The present invention relates to a power transmission wire heat dissipator wound around an aerial power transmission wire or other power transmission wire for dissipating the heat of the power transmission wire, a power transmission wire (line) equipped with a heat dissipator, and a method for attaching a heat dissipator on a power transmission wire.
It is desired to increase the power transmission capacity of an aerial line (wire).
When the power transmission capacity is increased, the current flowing through the line becomes heated. Therefore, a permissible upper limit is set on the current flowing through the aerial line.
Therefore, the general method of increasing the transmission capacity of an aerial line is use of an aerial line having a larger sectional area.
In the case of an already strung aerial line, the transmission capacity is increased by replacing it with another line having a larger sectional area.
However, a line having a large sectional area becomes heavier in the weight of the line per unit length, so the amount of sagging (sag or slack) becomes larger due to the line""s own weight. If the sag becomes larger, the distance to the ground etc. becomes shorter, so the towers must be made higher and must be made stronger in structure in some cases. Such replacement of towers is difficult in view of on-going operations, work, and costs in many cases. When replacing a tower with one having a higher height and greater strength or fabricating a higher and stronger tower in advance so that a power transmission wire having a larger sectional area will be able to be laid in the future, the problems of a rise of the manufacturing cost of the tower and a rise of the transmission cost are encountered. Also, when the transmission capacity is further increased, the above problem of an increase in the amount of heat generated in the aerial line is still encountered.
As one method of overcoming the problem of the increase of the sag, use has been made of aerial lines made of twisted steel-reinforced aluminum conductors (ACSR)xe2x80x94conductors reinforced by Invar steel wires having a small coefficient of linear expansion and known for low sag. When newly stringing an aerial line made of Invar-reinforced aluminum conductors, the problem of the height of the tower can be overcome since the sag of the ACSR aerial line is small. When trying to increase the transmission capacity of an aerial line made of Invar-reinforced aluminum conductors, however, the number of aluminum conductors has to be increased or the sectional area of the aluminum conductors has to be enlarged. The weight of the aerial line is therefore increased so an excessive load is applied to the tower, and the price of the aerial line becomes remarkably high. Accordingly, the above problem cannot be overcome just by using ACSR for the aerial line.
Further, as one method of overcoming the problem of the large heat generation explained above, use has been made of aerial lines made of thermo-resistant conductors able to withstand high temperature use. For example, if an aerial line made of steel-reinforced ultra thermo-resistant aluminum alloy conductors (UTACSR) is used, usage at a high temperature of 200xc2x0 C. or more is possible. Heating, however, causes the aerial line to elongate. In particular, the increase of the sag of the aerial line at the time of a high temperature cannot be ignored. Therefore, the problem of an increase of the sag is still encountered if just using UTACSR for the aerial line.
Japanese Unexamined Patent Publication (Kokai) No. 64-81110 and Japanese Unexamined Patent Publication (Kokai) No. 64-81111 disclose a technique of covering the outer circumference of the aerial line with a mesh belt so as to prevent the accumulation of snow from causing a tubular mass of snow (snow tubes) from depositing on the outer circumference of the aerial line, increasing the weight of the aerial line, causing sag and in turn breaking the aerial line. However, the technique disclosed in Japanese Unexamined Patent Publication (Kokai) No. 64-81110 and Japanese Unexamined Patent Publication (Kokai) No. 64-81111 is a technique considering only the prevention of tubular accumulation of snow, and not a technique for increasing the transmission capacity of the aerial line. Particularly, Japanese Unexamined Patent Publication (Kokai) No. 64-81110 and Japanese Unexamined Patent Publication (Kokai) No. 64-81111 do not disclose a technique for increasing the transmission capacity of an aerial line by improving the heat dissipation characteristic of the aerial line.
Japanese Unexamined Patent Publication (Kokai) No. 48-72688 (Japanese Unexamined Patent Publication (Kokoku) No. 52-4357) discloses a technique of preventing galloping, which frequently occurs when there is uniform accumulation of ice and snow along a longitudinal direction of the windward side of an aerial line by winding an S-twist and Z-twist helical shaped body having a predetermined length around the outer circumference of the aerial line so that the S-twist and the Z-twist are arranged repeatedly or at random. However, Japanese Unexamined Patent Publication (Kokai) 48-72688 also does not disclose a technique of increasing the transmission capacity of an aerial line by improving the heat dissipation characteristic of the aerial line.
