JPH0447538B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for cooling power transmission lines buried underground.

(Prior art and its problems) Conventionally, as shown in Figures 5 and 6, cables for underground power transmission have been made using core wires a as conductors.
A structure is used in which two or three of the insulators covered with insulator b are stored in a sheath tube c in a bundle, and the space between the sheath tube c and insulator b is filled with insulating oil d. ing.

When such a cable is energized, heat is generated due to the resistance of the core wire, and this heat is conducted to the insulator b, the insulating oil d, and the sheath tube c, and is naturally radiated to the outside air.

However, since cables are routed inside underground pipes, the external space around the cables does not move, so heat accumulates inside the underground pipes.
If the amount of heat stored is larger than the amount of heat radiated, there is a risk that the insulator etc. will be damaged, so the heat must be radiated by appropriate means, but in the conventional technology, this heat is transferred from the underground pipe to the ground. The current situation is to dissipate it by absorbing it.

Therefore, the allowable amount of heat generated from the core wire a is determined by the heat absorption capacity of the ground, and the electrical capacity that conducts electricity through the core wire a is also limited by the heat absorption capacity of the ground. When doing so, a problem arises in that the amount of power transmitted must be suppressed or the core wire a must be made thicker so as not to increase the amount of heat generated.

For this reason, there are methods to directly or indirectly cool the cables by circulating cooling water through the underground pipes that house the cables, or by installing cooling water pipes in parallel along the cable pipes. However, not only is the work of laying multiple cable installation pipes complicated, but it is also difficult to install each cable installation pipe.
Alternatively, separate cooling water supply and discharge pipes are required for the cooling water pipes installed in parallel with the installed pipes, which not only increases the construction cost but also requires time and effort. Furthermore, in the case of indirect cooling, the cooling efficiency is poor, and even in direct cooling, the conventional method uses two cable laying pipes as a set, and one cable laying pipe is used as the supply pipe.
The other cable installation pipe is used as the discharge pipe, and the cooling water used to cool the cable after passing through the supply pipe is returned to the discharge pipe to perform the cooling action again, so the discharge pipe There was a problem in that efficient cooling could not be performed on the roadside.

The present invention provides a method for cooling underground power transmission lines aimed at solving these problems.

(Means for Solving the Problems) In order to achieve the above object, the underground power transmission line cooling method of the present invention includes a plurality of small diameter cable installation holes around a central hole extending between both end faces. A perforated underground pipe is laid underground between the manholes, and the open end face of the hollow box is placed on the outer periphery of both end faces of the perforated underground pipe exposed to these manholes. The power transmission line inserted into the small-diameter cable installation hole of the multi-hole buried pipe is tightly fixed and introduced into the manhole in a watertight manner from inside both hollow boxes, and the cooling fluid supply pipe is inserted into one hollow box. At the same time, a return pipe is connected to the central hole between the holes opened in the hollow box, and a cooling fluid is circulated from inside the hollow box to each small diameter cable installation hole to connect and communicate with the other hollow box. It is characterized in that the liquid is allowed to flow out into the box and then flowed from the hollow box into the return pipe through the central hole of the porous buried pipe.

(Function) Power transmission lines inserted and routed through the multiple small-diameter cable installation holes penetrating the outer periphery of the multi-hole buried pipe are forcibly cooled by the cooling fluid flowing through these holes. The heat dissipated from the core wire can be absorbed by the cooling fluid, which not only prevents deterioration of the insulating oil and damage to the insulator due to heat generation, but also prevents large currents from flowing through the core wire. It is possible.

Furthermore, the cooling water fluid, whose temperature has increased by absorbing heat generated from the core wire, joins in the other hollow box and is discharged to the outside through the return pipe from the hollow hole of the multi-hole buried pipe, and the high temperature fluid is separated. In addition, if insulating oil is used as the cooling fluid, there is no need to use cables with built-in insulating oil as in the past for underground wiring. Wiring cables can be provided at low cost.

(Embodiment) Next, an embodiment of the present invention will be explained with reference to the drawings. Reference numerals 1 and 2 are manholes formed by digging in the ground at appropriate intervals, and there is concrete between these adjacent manholes 1 and 2. A multi-hole buried pipe 3 is buried in a penetrating state, and the buried pipe 3 faces the manholes 1 and 2.
The open end surfaces of the hollow boxes 4 and 5 are closely and firmly fixed to the outer peripheral edges of both end surfaces of the hollow boxes 4 and 5.
Both end surfaces of the buried pipe 3 are hermetically covered.

