JP2831659B2 - Heating wire and snow melting wire using it - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a heating wire used for snow melting of overhead power transmission lines and the like, and a snow melting wire using the heating wire.

[Conventional technology]

Various methods have been studied and implemented to prevent snow accumulation on overhead transmission lines. A typical example is a method of preventing snow accumulated on electric wires from developing into a cylindrical shape by attaching a snow-resistant ring, and wrapping a fluororesin (Teflon) tape around the electric wires to slide the snow on the snow. There is a method of dropping.

These are methods of preventing snow from accumulating physically.However, in some places where environmental conditions under transmission lines are severe, a small amount of snow may not be allowed. It is necessary to dissolve the snowfall or the snowfall. Several methods have been proposed and implemented for this purpose. For example, winding a low Curie point wire around an electric wire, using a magnetic field generated by the electric current of the electric wire to generate heat at a low temperature, melting snow, winding an insulated heating wire around the electric wire, bonding the insulated heating wire to the electric wire, A method has been put to practical use, in which a current transformer (CT) is used as a power source to supply current and melt snow with Joule heat.

〔Task〕

The method using a hard-to-wear ring and fluororesin tape cannot be applied to places where the environmental conditions under the transmission line are severe because the measures against snowfall are not sufficient.

In addition, since the method of winding the low Curie point wire uses a magnetic field due to the electric current of the electric wire, the snow melting effect is not obtained unless a large electric current flows through the electric wire. Usually, snow accumulates during the night when the load on the transmission line is low,
To obtain a sufficient snow melting effect even when the transmission current is small,
It is necessary that the low Curie point wire is almost tightly wound around the outer periphery of the electric wire. However, doing so increases the load on the wire,
There are problems such as a drastic increase in slack and an excessive load on the tower.

In addition, the method of winding the insulated heating wire has a problem that the cost is increased due to the necessity of CT, and the life is limited due to deterioration of the insulator.

[Means for solving the problem and its operation]

The present invention has been made in view of the above-mentioned problems of the related art, and provides a new heating wire. The configuration of the heating wire is a spiral ridge made of a conductive metal around a core wire made of a ferromagnetic material. Is formed such that the cross-sectional area of the conductive metal ridge is larger than the cross-sectional area other than the ridge.

When an alternating current is passed through such a heating wire, the current mainly flows spirally along a ridge having good conductivity, so that an alternating magnetic field is effectively applied to the core wire made of a ferromagnetic material to generate heat. Will do. An iron wire, a steel wire, a low Curie point wire, or the like is used as the core wire made of a ferromagnetic material, and aluminum or copper is used as the conductive metal.

The present invention also provides a snow-melting electric wire using the above-described heating wire, and the configuration is such that the above-described heating wire is twisted as an element wire on the outermost layer of the stranded conductor,
It is characterized by being spirally wound around the outer periphery of the stranded conductor.

When the heating wires are arranged in this way, a part of the current flowing through the stranded conductor flows into the heating wires, and the heating wires generate heat and melt the snow.

〔Example〕

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

FIGS. 1A and 1B show an embodiment of a heating wire according to the present invention. The heating wire 1 includes a core wire 2 made of a ferromagnetic material.
An aluminum coating 4 having a helical ridge 3 is integrally formed on the outer periphery of the helical member. The spiral ridge 3
As is clear from FIG. 1 (a), the aluminum coating 4
Among them, the cross-sectional area of the ridge 3 is formed to be larger than the cross-sectional area other than the ridge 3.

The heating wire 1 having such a structure is extrusion-coated with an aluminum coating 4 having a ridge 3 on the outer periphery of a core wire 2 by a continuous extrusion coating method such as a conform method, and the extruded composite wire is wound while being twisted. In this way, it is possible to manufacture easily by rotating the winding side or the supply side to give a torsion when rewinding after winding once.

