JPS6346983Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to power cables.

As is well known, the power transmission capacity of a power cable is greatly influenced by its insulation properties, and when the transmission power is increased, there is a risk that the insulation properties will deteriorate due to heat generation in the cable and that the cable itself will be damaged. In order to increase the power transmission capacity of a cable, it is necessary to improve its insulation properties and heat resistance, or to cool the cable itself. Conventionally, pipe-shaped cables and gas-insulated cables have been known as power cables with structures that can be actively cooled.
In order to perform active cooling, it is necessary to circulate oil as a pressure medium, so a pumping plant consisting of a pump, oil tank, etc. must be installed, making the equipment complicated and expensive, and running costs increase. There are other problems. The latter type of gas-insulated cable suppresses the temperature rise due to conductor loss through heat conduction and convection of SF ₆ gas, which makes up most of the insulator, but it is not always possible to obtain a sufficient cooling effect. Moreover, in both the former pipe type cable and the latter gas insulated cable, heat is transferred as sensible heat from the oil or gas insulator, so the cooling effect is low and the insulation properties deteriorate due to heat generation. It has been difficult to increase power transmission capacity from the perspective of preventing power decline.

The purpose of this invention is to provide a power cable that can effectively solve the above problems.The conductor has a sealed hollow structure, and when heat is applied to the inside, it evaporates and radiates heat. A working fluid that condenses and transports heat as latent heat is sealed in the conductor, and a wick is provided inside the conductor to allow the liquid-phase working fluid to flow back through capillary action, and is tightly attached to the outer periphery of the end of the conductor. The present invention is characterized in that a heat dissipation section is provided, and an end of the conductor is provided so as to protrude a predetermined length from an end of the heat dissipation section.

An embodiment of this invention will be described below with reference to the drawings. FIG. 1 is a partial longitudinal cross-sectional view showing an embodiment of this invention, and FIG. 2 is a cross-sectional view taken along the line -. A conductor made of metal such as copper or aluminum, which is formed in a hollow shape with both ends sealed, and which has a capillary action such as a thin groove or metal mesh running along the axial direction on the inner peripheral surface of the conductor 1. Further, a condensable working fluid is sealed inside the conductor 1 after a non-condensable gas that does not condense at room temperature, such as air, is vacuum-suctioned and exhausted. As described below, the working fluid evaporates and flows, then radiates heat and condenses, thereby transporting heat as latent heat, and evaporates at room temperature or a slightly higher temperature of 40 to 60 degrees Celsius. is preferable, and for example, methanol or water can be used if the inside of the conductor 1 is under reduced pressure.

Then, an insulating layer 3 made of insulating paper or rubber is formed on the outer peripheral surface of the conductor 1 except for the end (the left end in FIG. 1), and a protective layer 4 made of chloroprene or the like is formed on the outer peripheral surface. It is formed. Further, a heat dissipating portion 5 is provided at the end of the conductor 1 so as to be in close contact with the outer circumferential surface of the end and to protrude by a predetermined length. The heat dissipation section 5 is provided with a large number of fins 5a along the radial direction of the cable, and is configured to transfer heat generated during power transmission to the outside air. The fins 5a are preferably made of metal in order to improve thermal conductivity, but if there is a risk of arcing, an arc ring may be provided, for example.

However, when power is transmitted through the power cable having the above configuration and heat is generated due to conductor loss, the working fluid sealed inside the conductor 1 receives heat and evaporates, and the vapor is released into the low pressure areas within the conductor 1, i.e. Heat radiation part 5
Flows to the place where the water is placed. Since the heat inside the cable is released from the heat radiating section 5 to the atmosphere or to the coolant, the gas phase working fluid that reaches the location where the heat radiating section 5 is provided transfers heat to the wick 2 at that location and condenses. That is, the working fluid transports heat generated by conductor loss as latent heat of the working fluid to the location where the heat radiating section 5 is provided. At the location where the working fluid evaporates, capillary pressure is generated due to the evaporation of the liquid-phase working fluid, and as a result, the working fluid condensed and liquefied at the location where the heat dissipation section 5 is provided flows back inside the wick 2 due to the capillary pressure. Then, the refluxed liquid-phase working fluid receives heat again and evaporates, repeating the above-mentioned operation, and the working fluid repeats evaporation and condensation as described above and circulates, thereby being used for power transmission. The accompanying heat is continuously released to the atmosphere, cooling fluid, etc., and as a result, the rise in temperature of the cable is suppressed.

