JP5140255B2 - Heat storage material and cooling method for power cable - Google Patents

Description

  The present invention relates to a heat storage material mainly composed of sodium acetate trihydrate and a method for cooling an electric power cable using the heat storage material.

  For example, in a power cable laid in a pipeline, a heat spot where the temperature rises locally tends to be formed at the intersection with the subway, the bridge extension, or near the cable outlet of the substation. Due to the temperature rise of the power cable at the heat spot, the transmission capacity of the entire transmission line may be limited. For this reason, it has been proposed to cool the power cable from the viewpoint of suppressing the temperature rise of the power cable. As conventional techniques related to this, for example, the triplex CV cable described in Patent Document 1 and Patent Document 2 are described. There is an in-pipe power cable cooling system.

JP-A-10-154421 JP 2005-137192 A

  Patent Document 1 discloses a triplex in which a power cable and a heat storage pipe filled with paraffin as a heat storage material are twisted together to reduce an increase in the conductor temperature of the power cable by latent heat of liquefaction of paraffin in the heat storage pipe. A CV cable is disclosed. Patent Document 2 discloses a cooling liquid composed of cooling water and a water-soluble lubricating polymer as a viscosity-increasing filler mixed to increase the viscosity of the cooling water in a pipeline in which a power cable is laid. Is sealed in the pipeline by sealing both ends of the pipeline with stoppers, and the cooling of the power cable in the pipeline that absorbs the heat of the power cable by the enclosed cooling liquid and dissipates it outside the pipeline. A system is disclosed.

  According to Patent Document 1, since a cable in which a power cable and a heat storage pipe are twisted together is used, the power cable and the heat storage pipe are twisted together when applied to an existing pipeline in which the power cable is already installed. There is a problem in that it cannot be easily applied to existing pipelines due to problems such as replacement of existing cables and temporary suspension of power supply accompanying the replacement work. Further, according to Patent Document 2, it is necessary to completely seal both end faces of the pipe line so that the coolant does not leak. In particular, a single-core cable in which cable end movement occurs due to thermal contraction of the cable is installed. There is a problem that it is difficult to apply to the pipe line. In addition, because buoyancy is generated in the power cable due to the coolant filled in the pipe, a location where a cable surfing phenomenon occurs such that the cable moves in one direction due to running vibration of a car or the like on the road Then there is concern that this surfing phenomenon will be promoted.

  Therefore, the present invention provides a heat storage material suitable for cooling the power cable, and a cooling method using the heat storage material, in which the power cable has already been laid without causing the above-described problems. It is an object of the present invention to provide a power cable cooling method that can be easily applied to existing pipe lines.

In the power cable cooling pack member of the present invention , sodium acetate trihydrate as a main component and the sodium acetate trihydrate mixed with the sodium acetate trihydrate so that the sodium acetate trihydrate does not cure even at a temperature below its melting point. is the a liquid additive and the weight ratio of ethylene glycol 10: 2-10: by Rukoto such have an effective ingredient mixed heat storage 5, the which has the flexibility to fluidity even during solidification The heat storage material that has higher thermal conductivity than sodium acetate trihydrate is composed of a two-layer structure of vinyl chloride material and polyethylene material. It is enclosed in a flexible pack member that is slidably in contact with each other, and a string or a rope to be drawn into the heat spot is provided at both ends of the pack member. The vignetting the eyelet, by having, to achieve the above object.

According to such a power cable cooling pack member , since the heat storage material has softness or fluidity even when solidified, it can be easily applied to an existing pipe line, for example, by being sealed in a flexible pack member. It can also be easily applied to power cables laid in troughs and caves. Furthermore, since it has good thermal conductivity, the power cable and the like can be effectively cooled by the thermal conductivity and / or latent heat of fusion.

In the present invention, in the method for cooling a power cable laid in a pipeline, a heat storage material is enclosed in a flexible pack member composed of a two-layer structure of a vinyl chloride material and a polyethylene material , At least one pack member encapsulating the heat storage material is slidably disposed across the heat spot of the power cable in the conduit, and is disposed in the conduit. that the heat storage material, and sodium acetate trihydrate as a main component, from the ethylene glycol sodium acetate trihydrate is mixed with the sodium acetate trihydrate to prevent curing in the temperature below the melting point in it becomes liquid additive and the weight ratio of 10: 2-10: acetate isocyanatomethyl which has by becoming a valid ingredient mixed heat storage 5, the flexible or flowable even during solidification Um trihydrate is configured to have a higher thermal conductivity than a string or rope having through eyelets provided at both ends of the packed member, fixed retracted into the heat spot, the heat storage material The above object is achieved by a method for cooling a power cable, wherein the power cable is cooled by thermal conductivity and / or latent heat.

  According to such a cooling method of the power cable, the power cable in the pipeline is cooled by disposing the flexible pack member in which the heat storage material described above is enclosed in the pipeline. It is not necessary to replace the cable or seal the end face of the pipe, and the present invention can be easily applied to an existing pipe where the power cable is already installed.

  The heat storage material comprising the sodium acetate trihydrate and the liquid additive can be configured to have a melting point of about 60 ° C. Thereby, more suitable cooling can be given to the cooling of the power cable.

  Further, ethylene glycol can be used as the liquid additive. Ethylene glycol is a stable liquid that does not cause chemical reaction with sodium acetate trihydrate, has better thermal conductivity than sodium acetate trihydrate, and compared to sodium acetate trihydrate. Although it is inferior, it also has a heat storage property. Furthermore, it has a good compatibility with water and can smoothly exchange water with sodium acetate trihydrate and give softness or fluidity even during solidification.

  The sodium acetate trihydrate and the ethylene glycol are mixed at a weight ratio of about 10: 2 to 10: 5. Thereby, the softness | flexibility thru | or fluidity | liquidity which can be arrange | positioned in a pipe line can be given by enclosing in a flexible pack member.

  The pack member has a two-layer structure of a vinyl chloride material and a polyethylene material. Thereby, the water and ethylene glycol at the time of melting of sodium acetate trihydrate can be sealed without permeation, and the heat storage material can be solidified and melted stably.

And a jig having at least two holding members slidable across the power cable, wherein one end portion of the pack member enclosing the heat storage material is held by one holding member, and the other end The jig in which the one and the other holding members are connected to each other so that the portion is held by the other holding member and the tension is not applied to the pack member even when the holding member is pulled. it can be used, configured to arranged the pack member in the duct by pulling the jig the packed member is fixed to the conduit. Thereby, it can arrange | position in a pipe line, without applying excessive force to the pack member with which the thermal storage material was enclosed, can improve the ease of arrangement | positioning, and tension is added. It is possible to prevent the pack member from being damaged.

  According to the heat storage material of the present invention, it is possible to provide a heat storage material having softness or fluidity even at the time of solidification. For example, it can be easily used as a cooling means for power cables laid in pipes, troughs, or caves. Can be applied. Moreover, since it has favorable heat conductivity, to-be-cooled objects, such as a power cable, can be cooled effectively by the heat conductivity and / or latent heat.

  According to the method for cooling a power cable of the present invention, it can be applied to a pipeline without exchanging the power cable itself or sealing the end face of the pipeline, so that the existing pipeline in which the power cable has already been laid is provided. It can be easily applied to.

  Moreover, the heat storage material which has about 60 degreeC melting | fusing point can be comprised, and it becomes possible to perform cooling of an electric power cable more effectively.

  In addition, ethylene glycol can be used as a liquid additive to be mixed with sodium acetate trihydrate, and the thermal conductivity of the heat storage material is improved compared to sodium acetate trihydrate itself. The heat radiation to the outside can be further improved.

  Further, by mixing sodium acetate trihydrate and ethylene glycol in a weight ratio of about 10: 2 to 10: 5, a pack that can be given softness or fluidity even at the time of solidification and in which a heat storage material is enclosed The degree of freedom of the shape is given to the member, and the ease of arrangement work in the pipe line can be achieved.