The ridge 3 may be one, but it is more effective to form a plurality of ridges. The helical pitch of the ridge 3 is preferably as small as possible in order to generate a stronger magnetic field.

When a current flows through the heating wire 1 as described above, most of the current flows through the ridge 3 having good conductivity, and since the ridge 3 has a spiral shape, the coil is wound around the iron core. And the flowing current generates a strong magnetic field in the core wire 2 of the ferromagnetic material, causing a large iron loss.
Heat can be generated effectively.

FIG. 2 shows an embodiment of the snow melting electric wire according to the present invention. 1
Is a heating wire as described above, 6 is a steel wire, and 7 is an aluminum wire. That is, this snow-melting electric wire 5 has an aluminum wire 7 and a heating wire 1 in the outermost layer of a steel core aluminum stranded wire.
It is twisted every other book. Since the snow-melting electric wire melts snow attached to the surface of the electric wire, it is effective to twist the heating wire 1 to the outermost layer. The number of heating wires 1 may be determined in relation to the load current.

If a low Curie point material is used as the ferromagnetic core wire of the heating wire 1, power loss at a temperature free from snow can be reduced. The low Curie point material is a material that loses the properties of a ferromagnetic material at a certain temperature (for example, a temperature slightly higher than 0 ° C.), and an Fe—Ni—Cr—Si alloy is known.

FIG. 3 shows another embodiment of the snow melting electric wire according to the present invention.
The snow melting electric wire 8 is obtained by spirally winding the above-mentioned heating wire 1 around the outer periphery of a steel core aluminum stranded wire 9 composed of a steel wire 6 and an aluminum wire 7. This example is
It is suitable for making an already installed electric wire into a snow melting structure. Although the drawing shows an example in which one heating wire 1 is wound, the number of heating wires 1 and the winding pitch may be determined according to the snow melting target and the load current flowing through the steel core aluminum stranded wire 9.

The heating wire 1 may be long and wound around an electric wire by a winding machine, or a length suitable for handling, such as an armor rod, and formed into a spiral shape in advance according to the diameter of the electric wire and wound. It may be.

Comparing the snowmelt electric wire of Fig. 3 with the electric wire wound with the conventional low-Curie wire,
It is the same in that heat is generated by the magnetic field generated by the current flowing in the electric wire. However, in the snow melting electric wire shown in FIG. 3, the current shunted to the heat generating wire 1 also flows in a spiral shape along the ridge. There is another heating principle in which a magnetic field is generated and the ferromagnetic core heats up. Therefore, the calorific value is remarkably improved as compared with the conventional one, and effective snow melting can be performed.

〔The invention's effect〕

As described above, in the heating wire according to the present invention, the current spirally flows around the ferromagnetic core, so that the ferromagnetic core is efficiently heated by the magnetic field, thereby increasing the size. The calorific value can be obtained. Further, in a snow melting electric wire using such a heating wire, since the heat generation amount of the heating wire is large, snow melting can be performed efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. -1 (a) and (b) are a cross-sectional view and a side view showing an embodiment of a heating wire according to the present invention, and FIG. 2 is an embodiment of a snow-melting electric wire according to the present invention. 3 (a) and 3 (b) are cross-sectional views showing another embodiment. 1: heating wire, 2: ferromagnetic core wire, 3: ridge, 4 aluminum coating, 5: snow melting wire, 6: steel wire, 7: aluminum wire, 8: snow melting wire, 9: steel core aluminum stranded wire.

Claims (2)

(57) [Claims] A helical ridge made of a conductive metal is formed on the outer periphery of a core wire made of a ferromagnetic material such that the cross-sectional area of the ridge of the conductive metal is larger than the cross-sectional area other than the ridge. A heating wire rod characterized by: 2. A snow-melting electric wire, wherein the heat-generating wire according to claim 1 is twisted as an element wire on the outermost layer of the stranded wire conductor or spirally wound around the outer periphery of the stranded wire conductor.