JPS6029313Y2 - Expansion joint device for cryogenic cables - Google Patents

Description

[Detailed explanation of the invention] This invention is a superconducting cryogenic resistive cable that reliably absorbs the expansion and contraction of the cable due to temperature changes without causing changes in the electrical characteristics, and ensures the connection between the cable conductors. This invention relates to a telescopic joint device for cryogenic cables such as cables.

The increasing demand for electricity and the difficulty of securing underground power transmission routes in urban areas require cables that can transport large amounts of power. One way to do this is to cool the cable conductors with a cooling medium such as liquid nitrogen. Research is being widely conducted on so-called cryogenic resistance cables, which aim to improve power transmission capacity by effectively capturing heat generated by conductor loss, dielectric loss, pipe loss, etc.

According to this method, the transport power can be increased by about five times compared to conventional OF cables, etc., but one of the problems in implementing it is that the cable conductor shrinks during cooling. There are difficulties in connecting cables to each other.

In other words, the amount of contraction of the cable conductor during cooling is at most 0.3
%, that is, the cable length reaches about 0.3m in 100m1, and the cable connection part reaches 0.6yrL.
It acts as a contraction of.

Therefore, it is essential to provide a joint that expands and contracts in response to contraction, and various studies have been carried out in the past.A representative example of this is the cross-sectional view shown in Figures 1a and 1b. Proposed.

This telescopic joint is connected to the hollow refrigerant passage a/b of the cable conductors a and b.

A hollow connecting pipe C for forming a refrigerant passage whose both ends are slidably inserted into b', a spacer d1 provided in the middle thereof, an electrostatic shielding cylinder e1, and cable conductors a and b; It consists of expansion and contraction absorbing conductors Lg connected to create current paths between the spacers 6, and operates as follows to connect the cables without damaging the electrical connection between the cables. It absorbs shrinkage.

That is, at room temperature, conductor L is connected to cable conductors a and b.
The structure is such that the conductor L g is bent as shown in Figure 1 a, and after cooling, the conductor L g is stretched as shown in Figure 1 due to contraction of the cable conductor, so that the cable conductor L g is bent as shown in Figure 1 a. This makes it possible to maintain a good connection state.

However, in a device using such a conductor for absorbing expansion and contraction, when bending force is repeatedly applied due to temperature cycles between room temperature and low temperature that occur when power transmission is stopped for maintenance inspections, etc., the conductor Lg for contraction and contraction will break. Otherwise, the electrical connection may be disrupted.

In addition, if the cross-sectional area of the conductor Lg is made small in an attempt to prevent this, the current capacity will also be reduced, so even if an attempt is made to increase the power transmission capacity by cooling the cable, the shrinkage-absorbing conductor Lg
The degree of improvement in power transmission capacity will be low due to the heat generation of

In addition, the absorption length of the contraction of the cable conductor by such a bending type conductor Lg is about 172 times the length of the conductor for absorbing expansion and contraction, and it is difficult to increase the length in order to stabilize the bending operation of the conductor f9g. Therefore, a long absorption length cannot be obtained.

As a result, short cable intervals, for example 100 m, require expansion and contraction joints to be provided at each interval, which has the disadvantage of increasing equipment and maintenance costs.

The purpose of this project is to provide an expansion joint for cryogenic resistant cables that has a long absorption length for expansion and contraction of the cable and can operate electrically and mechanically stable. Explain details.

Figure 2 a and b are at room temperature (when the cable conductor is stretched),
FIG. 2 is a vertical cross-sectional view and a partial vertical cross-sectional view showing an embodiment of the present invention during cooling (when the cable conductor contracts).

In the figure, 1 and 2 are cable conductors, 1' and 2' are hollow refrigerant passages, 3 and 4 are insulators, and 3' and 4' are cable sheaths.

5 and 6 are crimping sleeves, which are formed so that both ends of the cable conductors 1 and 2 can be fitted and crimped.

Reference numeral 7 designates an internal cooling pipe, which includes first and second pipe portions 7a having different diameters;
7b, one end of 7b is inserted into one end of 7a with a small gap to form a sliding part 8, and the other end of each is fixed to the crimp sleeves 5, 6.

A refrigerant passage is formed between the refrigerant passages 1' and 2' of the cable conductors 1 and 2, and at the same time, the length can be changed by the sliding part 8 in response to expansion and contraction of the cable conductors 1 and 2.

Reference numeral 9 denotes a telescoping main current path body, which is made by twisting together flexible flexible wires, such as thin wires, and winds annealed copper strands of the same thickness as the cable conductors 1 and 2 around the internal cooling pipe 7. The ends thereof are fixed to the crimp sleeves 5, 6 to form the main current path when the crimp sleeves are crimped onto the cable conductors 1, 2.

Furthermore, when the annealed copper stranded wire is used at room temperature (when the cable conductor is stretched), for example, as shown in Fig. 2a, the inner diameter is larger than the outer diameter of the internal cooling pipe 7, there is no space between the wires, and the winding angle θ is θ〉45°
Wrap the required length and number of wires so that

When both ends of the annealed copper stranded wire are pulled outward to the left and right by the contraction of the cable conductors 1 and 2, the inner diameter changes from the initial value to the internal cooling pipe 7 while increasing the distance between the wires, as shown in Figure 2. The cable conductor 1 is elongated by reducing its outer diameter to
, 2 can be absorbed while maintaining a good connection state.

10 is a cylinder for conductor potential, and one end is inserted into the other end with a small gap to form a sliding part 11.
, second tube portions 10a, 10b, each having a tapered end portion concentrically fixed to the circumferential surface of the crimp sleeves 5, 6.

The diameter is selected in accordance with the outer diameter of the expandable main current path body 9 at room temperature.

12 is a cylinder for sheath potential and is formed from the following parts.

That is, one end has a cylindrical portion 13a' into which the cable sheath 3' can fit with little clearance, and a funnel-shaped first cylinder 13a and a second cylinder 13b that maintain airtightness with the sheath 3' by a gasket 13a''. A connection part 13b' that is airtightly connected via a refrigerant inlet 13b'' provided on the circumferential surface of the intermediate part, and a cable support cylinder 13 provided at the other end.
b The second cylinder 13b with a ``'' and the third cylinder 13c, that is, one end, slide on the inner peripheral surface of the second cylinder 13b, and as shown in FIG. 3, an airtight state is maintained by, for example, an O-ring 13C'. A funnel-shaped third portion having a cylindrical portion 13C″
It consists of a cylinder 13c1 and a reinforcing cylinder 13d, that is, a cable reinforcing cylinder 13d that is inserted so as to be able to slide inside the cable support cylinder 13b'' with little clearance and connected to the third cylinder 13c.

Its diameter is selected so as to provide a sufficient distance to insulate it from the conductor potential cylinder 10 using a coolant such as liquid nitrogen.

14 and 15 are insulating tape layers, 16 and 17 are windings for sheath potential, and 18 is an insulating refrigerant, such as liquid nitrogen. The telescopic joint device consisting of the above connects cables to each other in the following manner.

First, a crimp sleeve 5 to which the internal cooling pipe 7, the telescoping main current passage body 9, and the conductor potential cylinder 10 are fixedly connected, respectively;
6 is a cable conductor 1 with tapered insulators 3 and 4,
Fit it onto the end of 2 and crimp it.

Next, insulating tape layers 14 and 15 are formed by winding an insulating tape across the insulators 3 and 4 and the conductor potential cylinder 10 so as to have a taper on both sides so as to have the required insulation strength. Windings 16 and 17 for sheath potential are wound around the circumferential surface, leaving a taper on the cable side.

Next, the first cylinder 13a of the sheath cylinder 12 fitted onto one cable sheath 3' is covered with the insulating tape layer 1.
4 and fitted onto the other cable sheath 4' and connected to the cable reinforcing cylinder 13d, the second cylinder 13c is positioned on the insulating tape layer 15. 13b and connects to the first cylinder 13a to surround the connecting portion.

Finally, the refrigerant inlet 13b provided in the second cylinder 13b
'', insulating liquid nitrogen 17 is introduced into the space between the conductor potential cylinder 10 and the sheath potential cylinder 12 to complete the connection.

In this way, the coiled expandable main current path body 9 made of a flexible material such as stranded annealed copper wire is connected to the cable conductors 1°2 by crimp sleeves 5 and 6 to prevent the cable from shrinking. By absorbing the energy, it is possible to eliminate the risk of breakage due to repeated expansion and contraction, which is the case with conventional expansion and contraction absorbing conductors, resulting in a long lifespan and stable power transmission over a long period of time.

In addition, the cross-sectional area is not limited due to bendability, and the expandable main current path body 9 can have a cross-sectional area that provides the desired current capacity, so it is possible to realize a large-capacity cable system by cooling. It is possible.

In addition, the more the winding, that is, the length, of the telescopic main current path body 9, the greater the cable elongation when contracted, compared to conventional cables whose length is limited due to bendability. Absorption length can be increased.

