JPH0449723B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a magnetic wire, particularly a magnetic wire for aluminum power transmission lines, which is used by being wound around electric wires to prevent water condensation on overhead power transmission and distribution lines. During the winter, in cold regions, especially in northern Japan and the back of Japan, snow and ice accumulate on overhead power lines, and this grows to a considerable size, leading to an increase in the weight of the wires in the span and an increase in the wind pressure load. This often leads to accidents such as an increase in the slackness of the wires, breakage of the wires due to excessive tension, and even the collapse of the steel tower. In addition, when ice and snow fall in the form of blocks, it poses a danger to people passing under the overhead wires, and even if the area under the overhead wires is farmland, it can cause damage to crops, vinyl houses, etc., and is a major social problem. occurs, so a solution to this problem is desired. For this reason, as a measure to prevent snow accumulation, methods have been used to prevent snow buildup, such as temporarily transmitting large currents to melt the snow due to the heat of the conductor, or attaching ring-shaped objects to power transmission lines to cause the snow to fall. However, large current transmission is not possible freely due to restrictions on power system operation, and even if a ring-shaped device is installed, the effectiveness varies depending on the type of ice and snow, and the problem has grown further. If ice and snow blocks are simply allowed to fall, there is a risk of secondary disasters occurring at the point where they fall, and this cannot be said to be a sufficient countermeasure. On the other hand, sleeves made of magnetic material, linear bodies processed into a spiral shape, tapes,
A method has also been proposed in which snow is melted using heat loss due to hysteresis loss and eddy current loss generated when the alternating current magnetic field generated by the transmitted current passes through the sleeve, etc., by winding it around a rod, etc. Wrapping wires, tapes, and rods around electric wires increases the weight of the wires, so it is desirable that they be as light as possible, and heat generated by magnetic materials at temperatures that do not cause icing or snow increases power transmission losses. So,
It is desirable to use a material with a low Curie point, which reduces its magnetic properties and does not generate heat at high temperatures. So-called low-Kyrie point materials, which have a Kyrie point near room temperature, are generally characterized by having a smaller retention force than materials with a higher Kyrie point. Therefore, the desired snow melting effect cannot be expected only with hysteresis loss related to heat generation, and it is necessary to use heat generation due to eddy current loss in combination. When the Curie point of the magnetic material is high (300°C or higher), the heat generated by hysteresis loss is larger than the heat generated by eddy current loss, so changing the thickness of the coating material does not make much of a difference. However, when the Curie point becomes low (below 200°C), the heat generated by eddy current becomes larger than the heat generated by hysteresis loss, so if the thickness of the highly conductive metal coating layer is not determined to an appropriate size, snow melting effects will not be observed. This may cause problems such as not being able to do so. As a result of various studies, the present inventors discovered that
When a Ni, Cr, Si, Fe-based alloy with a Cr content of 3.1% by weight or less is coated with an aluminum alloy-based low-resistance material around a wire rod having a circular cross section, the thickness of the coating material is To provide a magnetic wire having a circular cross section, in which the area ratio of the cross-sectional area occupied by the conductive material to the total cross-sectional area is 15 to 40%, and even more preferably 20 to 30%. . Here, the Cr content was set to 3.1% by weight or less because Cr
This is because a significantly more advantageous heat generation effect can be obtained compared to alloys with a Cr content of more than 3.1% by weight. Furthermore, when the area ratio of the highly conductive material made of the alloy used in the present invention is less than 15%, the effect of coating with the conductive material is too small, and it seems that it is particularly effective when the area ratio is 20% or more. be. Furthermore, if the conductive material is coated with a thickness exceeding 40%, heat generation will be reduced, which is inappropriate. Further, in the present invention, since a wire rod having a circular cross section is selected, the coating thickness is uniform, and even when subjected to strain relief processing, a wire rod having a uniform thickness can be obtained, and a wire rod with good heat generation characteristics can be provided. The present invention will be described below with reference to Examples. Examples 1 and 2 Ni36% by weight, Cr3.1% by weight, Si1.0% by weight, balance
Alloy consisting of Fe (Example 1), Ni 36% by weight,
An alloy (Example 2) consisting of 0.5% by weight of Cr, 1.0% by weight of Si, and the balance of Fe (Example 2) was vacuum melted and cast into a mold with a diameter of 30 mm. After processing these alloys into wires with a diameter of 10 mm by cold casting and wire drawing, the alloy surface is polished and coated with aluminum tubes with a thickness of 0.3 to 2.0 mm, and then various sizes of wires with a diameter of 2.4 to 3.0 mm are formed. The wire was drawn so that the diameter of each core material was 2.3 mm. The aluminum coverage of each wire is 10~49
%. Comparative Examples 1 and 2 Same as Example 1, but the aluminum tube was drawn to a diameter of 2.3 mm without coating (Comparative Example 1), and the final wire diameter was galvanized (Comparative Example 2). . For these Examples and Comparative Examples, the amount of heat generated in an alternating magnetic field of 300e was measured. This is shown in FIG. The amount of heat required for snow melting is 300e per 1kg due to the weight limit of the magnetic wire attached to the electric wire.
Since approximately 30 watt or more is required, it has been found that sufficient heat generation for practical use can be obtained with an area ratio of 15 to 40%. Examples 3 and 4 Ni36% by weight, Cr3.1% by weight, Si1.0% by weight, balance
An alloy wire with a circular cross section made of Fe (Example 3), and
Hard steel wire with circular cross section specified by JIS G 3506
A composite wire was manufactured by coating each steel wire (Example 4) made of SWRH 62 A with electrical aluminum so that the area ratio was 25%. Comparative Examples 3 and 4 Comparative Examples 3 and 4 were prepared by using the same alloy wire and hard steel wire as in Examples 3 and 4 without applying aluminum coating, respectively. For each of the samples of Examples 3 and 4 and Comparative Examples 3 and 4, the heat generation at 0°C was measured under alternating magnetic fields of 50 0e and 150e. Table 1 shows the calorific value per 1 kg of sample weight. Note that wire rods that have been subjected to residual strain removal processing by roller processing or the like after wire drawing naturally exhibit toughness and also have a large calorific value, so they can be provided as more preferable wire rods. Figure 1 shows the relationship between aluminum area ratio and calorific value for various types of aluminum alloys [those with Cr content of 3.1% by weight, 0.5% by weight (both the present invention) and 5% by weight (comparative example)]. From this graph, it can be seen that the product of the present invention is superior.

[Table] As can be seen from this table, in the case of hard steel wires, there is not much difference regardless of whether they are coated or not, and the loss increases which is unnecessary for practical purposes. In the case of alloy wires, those coated with aluminum generate about four times as much heat as those without aluminum coating, and even when the magnetic field increases, the increase in heat generation is not that large; It can be seen that alloy coating is essential.

[Brief explanation of the drawing]

Figure 1 is a graph of the Al area ratio (%) and calorific value per 1 kg (Watt/Kg) of aluminum tube-coated magnetic wire. It is.

Claims (1)

[Scope of Claims] 1. A highly conductive aluminum-based metallic material coating layer having a uniform thickness on the entire circumferential surface of a magnetic wire material having a circular cross section and made of a Ni, Cr, Si.Fe-based alloy with a Cr content of 3.1% by weight or less. A magnetic wire with a circular cross section, characterized in that the total cross-sectional area ratio is 15 to 40%. 2. The magnetic wire according to claim 1, wherein the wire is subjected to strain relief processing after wire drawing.