Japanese Unexamined Patent Publication (Kokai) No. 49-101876 (Japanese Examined Patent Publication (Kokai) No. 53-14146) discloses a technique of reducing the noise due to wind pressure on the aerial line by setting the outer diameter of the strands and the outer diameter of the line of a low noise line comprised of strands wound helically or cross-wise and setting the winding pitch to within a predetermined range. However, Japanese Unexamined Patent Publication (Kokai) No. 49-101876 also does not disclose a technique of increasing the transmission capacity of an aerial line by improving the heat dissipation characteristic of the aerial line.
Japanese Unexamined Patent Publication (Kokai) No. 57-98907 (Japanese Examined Patent Publication (Kokoku) No. 58-38884) discloses an aerial line reducing the corona noise of the aerial line by providing a low noise line comprised of a line around the outer circumference of which strands are wound where a plurality of unit strands formed with minute unevenness on the surface of the wound strands are arranged in close contact. However, Japanese Unexamined Patent Publication (Kokai) No. 57-98907 also does not disclose a technique of increasing the transmission capacity of an aerial line by improving the heat dissipation characteristic of the aerial line.
Japanese Unexamined Patent Publication (Kokai) No. 6-302223 discloses reducing the noise due to wind pressure and, further, reducing an AN level by providing a low noise line in which part of the outermost layer of the aerial line is made to project out. However, Japanese Unexamined Patent Publication (Kokai) No. 6-302223 also does not disclose a technique of increasing the transmission capacity of an aerial line by improving the heat dissipation characteristic of the aerial line.
An object of the present invention is to provide a heat dissipator to be attached on a power transmission wire in order to enable an increase of the transmission capacity without an increase of the sectional area of the power transmission wire itself.
Another object of the present invention is to provide a heat dissipator to be attached on a power transmission wire in order to enable an increase of the transmission capacity without an increase of the sectional area of the power transmission wire itself and, further, to enable prevention of accumulation of snow, reduction of noise due to wind pressure, reduction of the corona noise, and prevention of galloping.
Still another object of the present invention is to provide a power transmission wire on which the heat dissipator is attached in order to enable an increase of the transmission capacity without an increase of the sectional area of the power transmission wire itself.
Still another object of the present invention is to provide a power transmission wire on which a heat dissipator is attached in order to enable an increase of the transmission capacity without an increase of the sectional area of the power transmission wire itself and, further, to enable prevention of accumulation of snow, reduction of noise due to wind pressure, reduction of the corona noise, and prevention of galloping.
Still another object of the present invention is to provide a method of attaching such a heat dissipator on a power transmission wire.
According to a first aspect of the present invention, there is provided a heat dissipator for a power transmission wire comprised of a conductive heat dissipation member having conductivity and having a surface heat dissipation rate of 0.7 or more spirally wound around the outer circumferential surface of the power transmission wire at a predetermined winding pitch in close contact thereto.
Preferably, the conductive heat dissipation member is treated to blacken its surface and delustered.
Further preferably, the surface of the conductive heat dissipation member is treated to make it hydrophilic.
Also, preferably, the conductive heat dissipation member has a surface which is artificially or naturally aged in advance.
Preferably, the conductive heat dissipation member is produced by aluminum or an aluminum alloy.
According to the first aspect, the conductive heat dissipation member of the heat dissipator for a power transmission wire has a braided heat conducting wire heat dissipating belt comprised of heat conducting metal strands braided in the form of a mesh belt, the braided heat conducting wire heat dissipating belt being spirally wound around the outer circumferential surface of the power transmission wire at a predetermined winding pitch.
In the first aspect, preferably, the braided heat conducting wire heat dissipating belt has a winding pitch giving a center angle xcex8 of the winding width on the circumference of the cross-section of the power transmission wire with the center of the power transmission wire defined by the following relation:
15xc2x0xe2x89xa6xcex8xe2x89xa6180xc2x0
In the first aspect, preferably, the winding pitch p of the braided heat conducting wire heat dissipating belt around the power transmission wire is set within the following range with respect to an outer diameter D of the power transmission wire:
10Dxe2x89xa6pxe2x89xa630D
In the first aspect, preferably, a spiral rod is wound on the braided heat conducting wire heat dissipating belt wound around the outer circumferential surface of the power transmission wire in a reverse direction to the winding direction of the braided heat conducting wire heat dissipating belt to secure the winding of the braided heat conducting wire heat dissipating belt.
In the first aspect, preferably, the heat conducting metal strand of the braided heat conducting wire heat dissipating belt is a wire made of aluminum or an aluminum alloy having a diameter of 0.3 mm to 3.0 mm.