Therefore, compared to the case where a conductor for expansion and contraction is used, the installation interval of expansion and contraction joint devices can be made longer.For example, it is possible to install the expansion joint device at intervals of 500m, which is five times the conventional method, so installation costs, maintenance costs, etc. can be reduced. It can be ordered.

In addition, in this case, the telescopic heavy current conductor 9 and the like can be crimped and connected to the cable conductors 1 and 2 using the crimp sleeve 5.6, and the telescopic main current conductor 9 is made of a flexible material. This method is easier to connect than the one that requires bending the expansion/contraction absorbing conductor with strong force.

In addition, the telescopic main current passage body 9, internal cooling pipe 7, conductor potential cylinder 10, etc. can be manufactured in the factory with pre-connected parts to the crimp sleeves 5 and 6, resulting in high quality stability and constant connection. Can be done under the characteristics.

Also, a cylinder 1 for conductor potential connected to cable conductors 1 and 2.
0 to cover the expandable main current path body 9 so that it has the same potential.

Therefore, even if there are irregularities on the circumferential surface of the expandable main current path body, or even if the surface irregularities change due to expansion and contraction, the electric field is not disturbed thereby, and stable insulation can be ensured.

Insulation between the conductor potential cylinder 10 and the sheath potential cylinder 12 is provided only at both ends by insulating tape 14, 15, and at the middle part by a liquid refrigerant.

Therefore, stable expansion and contraction of the sheath potential cylinder 12 is possible, and at the same time, the electric field is not disturbed by expansion and contraction, and a stress cone structure can be adopted for the transition from the insulating tape layers 14 and 15 to the liquid nitrogen layer 17. Therefore, stable insulation can be ensured.

Furthermore, in the present invention, the connecting portion is covered with the sheath potential cylinder 12, and by supporting this, the connecting portion can be stably fixed, so that it is less affected by vibrations and the like.

Although the present invention has been described above with reference to one embodiment, in place of the crimp sleeves 5 and 6, known means having the same effect as the crimp sleeves 5 and 6 may be used.

Further, in the above example, the internal cooling pipe 7 is made to expand and contract by fitting two cooling pipes together to create a sliding part, but it is also possible to extend and contract the internal cooling pipe 7 into one internal refrigerant path 1', 2', for example. Any known expansion/contraction method can be used, such as a method of fitting it in as shown.

Further, although this proposal has been described with reference to a cryogenic resistance cable using a normal conductor as a cable conductor, the present invention can also be applied to a superconducting cable using a superconductor such as niobium as a cable conductor.

In addition, the above example shows an example in which the present invention is applied to a type of cable in which refrigerant is placed inside the cable conductor for cooling.
It can also be applied to things that are cooled from the outside.

In this case, the internal cooling pipe 7 in the embodiment described above is used only for winding the telescopic main current path body.

As is clear from the above description, according to the present invention, it is possible to provide an expansion joint device for a cryogenic resistant cable that can absorb cable contraction during cooling in an electrically and mechanically stable state. This will make a major contribution to the realization of high-power cable transportation.

[Brief explanation of drawings]

Figures 1a and b are cross-sectional views of a conventional telescopic joint device in an expanded and contracted state; Figures 2a and b are longitudinal and partial vertical cross-sectional views showing an embodiment of the present invention in an expanded and contracted state;
The figure is a partial vertical sectional view showing the insertion structure of the third cylinder and the second cylinder. 1.2...Cable conductor, 1', 2'...
...Hollow refrigerant path, 3, 4...Insulator, 3', 4
'... Cable sheath, 5, 6... Crimp sleeve, 7... Internal cooling pipe, End...
Its sliding part, 9... Expandable main current path body, 10.
...Cylinder for conductor potential, 11...Sliding part,
12... Cylinder for sheath potential, 13a...
・First cylinder, 13b...Second cylinder, 13c...
...Third cylinder, 13d... Cable protection cylinder, 14, 15... Insulating tape, 16.17
... Sheath potential winding, 18 ... Liquid nitrogen insulating layer.

Claims (1)

[Scope of utility model registration request] A flexible main current path body is coiled around a tube having a stretchable part, and a conductor potential cylinder having a stretchable part is provided so as to surround its outer periphery. 1. A sheath potential having an extendable part surrounding the cable connection part so as to create an insulating gap between the extendable joint part of the cable conductor connected to the second connector and the outer peripheral surface of the conductor potential cylinder. After connecting both ends of the first and second connected cables, an insulating layer is provided across the cable sheaths at both ends and the cylinder for conductor potential, and then the cylinder for conductor potential and the sheath are connected to each other. A telescopic joint device for cryogenic cables in which the gap between potential cylinders is filled with liquid refrigerant for connection.