As shown in FIG. 2, the porous buried pipe 3 has a plurality of (six in the figure) small-diameter cable installation holes 7, 7, . A power transmission cable 8 is inserted into these cable installation holes 7, and both ends of the power transmission cable 8 penetrate through the hollow boxes 4 and 5 in a water-tight manner via water-stop packing 9, and are connected to the adjacent Connect the power transmission cable 8 of the buried pipe 3 and the coupler 1 in the manholes 4 and 5.
It is connected via 0.

As shown in FIGS. 5 and 6, the power transmission cable 8 consists of two to three conductor core wires a covered with an insulator b, which are stored in a bundle in a sheath tube c. Insulating oil d in the space between pipe c and insulator b
It has a structure filled with

Furthermore, cooling fluid supply pipes 11 and return pipes 12 are arranged from appropriate locations on the ground into each manhole 1 and 2,
The supply pipe 11 is communicated with one of the hollow boxes 4 via the pump 13, while the return pipe 12 penetrates the hollow box 4 in a watertight manner and its open end is connected to the open end of the central hole 6 of the buried pipe 3. They are connected and communicated.

With this configuration, when a cooling fluid such as cooling water is pumped from the supply pipe 11 into the hollow box 4 by the pump 13 while power is being transmitted to the power transmission cable 8, the cooling fluid is transferred from the hollow box 4 to the buried pipe. A distribution path is taken in which the cables flow through each cable installation hole 7 of the pipe 3, flow into the other hollow box 5, flow from this hollow box 5 through the central hole 6, flow into the return pipe 12, and are sent out to the outside. .

In such a flow state, while passing through the cable installation hole 7, the cooling fluid directly cools the sheath tube c of the power transmission cable 8 installed in the hole 7, and the core wire of the power transmission cable 8 absorbs heat radiated from a. The cooling fluid that has become high temperature by absorbing this heat is sent out from the return pipe 12 as described above.
The high-temperature fluid is used for heating, etc.

In this case, the supply pipe 11 and the return pipe 12 are connected,
By communicating with the pump 13 and circulating the sealed path, the temperature of the cooling fluid can be further increased, and while this high temperature fluid is taken out from the return pipe 12 to an appropriate amount, the amount corresponding to the amount taken out is also increased. What is necessary is to send new cooling fluid into the supply pipe 11.

In addition, the power transmission cable 8 is directly cooled by circulating the cooling fluid through the cable installation hole 7;
In addition to this cooling method, the porous buried pipe itself may also be forcibly cooled.

As shown in FIG. 3, the buried pipes 3 used in such a cooling method include cable installation holes 7
A pipe is used in which a water supply hole 20 is inserted through the buried pipe in the vicinity of the pipe, and a supply pipe 11 is connected and communicated with one end opening of these water supply holes 20 to cool the buried pipe main body, and from the power transmission cable 8. What is necessary is to absorb the heat that is generated and accumulated in the buried pipe body.

FIG. 4 shows another embodiment of the invention, in which insulating oil is used as the cooling fluid.

That is, as in the above embodiment, the adjacent manholes 1,
burying the underground pipe 3 underground between the two, and inserting the power transmission cable 8 into the cable installation hole 7 of the buried pipe 3;
A supply pipe 11 equipped with a pump 13 is connected and communicated with the hollow box 4 of one manhole 1, and a return pipe 12 is connected to the opening at one end of the central hole 6 of the buried pipe.
In this structure, a heat exchanger 14 is installed in the manhole 1 or at an appropriate location on the ground, and the supply pipe 11 and the return pipe 12 are connected through a heat exchange pipe 15 in the heat exchanger 14. Furthermore, a water introduction pipe 16 and a pump 17 are connected to the heat exchanger 14 in an endless manner.
The hot water outlet pipe 18 is connected to the hot water outlet pipe 18.

With this configuration, when the pump 13 is driven while the hollow boxes 4 and 5, the supply pipe 11, and the return pipe 12 are filled with insulating oil from the buried pipe 3, the insulating oil will flow from the hollow box 4. It flows through each cable installation hole 7 of the buried pipe 3, flows from the other hollow box 5 through the central hole 6, return pipe 12, and heat exchanger 14, and flows back to the supply pipe 11 for circulation.