  In addition, the pack member in which the heat storage material is sealed has a two-layer structure of vinyl chloride and polyethylene, so that the heat storage material can be solidified and melted stably without causing leakage of moisture or ethylene glycol. be able to.

  Further, since the pack member encapsulating the heat storage material is arranged by being pulled into the pipe line through a jig so as not to apply tension, the ease of arrangement in the pipe line is improved. In addition, it is possible to prevent the pack member from being damaged due to the applied tension.

  As the best mode for carrying out the invention, examples of the present invention will be described below.

  FIG. 1 is a schematic view for explaining an example of a method for cooling a power cable according to the present invention, and shows a pipe line 2 provided in the underground 1.

  The pipe line 2 is formed of, for example, a hard vinyl chloride pipe (EIP) or the like, and is provided between the manholes 3A and 3B. In the pipe line 2, a power cable 4 such as a triplex type CV cable is laid. ing. The power cable 4 is connected to the other power cables 6A and 6B via the connection portions 5A and 5B in the manholes 3A and 3B, and constitutes an underground transmission line. In this example, reference symbol P indicates a heat spot location where the temperature rises locally, such as a subway intersection, and the heat storage material 7 according to the present invention is enclosed in a flexible pack member 8 in this heat spot location P. Are disposed in the gap between the pipe line 2 and the power cable 4.

  The heat storage material 7 is mainly composed of sodium acetate trihydrate, and compared with sodium acetate trihydrate in order to prevent the sodium acetate trihydrate from hardening even at a temperature below its melting point (58 ° C.). Liquid additives with good thermal conductivity are mixed. Thereby, the heat storage material 7 is configured to have softness or fluidity even at the time of solidification and to have better thermal conductivity as compared with sodium acetate trihydrate alone. The liquid additive mixed with sodium acetate trihydrate is a stable liquid that does not cause chemical reaction with sodium acetate trihydrate, has better thermal conductivity than sodium acetate trihydrate, Although it is inferior to sodium acetate trihydrate, it also has heat storage properties. Furthermore, it is compatible with water and can exchange water with sodium acetate trihydrate smoothly, and can give softness or fluidity to solidified sodium acetate trihydrate.

  As an example of a liquid additive having such properties, ethylene glycol can be used. Ethylene glycol is a liquid, and the present inventor has a softness that allows insertion into the conduit 2 when sodium acetate trihydrate and ethylene glycol are mixed at a weight ratio of about 10: 2 to 10: 5. It was experimentally found that the heat storage material 7 can be given fluidity. Since ethylene glycol is inferior in heat storage performance compared with sodium acetate trihydrate, increasing the weight ratio of ethylene glycol causes a decrease in the heat storage performance of the heat storage material 7. Moreover, when there is little weight ratio of ethylene glycol, the softness | flexibility thru | or fluidity | liquidity of the thermal storage material 7 will fall. Based on this point of view, the present inventor has found that the mixing ratio of sodium acetate trihydrate and ethylene glycol is preferably about 10: 3 by weight. Thereby, as described below, the heat storage material 7 having a melting point of about 60 ° C. suitable for cooling the power cable can be obtained.

A comparison result between the heat storage material 7 in which sodium acetate trihydrate and ethylene glycol are mixed at 10: 3 and sodium acetate trihydrate alone is shown below.
Melting point of heat storage material 7: 59.5 ° C. (sodium acetate trihydrate simple substance: 58 ° C.)
-Latent latent heat of heat storage material 7: 180.8 J / cm ³ (sodium acetate trihydrate simple substance: 178 J / cm ³ )
Such a heat storage material 7 has softness or fluidity at the time of solidification, that is, 59.5 ° C. or less, and also has a higher thermal conductivity than sodium acetate trihydrate alone even at the time of solidification. Confirmed by the inventor.

  FIG. 2 is a plan view showing an example of the pack member 8 in which the heat storage material 7 is enclosed, and FIG. 3 is a cross-sectional view taken along the line AA of FIG.

  The pack member 8 is a flexible bag member made of, for example, plastic having a high degree of freedom in shape, and may leak moisture generated when sodium acetate trihydrate melts and ethylene glycol, which is a liquid additive, to the outside. In addition, for example, in the case of a CV cable, since the allowable temperature for a short time is 105 ° C., it is configured to have a heat resistance of 120 ° C. or higher, which is a temperature higher than that. Furthermore, it is desirable to have sufficient strength so as not to be broken when inserted into the pipe line 2 and to be in contact with the power cable 4 so as not to cause an electrical trouble. .

  In this example, the pack member 8 has a two-layer structure of a layer 8a made of a vinyl chloride material and a layer 8b made of a polyethylene material, and transmits water and ethylene glycol when sodium acetate trihydrate is melted. The heat storage material 7 can be enclosed without causing the heat storage material 7 to have sufficient heat resistance, strength, and flexibility. Vinyl chloride material does not permeate ethylene glycol but permeates moisture, and polyethylene material does not permeate moisture but permeates ethylene glycol, but has a two-layer structure that allows both to permeate. The heat storage material 7 can be solidified and melted stably.

  The width W of the pack member 8 is appropriately selected based on the inner diameter of the pipe line 2 and the like, and the length L is appropriately selected based on the workability in the manholes 3A and 3B. For example, the width W is 150 mm, The length L is selected to be 1200 mm. Both end portions 10 of the pack member 8 are sealed, for example, by heat welding or the like, so that the heat storage material 7 does not leak to the outside. The both end portions 10 are respectively provided with eyelets 11 for fixing to a jig described later. Such a pack member 8 is disposed in the pipe 2 by using a jig described in FIGS. 4, 5, and 6.

  4 is a perspective view showing an example of a jig, FIG. 5 is a perspective view showing a holding member in FIG. 4, and FIG. 6 is a development view of the jig in FIG. In this example, the jig 15 has three holding members 16A, 16B, and 16C, and as shown in FIG. 6, six pack members 8 in which the heat storage material 7 is sealed are fixedly held by the holding members 16A to 16C. It has come to be.

  Since the holding members 16A to 16C are in contact with the power cable 4, it is preferable that the holding members 16A to 16C are made of an insulator so as not to cause an electrical trouble. In this example, the holding members 16A to 16C are made of vinyl chloride. The holding members 16 </ b> A to 16 </ b> C are substantially C-shaped in this example, and are configured to be slidable across the power cable 4. In the holding members 16A to 16C, a plurality of connection holes 17 and a plurality of holding holes 18 are formed in this example. The connecting hole 17 is for connecting the holding members 16A and 16B and the holding members 16B and 16C to each other, and for connecting the holding members 16A and 16C to the pull-in rope 19, and the holding hole 18 is This is for fixing and holding the six pack members 8.

  The holding members 16A and 16B and the holding members 16B and 16C are configured to pull the holding members 16A and 16C in opposite directions under a state in which the pack member 8 in which the heat storage material 7 is sealed is fixedly held by the holding members 16A to 16C. However, the pack members 8 are connected by the connecting ropes 20 via the connection holes 17 so that the tension is not applied to the pack members 8 and the pack members 8 are not loosened excessively. As an example, the fixing of one pack member 8 to the holding members 16A and 16B will be described. One end portion of the pack member 8 is connected to the holding member 16A via the eyelet 11 provided on one of the both end portions 10 of the pack member 8. The other end portion of the pack member 8 is similarly fixed to the corresponding holding hole 18 of the holding member 16B via the eyelet 11 fixed to the holding hole 18 with a string or a rope and provided on the other of the both end portions 10 of the pack member 8. Or it is fixed with a rope. Similarly, the other pack members 8 are fixedly held by the holding members 16A and 16B and the holding members 16B and 16C. In this example, each pack member 8 is fixedly held on the upper side of the holding members 16A to 16C. However, the present invention is not limited to this, and the pack member 8 is fixedly held on the lower side of the holding members 16A to 16C. It may be. A holding rope 16 is connected to the holding members 16A and 16C of such a jig 15, and the jig 15 in which the pack member 8 is fixedly held by pulling the drawing rope 19 passed through the pipe line 2. Will be pulled into the pipe 2.

  FIG. 7 is a view for explaining a method of arranging the pack member in which the heat storage material is sealed in the pipe line, and FIG. 8 is a view showing a BB cross section of FIG.

  Each pack member 8 in which the heat storage material 7 is sealed is fixedly held by the holding members 16A to 16C of the jig 15 as described above, and the jig 15 is moved to the arrow with the pull-in rope 19 passed through the pipe line 2, for example. By being pulled in the direction indicated by a (the right direction in FIG. 7), it is inserted into the pipe line 2. The pull-in rope 19 is connected to a messenger wire (not shown) made of, for example, a plastic having features such as a streak. , Is passed through the conduit 2. Before pulling the jig 15 on which the pack member 8 is fixed and held into the pipe line 2, for example, a cloth member soaked with a lubricant is passed through the pipe line 2 to pass through the inner surface of the pipe line 2 and the power cable 4. A lubricant is applied to the outer surface of the material, and a lubricant is also applied to the pack member 8 and the jig 15 so that the jig 15 can be easily pulled into the pipe 2.

  The jig 15 slides so as to straddle the power cable 4 as shown in FIG. 8 when the pull-in rope 19 is pulled, and is pulled into the desired heat spot location P, and the pack in which the heat storage material 7 is enclosed. The member 8 is disposed at the heat spot location P. If the pack member 8 falls into the side portion N where the power cable 4 and the inner surface of the pipe line 2 are narrowed during the retraction of the jig 15, the retraction of the jig 15 may be hindered. So as not to fall into such a side portion N, the pulling rope 19 connected to the holding member 16A is pulled in the direction indicated by the arrow b opposite to the direction a (the left direction in FIG. 7), and is always backed. It is pulled into the pipe line 2 while applying tension. Even after the pack member 8 encapsulating the heat storage material 7 is disposed at the heat spot P, the jig 15 is left together with the pack member 8. Therefore, for example, if the pack member 8 needs to be replaced for some reason, the pack member 8 can be extracted from the pipe line 2 via the pull-in rope 19. Since the jig 15 is placed in contact with the power cable 4 as described above, it is desirable that the jig 15 be made of an insulator.

  In general, the transmission line load changes between daytime and nighttime. At nighttime, the transmission line load decreases and the ambient temperature also decreases, so the amount of heat generated by the power cable 4 decreases, and conversely the transmission line load increases during the daytime. As the ambient temperature rises, the calorific value increases. In this case, when the pack member 8 in which the heat storage material 7 is enclosed is disposed as described above, the cold air at night is stored and the power cable 4 is cooled when the amount of heat generated during the day is large, A reduction in power transmission capacity due to heat generation can be prevented. As described above, since the heat storage material 7 has a low melting point of about 60 ° C., the power cable 4 can be effectively cooled. In addition, since it has softness or fluidity even at temperatures below this melting point and has good thermal conductivity, it has high thermal conductivity compared to air or the like even below the melting point of the heat storage material 7. The heat from the power cable 4 is effectively radiated to the outside.

The present inventor uses a pipe with an inner diameter of 150 mmΦ in which a 250 mm ² 33 KV triplex CV cable is installed as a power cable as a test pipe, and arranges the heat storage material according to the present invention in the pipe. The conductor temperature of the power cable was measured when it was not installed. As the heat storage material, a mixture of sodium acetate trihydrate and ethylene glycol at a weight ratio of 10: 3 is used, and the heat storage material is sealed in a pack member having a width of 150 mm and a length of 1200 mm. Twenty-one pack members (weight: about 52.5 kg) were disposed in the pipe line. As described below, the test condition is a heat cycle in which power is supplied so that the conductor temperature of the power cable is 90 ° C. (maximum temperature for normal use) and 105 ° C. (short-term allowable temperature) in the absence of a heat storage material. I went there.