In the first aspect, preferably, a plurality of the braided heat conducting wire heat dissipating belts are wound around the outer circumferential surface of the power transmission wire in the same direction or so as to cross.
In the first aspect, preferably, an end of the braided heat conducting wire heat dissipating belt wound around the outer circumferential surface of the power transmission wire is wound around a front end of an anchor clamp to secure it.
In the first aspect, preferably, a braided heat conducting wire heat dissipating belt comprised of a heat conducting metal strand braided in the form of a mesh belt is wound around the outer circumference of a jumper at a tension support of the power transmission wire, and the end of the braided belt member is wound around the front end of a jumper connection of the anchor clamp to secure it.
According to a second form of the first aspect of the present invention, the conductive heat dissipation member of the heat dissipator for a power transmission wire has a conductive, surface-blackened heat dissipating spiral rod having a surface heat dissipation rate of 0.7 or more spirally formed in the longitudinal direction so that it can be attached on the outer circumferential surface of the power transmission wire in close contact thereto and the spiral rod is spirally wound around the outer circumferential surface of the power transmission wire at a predetermined winding pitch.
In the second form of the first aspect of the present invention, preferably, the winding pitch p of the surface-blackened heat dissipating spiral rod is set within the following range with respect to the outer diameter D of the power transmission wire:
10Dxe2x89xa6pxe2x89xa630D
In the second form of the first aspect of the present invention, preferably, the surface-blackened heat dissipating spiral rod to wound around the outer circumferential surface of a jumper at the tension support of the power transmission wire.
According to a third form of the first aspect of the present invention, preferably, a conductive heat dissipation member of the heat dissipator for a power transmission wire has a surface-blackened conductive heat dissipation member which is flexible, electrically conductive, and has a surface heat dissipation rate of 0.7 or more to be attached on the outer circumferential surface of the power transmission wire in close contact thereto, and the conductive heat dissipation member is spirally wound around the outer circumferential surface of the power transmission wire at a predetermined winding pitch.
In the third form of the first aspect of the present invention, preferably, when the strand diameter of the outermost layer of the power transmission wire is dd, the outer diameter of the surface-blackened conductive heat dissipation member or the thickness in the diameter direction is DD, the pitch of the twist of the strand of the outer layer of the power transmission wire is pp, and the winding pitch of the conductive heat dissipation member around the outer circumferential surface of the power transmission wire is PP, the following relations stand:
0.8xe2x89xa6DD/ddxe2x89xa62.0,
and
0.8xe2x89xa6PP/ppxe2x89xa65.0
In the third form of the first aspect of the present invention, preferably, when the strand diameter of the outermost layer of the power transmission wire is dd, the outer diameter of the surface-blackened conductive heat dissipation member or the thickness of the diameter direction is DD, the pitch of the twist of the strand of the outer layer of the power transmission wire is pp, and the winding pitch of the conductive heat dissipation member around the outer circumferential surface of the power transmission wire is PP, the following relations stand:
1.0xe2x89xa6DD/ddxe2x89xa61.2,
and
1.0xe2x89xa6PP/ppxe2x89xa62.0
In the third form of the first aspect of the present invention, preferably, (1) the cross-section of the conductive heat dissipating member is circular, (2) the cross-section of the conductive heat dissipating member is a partially fan-like segment, (3) the cross-section of the conductive heat dissipating member is a hollow circle, or (4) the cross-section of the conductive heat dissipating member is a hollow oval.
In the third form of the first aspect of the present invention, preferably, a groove for suppressing the formation of drops of water is formed along the circumference of the conductive heat dissipating member having a circular cross-section.
In the third form of the first aspect of the present invention, preferably, the winding pitch p of the surface-blackened heat dissipating spiral rod around the power transmission wire is set to the following range with respect to the outer diameter D of the power transmission wire:
10Dxe2x89xa6pxe2x89xa630D
In the third form of the first aspect of the present invention, preferably, the surface-blackened heat dissipating spiral rod to wound around the outer circumferential surface of the jumper at a tension support of the power transmission wire.
According to a second aspect of the present invention, there is provided a power transmission wire having a heat dissipating means comprised of a conductive heat dissipation member having conductivity and a surface heat dissipation rate of 0.7 or more spirally wound around the outer circumferential surface at a predetermined winding pitch in close contact thereto.
Preferably, the conductive heat dissipation member is treated to blacken its surface and delustered.
Further, preferably, the surface of the conductive heat dissipation member is treated to make it hydrophilic.
