JPS6353769B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a cooling device for efficiently cooling the heat of a power cable generated by energization using a refrigerant.

It is well known that when power is transmitted through a power cable, the temperature of the cable increases as a result of Joule loss occurring in the conductor, dielectric loss occurring in the dielectric material, and circuit loss and eddy current loss occurring in the metal sheath.

However, recently, in order to increase the power transmission capacity of power cables, various types of forced cooling have been applied to increase the current value. When such a forced cooling line is installed in a tunnel, the cable and the cooling water pipe can coexist in the cable storage trough, and the cable can be reliably cooled. Furthermore, when installing a pipe, the cable can be reliably cooled by filling the space between the pipe and the cable with cooling water.

However, in areas where the power cable is bent and expands and contracts, such as at the offset part in the manhole or at the bottom of the cable termination box, it is not possible to construct a standard cross section with cooling, and these areas become hot spots. Cooling means will be required. For this reason,
A method of attaching heat dissipation fins to a power cable as in JP-A-49-119173, and a method of attaching multiple cooling pipes vertically to a power cable at an offset section as in JP-A-49-119172 have been proposed. ing. However, among these methods, the former has only the effect of natural cooling of the heat dissipation fins, and the cooling effect may not be sufficient. Also, the latter has a large number of cooling pipes,
The piping for water supply is complicated and expensive, and the pipes must be bent individually according to the shape of the offset section, which is quite difficult to do manually and has poor workability, so installation requires a lot of effort. The problem is that it takes time. Also, even in thin power cables where the bending stiffness of the pipe does not need to govern the movement of the offset section, the pipe may undesirably restrict the natural movement of the cable. Also, when supporting power cables with insulators, etc.
The drawback is that the cooling pipe gets in the way and the support method is difficult.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to simplify the present invention by providing a cooling pipe and a band-shaped heat transfer tentacle in contact with the cooling pipe and the belt-shaped heat transfer tentacles in continuous or partial surface contact with the surface of the power cable. It is an object of the present invention to provide a structure of a power cable hot spot cooling device that has a simple structure, good workability, low cost, and high cooling efficiency.

The present invention provides a cooling pipe attached vertically to the surface of a power cable, and a band-shaped transmission cable that covers at least a part of the surface of the cooling pipe and at least a part of the surface of the power cable and brings them into surface contact in the length direction. 1 is a power cable hot spot cooling device characterized by comprising a thermal tentacle.

Hereinafter, the present invention will be explained by examples using the drawings. FIG. 1 is a cross-sectional view showing a portion of an embodiment of the cooling device of the present invention attached to an OF cable. In the figure, 1 is a stranded conductor having an oil passage 2 in the center, and its outer periphery is covered with an insulating layer 3, an aluminum sheath 4, and an anticorrosion layer 5 made of polyethylene, polyvinyl chloride, or the like. When such a power cable is energized, heat is generated in the stranded conductor 1 and its outer layers 3, 4, and 5 due to Joule loss, dielectric loss, and sheath loss, and this heat is sequentially transferred toward the outer surface. Heat is radiated from the anti-corrosion layer 5 to the outside. In order to effectively absorb this heat, a cooling device 6 is provided in the present invention.

The cooling device 6 includes a cooling pipe 7 attached vertically to the surface of the anti-corrosion layer 5 of the power cable, and covers about half of the outer circumference of the cooling pipe 7 and about half of the surface of the anti-corrosion layer 5. Band-shaped heat transfer tentacles in surface contact 8
Further, thereon, an exterior putty 9 such as soft epoxy putty is adhered from the outside to prevent rust, protection, and peeling of the cooling pipe 7 and band-shaped heat transfer tentacle 8. cooling pipe 7
may be a metal tube made of copper, aluminum, stainless steel or the like, or a plastic tube such as polyethylene, in which a refrigerant 10 such as water or oil is circulated. The band-shaped heat transfer tentacle 8 is formed from a metal ribbon made of, for example, copper, brass, aluminum, stainless steel, etc., and the parts of the cooling pipe 7 and the power cable covered by it are at least part of their surfaces. Yes, or all of them. As shown in the figure, by covering about half the circumference of the surface of the cooling pipe 7 and about half the circumference of the anticorrosion layer 5, molding and installation are easy, and calculation results show that a sufficient cooling effect can be obtained. Exterior putty 9 for protecting the band-shaped heat transfer tentacle 8 is not necessarily required, and instead of putty, it is possible to simply apply paint for rust prevention.