  FIG. 9 is a diagram showing a heat cycle for giving 90 ° C. and 105 ° C. as the conductor temperature of the power cable in the absence of the heat storage material. As shown in FIG. 9, when there is no heat storage material, the holding current (560 A) is energized for 9 hours so that the conductor temperature of the power cable is 90 ° C., and then the energization is turned off for 15 hours. When there was no material, a holding current (620 A) was applied for 9 hours so that the conductor temperature was 105 ° C. As a result, the measurement results shown in FIGS. 10 and 11 were obtained with and without the heat storage material when the conductor temperature of the power cable was 90 ° C. and 105 ° C., respectively.

  FIG. 10 shows the measurement results of the conductor temperature of the power cable corresponding to the presence or absence of the heat storage material during energization giving 90 ° C. as the conductor temperature of the power cable. In FIG. 10, the measurement result A shows the conductor temperature of the power cable when there is no heat storage material, the measurement result B shows the conductor temperature when there is a heat storage material, and the measurement result C shows the surface temperature of the heat storage material. ing. As is clear from FIG. 10, the conductor temperature B of the power cable in the presence of the heat storage material was confirmed to be about 14 to 20 ° C. lower than the conductor temperature A in the absence of the heat storage material. Although the surface temperature of the heat storage material at this time is about 45 ° C., it can be seen that a large cooling effect is obtained by the good thermal conductivity of the heat storage material.

  FIG. 11 shows the measurement results of the conductor temperature of the power cable corresponding to the presence or absence of the heat storage material during energization giving 105 ° C. as the conductor temperature of the power cable. In FIG. 11, the measurement result D shows the conductor temperature of the power cable when there is no heat storage material, the measurement result E shows the conductor temperature when there is a heat storage material, and the measurement result F shows the surface temperature of the heat storage material. ing. As is clear from FIG. 11, the conductor temperature E when the heat storage material is present is confirmed to be about 15 to 20 ° C. lower than the conductor temperature D when there is no heat storage material. The conductor temperature E of the power cable when there is a heat storage material is slightly lower than the conductor temperature A shown in FIG. 10 when there is no heat storage material, and the transmission capacity is increased by arranging the heat storage material. You can see that That is, since the holding current in the case of the measurement result A in FIG. 10 is 560 A and the holding current in the case of the measurement result E in FIG. 11 is 620 A, the conductor temperature of the power cable is the same or less by using the heat storage material. Under the following conditions, a current of 620A / 560A = 1.1 times can be passed. The surface temperature F of the heat storage material is about 53 ° C. at the maximum, and the heat storage material shifts in the solidification direction when the current is turned off, so that it is understood that the cooling effect is obtained by both good thermal conductivity and latent heat. .

  Needless to say, the present invention can be applied not only to a pipeline in which a power cable has already been installed, but also to a newly established pipeline. Further, the triplex type CV cable has been described as an example, but the present invention is not limited to this, and it is needless to say that the present invention can be effectively applied to a single-core power cable or the like.

  The heat storage material according to the present invention can be used not only for cooling power cables but also for other objects to be cooled, and not only for cooling power cables in pipes but also for laying in troughs and caverns where temperature differences occur. It can also be used for power cables that have been used.

