JP2000331547A - Thermal strain removal method for HTS cable - Google Patents

Abstract

(57) [Summary] [Problem] To keep the amount of thermal strain of a conductor within an allowable value, prevent excessive tensile force from being applied to the conductor, prevent the critical current of the conductor from lowering, and prevent the performance from deteriorating. Provided is a method for removing thermal distortion of a superconducting cable. SOLUTION: An offset portion is formed on both sides of a connection portion of a high-temperature superconducting cable, a thermal strain amount of a conductor of the high-temperature superconducting cable is monitored, and the offset amount is adjusted according to the monitored thermal strain amount of the conductor. To keep the thermal strain of the conductor within the allowable range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing thermal distortion of a conductor of a high-temperature superconducting cable.

[0002]

2. Description of the Related Art A superconducting cable is used by flowing a cooling medium through the cable for cooling the conductor. However, when the cooling medium is introduced into the cable or when the cooling medium is discharged from the cable, the temperature difference is large. Therefore, the conductor receives thermal strain.

A metal-based superconducting cable using niobium titanium, niobium tin or the like as a conductor and helium as a cooling medium is critical even if a tensile strain is applied to the conductor due to heat shrinkage during cooling because the metal-based conductor is resistant to distortion. The current does not decrease and the performance does not decrease. Therefore, there was no need to provide a mechanism or the like for absorbing thermal expansion and contraction of the conductor.

[Problems to be solved by the invention]

However, in a high-temperature superconducting cable using bismuth or yttrium as a conductor and liquid nitrogen as a cooling medium, when the conductor is vulnerable to distortion and a connection similar to that of the metal-based superconducting cable is formed, When tensile strain is applied to the conductor due to thermal shrinkage, the critical current of the conductor decreases,
There is a problem that performance is reduced.

[0005]

SUMMARY OF THE INVENTION The present invention provides a method for removing thermal distortion of a high-temperature superconducting cable in a high-temperature superconducting cable, in which the amount of thermal distortion of a conductor is kept within an allowable value to prevent performance degradation. The first feature is that offset portions are formed on both sides of the connecting portion of the high-temperature superconducting cable, the amount of thermal distortion of the conductor of the high-temperature superconducting cable is monitored, and the amount of offset is determined according to the amount of thermal distortion of the monitored conductor. To maintain the amount of thermal strain of the conductor at an allowable value.

A second feature of the present invention is that a tension member resistant to distortion is provided along a cable core of a high-temperature superconducting cable, and offset portions are formed on both sides of a connecting portion of the high-temperature superconducting cable. By displacing the position of the connection portion by the thermal expansion and contraction of the tension member, the thermal strain of the conductor is kept within an allowable value.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic explanatory view of a method for removing a thermal strain which realizes the first feature of the present invention. In the drawings, 1 is a manhole, 2 is a cable conduit, 3 is a high-temperature superconducting cable containing a superconducting cable core 5 inside, 4
Is a connecting portion of the high-temperature superconducting cable 3 installed in the manhole 1, and offsets A are formed on both sides of the connecting portion 4. Reference numeral 6 denotes a monitor such as a strain gauge that measures the amount of thermal strain provided on the cable core 5 of the high-temperature superconducting cable 3. Reference numeral 7 denotes a hydraulic jack that displaces the connecting portion 4 according to the amount of thermal strain measured by the monitor 6. is there.

Since the thermal contraction occurs when the cable is cooled, the relationship between the thermal distortion of the conductor during the cooling and the thermal distortion of the cable core surface is examined in advance. Then, while monitoring the amount of thermal contraction of the conductor with a strain gauge or the like during cooling of the cable, the hydraulic jack is driven to displace the position of the cable connecting portion to adjust the offset amount, and to actively absorb the thermal expansion and contraction of the conductor. And the amount of thermal strain is kept within an allowable value.