Note that heat transfer is performed repeatedly as the condensed and liquefied working fluid circulates inside the wick 2, so if the heat dissipation section 5 is set at a higher position than the other parts, the condensed and liquefied working fluid will be removed. Since the fluid is refluxed by capillary pressure and gravity to the point where evaporation is occurring, the reflux distance, in other words the distance over which heat transport can take place, can be made longer. In addition, when the inside of the conductor 1 is a single sealed chamber, the length of the sealed chamber is limited to a certain length because the distance over which the liquid phase working fluid can circulate is restricted due to the flow resistance of the conductor 2. Therefore, the length of the conductor 1, that is, the length of the cable, is limited, and there are cases where it is not possible to make the cable the desired length. If the wick is installed in each sealed chamber, a working fluid is sealed in each sealed chamber, and each sealed chamber is set to a length that allows the liquid-phase working fluid to flow back, the working fluid will flow in each sealed chamber. Heat transport is carried out by the circulating flow through repeated evaporation and condensation, and heat conduction occurs between each sealed chamber through the partition walls, so heat transport can be carried out over the entire length. Therefore, the length of the conductor 1, that is, the cable, can be set to be long without being particularly restricted by the return distance of the liquid phase working fluid.

Furthermore, when connecting cables, insulating layer 3
By abutting the ends of the conductors 1 on which the protective layer 4 is not formed and connecting them in the axial direction, it is possible to connect electrically and at the same time to enable heat transfer. Since the heat dissipation portions 5 are provided at the connected ends, the connection can be easily made without deteriorating the heat dissipation performance. Furthermore, since it is easy to attach the heat dissipating section 5 and connect the cable, it is suitable for a prefabricated cable construction method.

In the above embodiment, an example of a single-core cable was explained, but this invention is not limited to a single-core cable, but can also be applied to a three-core cable, in which case a three-core cable provided with an insulating layer 3 The book conductors 1 may be bound together with a protective layer with a jute or the like interposed therebetween. Further, in this invention, a container containing cooling oil may be attached to the outer periphery of the terminal end of the conductor 1 as the heat radiating portion 5, and the cooling oil may be circulated between an appropriate cooling device and the like.

As is clear from the above explanation, according to the power cable of this invention, the heat generated during power transmission can be transported to the heat dissipation part as latent heat of the working fluid sealed inside the conductor and released to the outside of the cable. This allows you to suppress the temperature rise of the cable.
Therefore, even if the transmitted power is increased, the temperature will not rise and the insulation properties will not deteriorate accordingly, so the power transmission capacity can be increased more than ever before. Furthermore, no particular power is required to dissipate the heat, or in the case of forced cooling, only a portion of the cable needs to be cooled, so the device is extremely simple and running costs can be kept low. Furthermore, the cable connection has the advantage that electrical connection and connection for heat transfer can be simultaneously and easily achieved.

[Brief explanation of the drawing]

FIG. 1 is a partial longitudinal cross-sectional view showing an embodiment of this invention, and FIG. 2 is a cross-sectional view taken along the - line in FIG. 1. 1... Conductor, 2... Width, 3... Insulating layer,
4...protective layer, 5...heat dissipation section.

Claims (1)

[Scope of utility model registration request] An insulating layer and a protective layer are sequentially formed on the outer periphery of a sealed hollow conductor, which has a capillary action capillary on its inner peripheral surface and a condensable working fluid sealed inside, except for the ends of the sealed hollow conductor. Further, a heat dissipating section is provided at the end portion on which the insulating layer and the protective layer are not formed so that the heat dissipating section is in close contact with the outer periphery of the heat dissipating section and protruding from the end portion of the heat dissipating section by a predetermined length. A power cable characterized by: