JPS5911162B2 - Low temperature resistant electric cable line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel low temperature resistant electric cable line.

5- In general, power and instrumentation cables that are wired inside and outside of tanks used for storing or transporting liquefied gas must be resistant to low temperatures.

In particular, pump power cables used while immersed in liquefied gas are required to have low-temperature resistance. 10 Conventionally, MI cables and tetrafluoroethylene cables have been used as cables that can withstand this type of extremely low temperature.

However, in MI cables, the cable sheath is made of copper coating, so although it has excellent impact resistance, it has poor flexibility15. Extreme care must be taken when carrying out lifting operations. In addition, the sheath layer of the tetrafluoroethylene cable is made of a tetrafluoroethylene coating, so although it has better flexibility than the copper material 20 mentioned above, it is difficult to bend at low temperatures. When applying this method, it was difficult to obtain a sufficient bending radius. Therefore, when laying such low-temperature cables or pulling them up, it was not possible to perform drum winding, etc.25, and the work had to be carried out by hand with extreme caution. There was a demand for the development of a flexible cable with excellent low-temperature flexibility and impact resistance.

The present invention was developed as a result of intensive research in response to such requests.
We have discovered a low-temperature resistant cable that has excellent flexibility and impact resistance at low temperatures.Inorganic and organic Alternatively, a cable consisting of a buffer layer made of braided natural fibers and a sheath layer made of twisted metal tape on the outside 35 of the braided metal wire is placed in an atmosphere of low-temperature liquefied gas to run an electric cable line. It is characterized by comprising the following.

An example of the present invention will be explained in detail based on the drawings.

As shown in FIG. 1, an insulating layer 3 is formed by winding a large number of layers of plastic tape with excellent low temperature properties, such as polyester resin tape or tetrafluoroethylene tape, on the conductor 2.
A buffer layer 4 made of braided inorganic fibers such as glass fibers or natural fibers such as cotton yarn is provided on the outside, and copper wires,
The cable 1 is obtained by winding brass wire or the like into a copper tape, providing a sheath layer 5, and filling the insulating layer with low temperature liquefied gas. In the present invention, the low-temperature-resistant plastic used to form the insulating layer is preferably a polyester resin that has excellent low-temperature flexibility.
Formed by winding 0 layers.

By constructing an insulating layer using such plastic tape, the low temperature flexibility and impact properties can be significantly improved, and the cable 1 can be inserted into the tank 7 through the barrel 6 as shown in FIG. cable 1 in case
The cable size and capacity can be easily accommodated as the capacity of the gas suction pump 8 increases, which is attached to the tip of the cable.

Furthermore, in addition to the insulation performance of the polyester resin itself, the liquefied gas immersed in the insulation layer can significantly improve the insulation properties of the cable. In addition, the reason for providing a buffer layer is that if a shock is received while laying or pulling up a cable as mentioned above, the shock layer will cushion the impact and prevent damage to the internal insulation layer. This is to ensure that.

Therefore, the buffer layer has excellent flexibility and impact resistance at low temperatures.
In addition, in order not to impair flexibility, the desired performance is achieved by braiding inorganic fibers such as glass fibers or natural fibers such as cotton yarn to form a network. The reason why the above effects can be obtained by forming a buffer layer by braiding and reticulating fibers is that natural and inorganic materials generally tend to become harder at extremely low temperatures compared to room temperature. By making this hardening tendency into a fibrous form and further making it into a braided shape, the hardening of individual fibers is alleviated by the shearability of the braided network, thereby improving performance such as impact resistance and flexibility. I am trying to make the most of it.

Further, the sheath layer is provided to prevent damage to the sheath layer when the cable receives an impact. Therefore, it must have excellent impact resistance and flexibility at low temperatures, and is formed by braiding metal wire, especially brass wire, or by wrapping metal tape. When the sheath layer is provided by braiding metal wires, the outer diameter of the wires is preferably about 0.32 mm and the thickness is about 0.8 mm, and the mesh of the braid is preferably from 5 to 10 q6.

Next, examples of the present invention will be described.

Eight pieces of polyester tape with a thickness of 0.05 mm are wrapped around a brass wire with an outer diameter of 6.8 mm using % wrap, and the outer diameter of the tape is 0.12 F! 1 glass fiber braid (thickness 0.2
1mm) to form a buffer layer, and further outside the buffer layer with an outer diameter of 0.
．． 32m7! A sheath layer was provided by braiding brass wire (thickness: 0.8 mm), and the insulating layer was filled with liquid nitrogen gas to obtain a low temperature resistant electric cable line of the present invention.

The results of measuring the electrical characteristics of the cable of the present invention at -192°C are shown in Table 1.

For comparison with the cable of the present invention, the electrical characteristics of a conventional MI cable (conductor diameter: 6.8 mm) IfC were also measured in the same manner as above, and the results are also listed in Table 1.

In addition to the cable of the present invention, as a comparative example, Teflon tape was wound in multiple layers to a thickness of approximately 0.9 mm on a 60㎜ annealed copper stranded conductor, and a glass thread braided layer was formed thereon to a thickness of 0.2 mm. As a result of measuring the insulation resistance, breakdown voltage, impact resistance and flexibility at -192℃ of a low-temperature electric cable with a Teflon sheath layer formed thereon, the insulation resistance was 4.7 x 103MΩ・b, and the breakdown voltage is 32KV,
The impact resistance and flexibility were as shown in Table 2.

The impact resistance was measured using 10 kg MVC.

As is clear from the above table, the low-temperature resistant electric cable line of the present invention has excellent impact resistance and flexibility, so it is possible to greatly reduce the work time and number of manpower when installing the cable. It has remarkable effects such as being able to easily carry out the work of drum removal and gripping in a narrow work area when pulling up.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a low-temperature-resistant electric cable according to the present invention, and FIG. 2 is a schematic explanatory diagram showing how the low-temperature-resistant electric cable line of the present invention is used. 1... Cable, 2... Conductor, 3... Insulating layer, 4
... Buffer layer, 5... Sheath layer, 6... Barrel, 7
...Nunc, 8...Pump.

Claims (1)

[Claims] 1. A buffer layer made of braided inorganic fibers or natural fibers is provided on the outside of the insulating layer formed by winding a low-temperature-resistant plastic tape on the conductor, and a braided metal wire or wrapped metal tape is further provided on the outside of the insulation layer. A low-temperature-resistant electric cable line, characterized in that the electric cable line is constructed by placing a cable provided with a sheath layer made of windings in a low-temperature liquefied gas atmosphere.