FIG. 1 is a schematic view for explaining an example of a method for cooling a power cable according to the present invention. FIG. 2 is a plan view showing an example of a pack member in which a heat storage material is enclosed. 3 is a cross-sectional view taken along the line AA in FIG. FIG. 4 is a perspective view showing an example of a jig. FIG. 5 is a perspective view showing the holding member in FIG. FIG. 6 is a development view of the jig shown in FIG. FIG. 7 is a view for explaining a method of arranging the pack member in which the heat storage material is enclosed in the pipe line. FIG. 8 is a view showing a BB cross section of FIG. FIG. 9 is a diagram showing a heat cycle for giving 90 ° C. and 105 ° C. as the conductor temperature of the power cable in the absence of the heat storage material. FIG. 10 is a diagram showing the measurement results of the conductor temperature of the power cable corresponding to the presence or absence of a heat storage material during energization giving 90 ° C. as the conductor temperature of the power cable. FIG. 11 is a diagram showing the measurement results of the conductor temperature of the power cable corresponding to the presence or absence of the heat storage material during energization giving 105 ° C. as the conductor temperature of the power cable.

Explanation of symbols

2 Pipe line 4 Power cable 7 Heat storage material 8 Pack member 15 Jigs 16A, 16B, 16C Holding member 19 Pull-in rope 20 Connecting rope

Claims (9)

And sodium acetate trihydrate as a main component, the sodium acetate trihydrate is a liquid additive of ethylene glycol is also mixed with the sodium acetate trihydrate to not cured in a temperature below the melting point By having a component effective for heat storage mixed in a weight ratio of 10: 2 to 10: 5, it has softness or fluidity even during solidification and higher thermal conductivity than the sodium acetate trihydrate . thermal storage material configured so as to have the flexibility in contact with the slidable across the heat spot of the power cable in a two-layer structure is composed of a power cable laying the pipe of the vinyl chloride-based materials and polyethylene-based materials And a pair of eyelets provided with strings or ropes that are drawn into the heat spots at both ends of the pack member. Bull cooling pack member. The power cable cooling pack member according to claim 1, wherein the heat storage material comprising the sodium acetate trihydrate and the liquid additive comprising ethylene glycol has a melting point of 60 ° C. The power cable cooling pack member according to claim 1, wherein a plurality of the pack members are held.   4. The power cable cooling pack member according to claim 3, wherein a plurality of the pack members are held by a jig having a holding member slidable across the power cable. In the method for cooling an electric power cable installed in a pipeline, a heat storage material is enclosed in a flexible pack member having a two-layer structure of a vinyl chloride material and a polyethylene material, and the heat storage material is enclosed. At least one of the pack members is slidably disposed across the heat spot of the power cable in the conduit,
The heat storage material disposed in said conduit comprises a sodium acetate trihydrate as a main component, the sodium acetate trihydrate is the sodium acetate trihydrate to prevent curing in the temperature below the melting point The liquid additive composed of ethylene glycol mixed with the product has a component effective for heat storage mixed at a weight ratio of 10: 2 to 10: 5, so that it has softness or fluidity even during solidification. With a higher thermal conductivity than sodium acetate trihydrate ,
With a string or rope having via eyelets provided at both ends of the pack member, it is pulled into the heat spot and fixed,
The method of cooling a power cable, wherein the power cable is cooled by thermal conductivity and / or latent heat of the heat storage material. 6. The method for cooling a power cable according to claim 5, wherein the heat storage material comprising the sodium acetate trihydrate and the liquid additive comprising ethylene glycol has a melting point of 60 ° C. A jig having at least two holding members slidable across the power cable, wherein one end portion of the pack member enclosing the heat storage material is held by one holding member, and the other end portion is The one and the other holding members are configured to be held by the other holding member, and so that the tension is not applied to the pack member even if the holding member is pulled to the heat spot by the string or rope and pulled. Using the jigs connected to each other,
The power cable according to claim 5 or 6 , wherein the pack member is disposed in the pipe line by drawing the jig to which the pack member is fixed into the pipe line. Cooling method.   At one end and the other end of the jig, retracting means extending in directions opposite to each other are provided by the string or rope, respectively, and at the same time, the other retracting means is pulled by the pulling of the one retracting means. The power cable cooling method according to claim 7, wherein the jig is pulled together with the pack member into the pipe line while being pulled in a direction opposite to the direction. The method for cooling a power cable according to claim 7, wherein a plurality of the pack members are held.

Images