Then, the insulating oil absorbs heat from the power transmission cable 8 while flowing through the cable installation hole 7, and the heat exchanger 14
The temperature of the water inside is increased to make it warmer, while the insulating oil is cooled.

By driving this hot water pump 17, the water can be taken out and used as appropriate.

Since the insulating oil is made to flow through the cable installation hole 7 in this way, it is possible to use a cable that is not coated with an insulator as the power transmission cable 8 that distributes power into the installation hole 7. It is possible.

In the above embodiment, the cooling fluid was circulated in the buried pipe 3 buried between the adjacent manholes 1 and 2, but the present invention does not require such a circulation means and the cooling fluid is Buried pipe 3, 3...
The cooling fluid may be configured to flow back into the cooling fluid.

(Effects of the Invention) As described above, according to the underground power transmission line cooling method of the present invention, a plurality of small-diameter cable installation holes are formed around the central hole and penetrate between both end faces. Since the underground pipes are laid underground between the manholes, wiring work can be easily done by simply inserting the power lines into the multiple small-diameter cable installation holes mentioned above. In addition, the open end surface of the hollow box is closely fixed to the outer periphery of both end surfaces of the porous buried pipe exposed in both holes, and the above-mentioned power transmission line inserted into the small diameter cable installation hole of the porous buried pipe is inserted into both hollow holes. A cooling fluid supply pipe is connected and communicated with one of the hollow boxes, and a return pipe is inserted into the center hole of the multi-hole buried pipe that opens into the hollow box. After connecting, the cooling fluid flows from inside the hollow box to each small diameter cable installation hole and flows out into the other hollow box, and then flows from the hollow box into the return pipe through the central hole of the multi-hole buried pipe. Since the cooling fluid is made to flow out, by supplying the cooling fluid from the supply pipe into one hollow box, the cooling fluid can be distributed all at once to multiple small-diameter cable installation holes, making it easy to use. The power transmission lines inserted into each of the small-diameter cable installation holes can be forcibly and efficiently directly cooled by the flow path.

Furthermore, the fluid used to cool the power transmission lines is combined in the other hollow box and discharged from the hollow hole of the multi-hole buried pipe to the outside through the return pipe, so the temperature increases due to the cooling of multiple power transmission lines. The fluid can be collected in the central hole of the multi-hole buried pipe and led out without adversely affecting the low-temperature cooling water flowing through the small-diameter cable.Furthermore, the fluid can be discharged from the central hole through a single return pipe. The heated fluid can be easily and efficiently used as bath water, hotbed water, etc.

Furthermore, if insulating oil is used as the cooling fluid, there is no need to use cables with built-in insulating oil as in the past for underground wiring, and therefore underground wiring cables can be provided at low cost. I can do it.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a simplified vertical side view thereof, FIG. 2 is a vertical front view of a buried pipe, FIG. 3 is a sectional view showing another shape of the buried pipe, and FIG. The figure is a simplified vertical sectional side view showing another embodiment of the present invention, and FIGS. 5 and 6 are sectional views of a power transmission cable. 1, 2... Person hole, 3... Buried pipe, 6... Center hole, 7... Cable installation hole, 8... Power transmission cable, 11... Supply pipe, 13... Return pipe.

Claims (1)

[Claims] 1. A perforated underground pipe with multiple small-diameter cable installation holes penetrating between both end faces around the central hole is laid underground between the manholes, and these The open end surface of the hollow box is closely fixed to the outer periphery of both end surfaces of the porous buried pipe exposed to the manhole,
The power transmission line inserted into the small-diameter cable installation hole of the multi-hole buried pipe is watertightly introduced into the manhole from inside both hollow boxes, and a cooling fluid supply pipe is connected and communicated with one of the hollow boxes. At the same time, a return pipe is connected to the center hole of the multi-hole buried pipe opening into the hollow box, and the cooling fluid is caused to flow from inside the hollow box to each small diameter cable installation hole and flow out into the other hollow box. A method for cooling an underground power transmission line, characterized in that the water is then allowed to flow from the hollow box into the return pipe through the central hole of the multi-hole buried pipe.