FIG. 2 is an explanatory diagram of an example of a circuit for implementing the thermal distortion removing method of FIG. The same reference numerals as those in FIG. 1 indicate the same parts. A voltage output continuously measured by a monitor 6 such as a strain gauge installed on a cable core 5 in the cable connection section 4 is introduced into an arithmetic unit 11 via a strain amplifier 10. The arithmetic unit
And the voltage output of the monitor 6, 11, compressive strain allowable value of the voltage (negative) V ₁ and tensile strain tolerance of the voltage (positive) as compared to V _2, in the case of V <V _1, then up the hydraulic hydraulic jack instructs the up, V> down the hydraulic pressure in the case of V ₂ and a hydraulic jack down
Command.

In the case of a hydraulic pressure up command, the pump 12 is driven to send the oil in the oil reservoir 13 to the hydraulic jack 7 to extend the hydraulic jack 7, and in the case of a hydraulic pressure down command, the valve 14 is opened and the hydraulic jack 7 is opened. The hydraulic jack 7 is returned to the oil reservoir 13 to contract. As described above, the position of the connecting portion 4 is displaced by the operation of the hydraulic jack 7 and the offset portion A is adjusted to actively absorb the thermal expansion and contraction of the conductor and maintain the amount of thermal strain within an allowable value. No excessive pulling force is applied.

FIG. 3 is a schematic explanatory view of an example of a high-temperature superconducting cable used in a thermal strain removing method for realizing the second feature of the present invention. As shown in the drawing, the center of the three-core twisting of the cable core 5 housed inside the high-superpower cable 3 is strongly resistant to distortion with respect to a cooling medium such as liquid nitrogen such as nylon or FRP. Large material tension member
Keep 15 along.

As shown in FIG. 4, offset portions A are formed on both sides of the connecting portion 4 of the high-temperature superconducting cable 3 in which the tension member 15 made of a material having a high resistance to distortion and a large amount of distortion is applied to the cable core 5. And lay it down. When such a high-temperature superconducting cable is cooled, the tension member 15 along the cable core 5 also contracts simultaneously with the contraction of the conductor, and the position of the connection box 4 is displaced to absorb the contraction strain applied to the conductor, and Is kept within the allowable value, and no excessive tensile force acts on the conductor.

[0013]

As described above, according to the method for removing thermal strain of a high-temperature superconducting cable according to the present invention, the position of the cable connection is actively or passively displaced to adjust the offset amount on both sides of the connection. Thus, the amount of thermal strain applied to the conductor can be kept within an allowable value, and no excessive tensile force acts on the conductor.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory diagram of a thermal distortion removing method for realizing a first feature of the present invention.

FIG. 2 is an explanatory diagram of an example of a circuit used in the embodiment of FIG. 1;

FIG. 3 is a schematic explanatory view of an example of a high-temperature superconducting cable used for a second feature of the present invention.

FIG. 4 is a schematic explanatory view of a thermal strain removing method using the high-temperature superconducting cable of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Manhole 2 Cable conduit 3 High-temperature superconducting cable 4 Connection part 5 Cable core 6 Monitor 7 Hydraulic jack A Offset part 10 Strain amplifier 11 Computing device 12 Pump
13 Oil reservoir 14 Valve 15 Tension member

Claims (2)

[Claims] 1. An offset portion is formed on both sides of a connection portion of a high-temperature superconducting cable, the amount of thermal distortion of a conductor of the high-temperature superconducting cable is monitored, and the offset amount is adjusted according to the monitored amount of thermal distortion of the conductor. A method for removing thermal strain from a high-temperature superconducting cable, wherein the thermal strain of the conductor is kept within an allowable value by performing the method. 2. A high tension superconducting cable has a tension member resistant to distortion along a cable core thereof, and offset portions are formed on both sides of a connection portion of the high temperature superconducting cable. A method for removing thermal strain from a high-temperature superconducting cable, wherein the amount of thermal strain of a conductor is kept within an allowable value by displacing the position of the connection portion.