Further, preferably, the conductive heat dissipation member has a surface which is artificially or naturally aged in advance.
Preferably, the conductive heat dissipation member is produced from aluminum or an aluminum alloy.
Preferably, the power transmission wire is produced from any of steel-reinforced aluminum conductors (ACSR), steel-reinforced ultra thermo-resistant aluminum alloy conductors (UTACSR), Invar-reinforced super or extra thermo-resistant aluminum alloy conductors (ZTACIR or XTACIR), and galvanized steel twisted wire.
Preferably, the conductive heat dissipation member is a braided heat conducting wire heat dissipating belt comprised of a heat conducting metal strand braided in the form of a mesh belt.
Preferably, a plurality of braided heat conducting wire heat dissipating-belts are wound around the outer circumferential surface of the power transmission wire in close contact thereto in the same direction or so as to cross.
Further, preferably, the conductive heat dissipation member is a conductive, surface-blackened heat dissipating spiral rod having a surface heat dissipation rate of 0.7 or more formed spirally in the longitudinal direction so that it can be attached to the outer circumferential surface of the power transmission wire in close contact thereto.
Further, preferably, the conductive heat dissipation member is a surface-blackened conductive heat dissipation member which is flexible, electrically conductive, and has a surface heat dissipation rate of 0.7 or more to be attached on the outer circumferential surface of the power transmission wire in close contact thereto.
According to a third aspect of the present invention, there provided a method of attaching a heat dissipator on a power transmission wire comprising spirally winding a heat dissipation member having conductivity and a surface heat dissipation rate of 0.7 or more around the outer circumferential surface of an aerial line in close contact thereto at a predetermined winding pitch.
Preferably, the attachment work is carried out while transmitting power through the power transmission wire.
Preferably, the conductive heat dissipation member is produced from aluminum or an aluminum alloy.
Preferably, the conductive heat dissipation member is a braided heat conducting wire heat dissipating belt comprised of a heat conducting metal strand braided in the form of a mesh belt.
Preferably, the braided heat conducting wire heat dissipating belt has a winding pitch giving a center angle xcex8 of the winding width on the circumference of the cross-section of the power transmission wire with the center of the power transmission wire defined by the following relation:
15xc2x0xe2x89xa6xcex8xe2x89xa6180xc2x0
Further, preferably, the winding pitch p of the braided heat conducting wire heat dissipating belt around the power transmission wire is set within the following range with respect to an outer diameter D of the power transmission wire:
10Dxe2x89xa6pxe2x89xa630D
Further, preferably, a plurality of the braided heat conducting wire heat dissipating belts are wound around the outer circumferential surface of the power transmission wire in the same direction or so as to cross.
Further, preferably, the conductive heat dissipation member is a conductive, surface-blackened heat dissipating spiral rod having a surface heat dissipation rate of 0.7 or more spirally formed in the longitudinal direction so that it can be attached to the outer circumferential surface of the power transmission wire in close contact thereto.
Preferably, the winding pitch p of the surface-blackened heat dissipating spiral rod around the power transmission wire is set to the following range with respect to the outer diameter D of the power transmission wire:
10Dxe2x89xa6pxe2x89xa630D
Further, preferably, the conductive heat dissipation member is a surfaoe-blackened heat dissipating spiral rod which is flexible, electrically conductive, and has a surface heat dissipation rate of 0.7 or more to be attached at the outer circumferential surface of the power transmission wire in close contact thereto.
Preferably, when the strand diameter of the outermost layer of the power transmission wire is dd, the outer diameter of the surface-blackened conductive heat dissipation member or the thickness of the diameter direction is DD, the pitch of the twist of the strand of the outer layer of the power transmission wire is pp, and the winding pitch of the conductive heat dissipation member around the outer circumferential surface of the power transmission wire is PP, the following relations stand:
0.8xe2x89xa6DD/ddxe2x89xa62.0,
and
0.8xe2x89xa6PP/ppxe2x89xa65.0
Further, preferably, when the strand diameter of the outermost layer of the power transmission wire is dd, the outer diameter of the surface-blackened conductive heat dissipation member or the thickness of the diameter direction is DD, the pitch of the twist of the strand of the outer layer of the power transmission wire is pp, and the winding pitch of the conductive heat dissipation member around the outer circumferential surface of the power transmission wire is PP, the following relations stand:
1.0xe2x89xa6DD/ddxe2x89xa61.2,
and
1.0xe2x89xa6PP/ppxe2x89xa62.0