JP3032063B2 - Inspection method of superconducting power cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a superconducting power cable which can non-destructively check that a superconducting refrigerant such as liquid nitrogen or liquid helium is sufficiently impregnated in the superconducting power cable.

[0002]

2. Description of the Related Art FIG. 1 is a cross-sectional view showing a superconducting power cable, and FIG. A corrugated refrigerant pipe 1 is disposed at the center, and a cylindrical superconducting conductor 12 (not shown in FIG. 1) and an insulator are provided so as to be in contact with the outer surface of the central refrigerant pipe 1. 2
Are fitted. As shown in FIG. 1, the refrigerant pipe 1 has a circular cross section, extends in a wrinkle shape in the longitudinal direction of the cable, and has a trough and a ridge continuous on the outer surface of the pipe. In addition, the center of the circle of the cross section of the refrigerant pipe 1 moves spirally in the longitudinal direction of the cable.

[0003] As shown in FIG.
The valley portion 15 on the outer surface of the valley filling material 10 such as carbon cloth
Embedded by Thus, the central refrigerant pipe 1
Is smoothed in the axial direction.

In practice, semiconductive layers 11 and 13 are laminated on the inner surface and outer surface of the cylindrical superconducting conductor 12, and the insulator 2 is fitted on the outer semiconductive layer 13. In addition, a cylindrical shielding layer 3 is provided on the insulator 2 via a semiconductive layer 14.
Are fitted.

[0005] The shielding layer 3 is fitted with the inner tube 4, the cylindrical heat insulating layer 5 is fitted with the inner tube 4, and the heat insulating layer 5 is fitted with the outer tube 6. . The outer surface of the outer tube 6 is covered with an anticorrosion layer 7. The inner tube 4 and the outer tube 6 have a circular cross section like the central refrigerant tube 1, and the center of the circle moves spirally in the longitudinal direction of the cable.

[0006] The inside of the central refrigerant pipe 1 is an outward path 8 through which a refrigerant such as liquid nitrogen flows.
Is a return path through which the refrigerant flows.

In the superconducting power cable thus constructed, when a refrigerant such as liquid nitrogen as a superconducting medium flows through the outward path 8 and the return path 9, the superconducting conductor 12 is cooled by the refrigerant and exhibits superconducting characteristics. Then, when the superconducting medium 12 is energized, the resistance value becomes substantially zero, and electric power can be transmitted with extremely high efficiency.

When the superconducting power cable is impregnated with the refrigerant after the construction (cooling down), the insulator 2 is impregnated with the superconducting refrigerant. In this case, the relationship between the impregnation time and the breakdown voltage is checked in advance in accordance with the thickness of the insulator 2 and the impregnation pressure of the insulating material and the refrigerant, and the time when the breakdown voltage becomes constant is determined as the impregnation end time. In the impregnation process after the actual cable installation, the impregnation process is performed only for the impregnation end time.

[0009]

However, according to this conventional inspection method, it is possible to confirm the impregnation state at the time of manufacturing. There is a disadvantage that it cannot be checked.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a method of manufacturing a superconducting power cable capable of checking the impregnation state of a superconducting refrigerant after cable installation in addition to cable manufacturing. With the goal.

[0011]

According to the present invention, there is provided a method for manufacturing a superconducting power cable, comprising: a central refrigerant pipe through which a superconducting refrigerant flows; a superconducting conductor fitted with the central refrigerant pipe; Inspection of a superconducting power cable having an insulator fitted with a superconducting conductor and impregnated with the superconducting refrigerant, and an inner refrigerant pipe fitted with the insulator and forming a return path for the superconducting refrigerant with the insulator. In the method, a capacitance value between the inner refrigerant pipe and the central refrigerant pipe or the superconducting conductor is measured to determine whether or not the insulator is impregnated with the superconducting refrigerant.

[0012]

In the present invention, the capacitance value between the inner refrigerant pipe and the central refrigerant pipe or the superconducting conductor is measured. In this case, when the impregnation state of the superconducting refrigerant in the insulator is good, the measured capacitance value is high, and when the capacitance value is equal to or more than a predetermined value, it can be determined that impregnation is good. In other cases, impregnation failure can be determined.

[0013]

Embodiments of the present invention will be specifically described below.

The structure of the superconducting power cable itself is the same as the conventional one. However, in the present embodiment, at the time of re-cooling or the like, at the connection point between the power cable and the ground equipment shown in FIGS. 1 and 2, between the corrugated central refrigerant pipe 1 and the inner pipe 4, Connect a capacitance meter. Then, the capacitance value between the central refrigerant pipe 1 and the inner pipe 4 is measured, and when the measured value is equal to or larger than a predetermined capacitance value, the impregnation state of the insulator 2 or the like is determined. Judge as good.
On the other hand, if the measured capacitance value is less than the predetermined value, it is determined that impregnation is defective. In this manner, according to the present embodiment, it is possible to determine whether the impregnation state of the superconducting refrigerant such as liquid nitrogen or liquid helium is good after the cable is laid.

In other words, after the cooling down, when the impregnation of the cable, especially the insulator 2 with liquid nitrogen or liquid helium, is completed, the capacitance value between the central refrigerant pipe 1 and the inner pipe 4 is reduced. Is increased as compared to before the impregnation, or the capacitance value is stabilized, and the completion of the impregnation can be determined based on the detected value of the capacitance value.

The measurement of the capacitance value is not limited to the capacitance value between the inner pipe 4 and the central refrigerant pipe 1, and the capacitance value between the inner pipe 4 and the superconducting conductor 12 is measured. It may be measured.
This also makes it possible to determine the quality of impregnation.

[0017]

According to the present invention, the quality of the impregnation of the insulator or the like is determined by measuring the capacitance value between the inner pipe and the central refrigerant pipe or the superconducting conductor. Even later, the quality of the impregnation can be checked. For this reason, the present invention greatly contributes to improvement of superconducting cable maintenance, monitoring and inspection techniques.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a superconducting power cable.

FIG. 2 is a view showing a part of a longitudinal section of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1; Central pipe 2; Insulator 3; Shielding layer 4; Inner pipe 5; Heat shielding layer 6; Outer pipe 7; Anticorrosion layer 8; Refrigerant outward path 9; Refrigerant return path 12;

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Japanese Utility Model Showa 49-96465 (JP, U) Proceedings of the 1991 IEEJ National Convention, 12th volume, p. 12.18-12.19 (Issued March 10, 1992) (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01N 27/22-27/24 H01B 12/16 H02G 15/34 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A central refrigerant pipe through which a superconducting refrigerant flows, a superconducting conductor fitted with the central refrigerant pipe,
A superconducting power cable having an insulator in which the superconducting conductor is fitted and impregnated with the superconducting refrigerant, and an inner refrigerant pipe which fits the insulator and forms a return path for the superconducting refrigerant with the insulator. In the inspection method, the inner refrigerant pipe;
A method for inspecting a superconducting power cable, comprising: measuring a capacitance value between the central refrigerant pipe and the superconducting conductor to determine whether or not the insulator is impregnated with superconducting refrigerant.