GB/T 41640-2022 in English

VALID

Critical current measurement—Measurement of critical current and its uniformity along the length of 2G-HTS long tapes

Issued on:2022-10-12
Implemented on:2023-05-01
File Format:PDF
Delivery:Within 1 day

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Standard No:	GB/T 41640-2022
Document status:	VALID
Title in English:	Critical current measurement—Measurement of critical current and its uniformity along the length of 2G-HTS long tapes
Title in Chinese:	临界电流测量第二代高温超导长带临界电流及其沿长度方向均匀性测量
Language:	English
File Format:	Electronic (PDF)
Delivery:	Within 1 day
Issued on:	2022-10-12
Implemented on:	2023-05-01
Chinese Classification:	K10-Electrotechnical material and universal parts in general
Professional Classification:	GB-National Standard
Related Keywords:	critical current measurement measurement complete measurement system contact area ≥ strip width measurement implementation points current scanning measurement device
Related Topics:	critical range critical difference critical difference and critical range current measurement local critical current distribution critical relative height difference Extremely critical critical range current measurement Critical temperature test for zero toughness fluid critical velocity current electrode Toughness critical temperature test deuterium critical mass eva critical flue gas critical temperature critical reproducibility Zero toughness critical temperature test zero toughness critical temperature high temperature superconductivity Extremely poor criticality reproducibility + critical critical shunt High temperature interface instrument Criticality Boundary gauge length Marker critical extreme poor sex critical ratio critical difference critical temperature of aluminum high temperature superconductivity Very poor relative criticality polymer critical index superconducting motor magnetic critical index Critical solution plate thickness sex measurement quantum criticality dmso critical HTS+ Interface flow meter high temperature current current in english critical phenomenon quantum criticality Critical temperature for zero toughness critical solubility quantum criticality Relatively critical critical error critical temperature of water cutting edge interface Extremely poor criticality critical glow flow method critical properties Aluminum critical temperature Zero toughness critical temperature experiment water critical temperature boundary growth critical difference method Critical Current Density Tester critical mass of glycol How the critical point is measured critical signs Critical specific gravity critical amount of paint Critical parameter critical pah GBT41640 GB/T 41640-2022 electric current Immediately critical fluidization velocity Critical load current test method Temperature Uniformity Measurement

《GB/T 41640-2022临界电流测量第二代高温超导长带临界电流及其沿长度方向均匀性测量》由TC265（全国超导标准化技术委员会）归口，主管部门为中国科学院。

Introduction

Analysis of the core content of the standard

This standard specifies the dynamic transmission measurement method of the critical current (I_c) and its length-direction uniformity of second-generation high-temperature superconducting (2G-HTS) long ribbons in a liquid nitrogen environment, focusing on solving the problem that traditional short sample measurements cannot reflect the overall performance.

Key Technical Parameters

Parameter Category Requirement Range Special Restrictions

Strip Size Width 2-15mm
Thickness 0.1-0.5mm
Length ≥ 10m Not applicable to insulating coated strip

Electrical Properties I_c＜500A
n Value＞5 Current Capacity ≥ 1.5 Times I_c

Test Conditions Liquid nitrogen temperature 76.5-77.8K
Standard atmospheric pressure Local temperature rise needs to be monitored <1K

Requirements for measurement device

5.1 System composition

The complete measurement system includes:

Roll-to-roll system: constant tension control (strain <0.1%), guide wheel diameter ≥30mm

Cryogenic system: liquid nitrogen tank needs to completely immerse the four-lead component

Test system: DC source (stability 1%) + nanovoltmeter (resolution 1nV)

class=instrument>Protection system: Preheating and drying (50-150℃) + nitrogen protection

5.4 Electrode contact specifications

Roller electrode: Surface contact, three leads are required to monitor contact resistance

Plane electrode: Pressure ≤35MPa, contact area ≥ strip width

Measurement implementation points

6.3 Key steps

Sample preparation: Weld the guide strips (1-5cm) at the beginning and end, and it is recommended to use non-contact pre-inspection to locate defects

Cooling requirements: Liquid nitrogen immersion ≥3cm, start measurement after stabilization for 3-5 minutes

Current scanning:Constant rate current rising method (＞10s to I_c) or current rising-constant current-current rising method

Step detection:Step length 1-5m, overlap length L₆≥2L₅

7.1 Critical current criterion

Electric field criterion is preferred:

U_c = L₂×E_c (E_c=10μV/m or 100μV/m)

The slope of UI curve needs to be <0.3U_c/I_c, otherwise it is considered invalid

Technology evolution analysis

Compared with traditional Bi2223 strip, the ceramic properties of REBCO strip lead to:

Mechanical fragility: critical strain is only 0.45-0.7%, requiring strict tension control

Current transfer effect: L₃≥ strip width to avoid "climbing" phenomenon

Temperature sensitivity: a change of 1K in liquid nitrogen temperature causes a change of I_c of about 4.9A

The standard controls the measurement uncertainty of long strips to 10% (k=2) through multi-electrode configuration and dynamic stepping design

Implementation recommendations

9.3 Test report elements

I_c distribution diagram (column/dot)

Average value I_c, extreme value, standard deviation s

Voltage lead spacing L₂ and step length L_s

Abnormal section retest data

Operation precautions

⚠️ Burnt belt protection: It is recommended to use a braided sleeve to increase the electrode contact area and monitor the contact resistance temperature rise

⚠️ Data validity: When I_ci drops by ＞50%, it is necessary to retest and confirm immediately

More samples: DL/T 368-2010 JJG 21-2008 JC/T 2453-2018

Sample only — not a preview of GB/T 41640-2022

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Parameter Category	Requirement Range	Special Restrictions
Strip Size	Width 2-15mm Thickness 0.1-0.5mm Length ≥ 10m	Not applicable to insulating coated strip
Electrical Properties	I_c＜500A n Value＞5	Current Capacity ≥ 1.5 Times I_c
Test Conditions	Liquid nitrogen temperature 76.5-77.8K Standard atmospheric pressure	Local temperature rise needs to be monitored <1K