of the wire A caused by such generation of heat.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an icing and snow prevention device employed on overhead power transmission lines as part of snow damage countermeasures.

[Conventional technology]

As one method to eliminate ice, snow, and falling snow on overhead power transmission lines, a ring-shaped low-Curie material is attached to the wire, and the property of the material to become magnetic at temperatures above the Curie point and the ability of the overhead power transmission line to be There is a method in which the electric current flowing through the electric wire is used to generate heat in the mounting material in winter due to iron loss, and this heat is used to prevent snow from accreting and to melt the snow.

This method can be used during high temperatures such as summer when the Curie point is exceeded.
The mounting material changes to properties similar to non-magnetic materials, and the amount of heat generated by iron loss is reduced, so there is less softening (strength reduction) of the wire due to overheating of the mounting material, which is advantageous in terms of preventing wire breakage. It has drawbacks.

(Problem to be solved by the invention) Low Curie materials have inferior magnetic properties at low temperatures compared to ferromagnetic materials, so they cannot be expected to generate a large amount of heat per unit volume. The practical equipment is
It is inevitable that the volume will be large, or in other words, the weight will be heavy.

This is because if the size is restricted, it will interfere with the weather conditions under which it would be effective, leading to insufficient capacity in cold regions, leading to concerns about accidents such as damage from falling ice and snow and the collapse of steel towers.

However, heavy equipment becomes difficult to install on overhead power lines. In addition, heavy equipment causes increased slack in the electrical wires,
This will be disadvantageous in terms of safety management.

On the other hand, if the low Curie material is replaced with a ferromagnetic material that has a large calorific value per unit volume, the weight of the device can be reduced, but in this case, it is not possible to control the calorific value at low and high temperatures. Excessive heat generation causes the wires to soften, greatly reducing the safety of power transmission lines.

[Means for solving problems]

In order to eliminate the above-mentioned problems, this invention provides a thick film having magnetic characteristics such that the magnetic flux B tends to saturate when the magnetic field H is at least several + Oe (Oersted), as shown in FIGS. 1 to 3. Split sleeve 1 made of ferromagnetic material with a length of 3ms or less
This and the clamping means 2 for binding and fixing this split sleeve onto the electric wire A constitute an ice and snow prevention device.

[Effect]

A magnetic flux B is generated in the ferromagnetic split sleeve 1 by the current applied to the electric wire, and the split sleeve generates heat due to iron loss. The amount of heat generated Q is expressed as (where f: frequency, k, , kt: constant), and this heat prevents ice and snow from accreting on the electric wire.

On the other hand, the magnetic field H created by installing the split sleeve 1 increases as the current I flowing through the wire increases, but when the magnetic field H exceeds several + Oe, the above +11
Since the magnetic flux B in the equation tends to saturate, the heat generation 11Q also tends to saturate, so even without using a low Curie point material,
Abnormal heat generation of the device when energized at 100% during summer and the like and the resulting softening of the wires are suppressed.

The reason why the magnetic field H at which the magnetic flux B tends to saturate is set to several + Oe is as follows.

For example, if a split sleeve 1 with a thickness of 3 fins is attached to the following electric wire, the generated magnetic field H at 50% energization will be calculated by setting the current value to 1 and the distance from the center of the wire to the center of the magnetic field to r(
(See Figure 3), ■ H-□... From the equation (2), 2πr A CS R160' □Generated magnetic field H-400eA
CS R810' □Generated magnetic field H=600e.

At this time, assuming that the magnetic flux B generated in the sleeve is not saturated, the magnetic flux B also increases as the generated magnetic field increases, and the amount of heat generated by the sleeve naturally increases. However, this obviously causes excessive heat generation when 100% electricity is applied.

Therefore, as can be seen from the B-H characteristic graph in Figure 4, the maximum value is 11~TMax when the conducting current reaches fl.
In order to prevent the amount of heat generated from increasing during (100% energization), the above value is selected. The reason why this numerical value is not specified is that the device performance is required depending on the usage conditions.

Next, the reason why the thickness of the split sleeve 1 is set to 3 cranes or less is because, as can be seen from (2) 2 above, H is inversely proportional to r.
It is desirable that the sleeve thickness be as thin as possible;
Thin sleeves are lightweight, so there is less increase in the slack of the wire, and when it exceeds 3N, a very special ferromagnetic material with -H characteristics is required, but such materials are difficult to obtain. It depends. However, if it is extremely thin, there will be problems with strength and durability, so it is not preferable.

The length of this split sleeve may be determined as appropriate, taking into account ease of handling, adhesion of the split portion, spacing for attachment to electric wires, etc.

〔Example〕

The illustrated device is a specific example of the present invention, and the split sleeve 1 is made of iron, and its surface is galvanized to prevent corrosion. Further, the length E of the split sleeve 1 is about 50 fins, and the thickness t is about 2 to 3 fl.

On the other hand, as the clamping means 2, a U-shaped clamp (width W=5) made of a non-magnetic material, especially aluminum that is easily plastically deformed, is compressed and deformed as shown in FIG. The idea is to make it take root. When this device is attached to the electric wire A at a predetermined pitch, the above-mentioned action prevents ice and snow from accumulating on the electric wire.

(Effects) As described above, according to the present invention, the magnetic flux generated in the split sleeve is saturated while the current is low, thereby preventing abnormal overheating of the device. The device can be made lighter by being made of ferromagnetic material that generates a large amount of heat per unit, and it solves the problem of poor attachment to electric wires.
This has the effect of being able to solve both the problem of increased slackness of the wire and the problem of softening due to overheating of tX.

[Brief explanation of the drawing]

FIG. 1 is a split perspective view showing an example of the device of the present invention, and FIG.
3 is a sectional view taken along the line X--X in FIG. 2, and FIG. 4 is a graph showing the B-H characteristics of the device of the present invention. 1... Split sleeve, 2... Clamping means, A... Electric wire. Patent applicant: Sumitomo Electric Industries, Ltd.

Claims (1)

[Claims] When the magnetic field H is at least several tens of oersted, the magnetic flux B
A device for preventing icing and snow on overhead power transmission lines, comprising a split sleeve made of ferromagnetic material with a thickness of 3 mm or less and having magnetic properties that tend to saturate, and a clamping means for binding and fixing the split sleeve onto the wire. .