In order to attach such a cooling device 6 to a power cable, for example, a large number of band-shaped heat transfer tentacles 8 with a width of 20 to 30 mm are fixed in advance to the cooling pipe 7 by soldering or brazing, and then a layer of exterior putty 9 is applied. The device can be assembled by assembling the parts in advance, placing them along the length of the outer surface of the power cable, and bonding the heat transfer tentacle 8 part to the outer surface of the cable with adhesive. Alternatively, the forming of the band-shaped heat transfer tentacle 8, the attachment of each part, and the assembly may all be carried out manually on site.

The cooling device of the present invention configured as described above has a good heat absorption effect due to the effect of the heat transfer tentacles, so it can be sufficiently cooled by using only one cooling pipe. In addition to easy piping such as valve installation, the structure is simple and work is easy, the space around the power cable is minimized, and it is easy to adjust to the individual curvature of the cable, which improves workability. It has the advantage of good performance and can be manufactured at low cost. Further, in the cooling device of the present invention, a cooling pipe is attached vertically to the surface of the power cable, and the band-shaped heat transfer tentacle covers at least a part of the surface of the cooling pipe and at least a part of the surface of the power cable. Since the cable is in direct surface contact, the heat generated by the cable can be effectively collected by the band-shaped heat transfer tentacles and transferred to the refrigerant in the cooling pipe, and heat is dissipated with high cooling efficiency. It has the effect of ensuring sufficient cooling effect, effectively preventing the temperature rise of the power cable, and significantly improving the power transmission capacity.

Figure 2 shows the installed embodiment of the cooling device of the present invention.
This is a diagram showing isothermal lines in the cable cross section as a result of thermal analysis of a single-core OF cable with a conductor cross section of 275 kV and a conductor cross section of 2500 mm ^2. The vertical axis is the diametric distance passing through the center of the cooling pipe in the cable cross section. , the horizontal axis indicates the distance perpendicular to this diameter direction. The figure shows the results of computer analysis for determining the isothermal line within the cross section of the cable in order to confirm the effects of the present invention. The input conditions were to use a single cooling pipe with a diameter of 30 mm and a band-shaped heat transfer tentacle, and to increase the temperature of the cooling water to 30
℃, and the outside temperature was 40℃.

In Figure 2, a cooling device according to the invention is installed.
This shows that the conductor temperature of the OF cable can be suppressed to 67℃.

On the other hand, although not shown in the figure, for comparison, we conducted a similar analysis on the same cable as described above, excluding only the band-shaped heat transfer tentacles, and found that the conductor temperature was
The temperature reached 77℃, indicating that the heat transfer tentacles were useful in reducing the conductor temperature by 10℃.

From the above analysis results, it was confirmed that the cooling device according to the present invention has good cooling efficiency and significantly reduces the temperature rise of the conductor.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a portion of an embodiment of the cooling device of the present invention attached to an OF cable. FIG. 2 is a diagram showing isothermal lines in a cross section of a single-core OF cable to which the cooling device of the present invention is attached. DESCRIPTION OF SYMBOLS 1...Twisted wire conductor, 2...Oil passage, 3...Insulating layer, 4...
Aluminum sheath, 5... Corrosion protection layer, 6... Cooling device, 7... Cooling pipe, 8... Band-shaped heat transfer tentacle, 9... Exterior putty, 10... Refrigerant.

Claims (1)

[Scope of Claims] 1. A cooling pipe attached vertically to the surface of a power cable, and covering at least a part of the surface of the cooling pipe and at least a part of the surface of the power cable, and continuous or partial in the length direction. 1. A hot spot cooling device for a power cable, characterized by comprising a band-shaped heat transfer tentacle in surface contact with each other. 2. The hot spot cooling device for a power cable according to claim 1, wherein the band-shaped heat transfer tentacles are made of metal ribbons or ribs made of copper, brass, aluminum or stainless steel. 3. The power cable hot spot cooling device according to claim 1 or 2, wherein the band-shaped heat transfer tentacle has a coating layer made of exterior putty on its outer surface.