EN 61788-14:2010

Superconductivity - Part 14: Superconducting power devices - General requirements for characteristic tests of current leads designed for powering superconducting devices

IEC 61788-14:2010(E) provides general requirements for characteristic tests of conventional as well as superconducting current leads to be used for powering superconducting equipment.

Supraleitfähigkeit – Teil 14: Supraleitende Betriebsmittel – Allgemeine Anforderungen an charakteristische Prüfverfahren für Stromzuführungen für die Versorgung supraleitender Geräte

Supraconductivité – Partie 14 : Dispositifs de puissance supraconducteurs - Exigences générales concernant les essais caractéristiques des broches de courant conçus pour l’alimentation des dispositifs supraconducteurs

L'IEC 61788-14:2010 fournit les exigences générales pour les essais de caractéristiques d'amenées de courant classiques, ainsi que supraconductrices, destinées à être utilisées pour alimenter des matériels supraconducteurs. Les amenées de courant sont des composants indispensables des dispositifs supraconducteurs pour des utilisations pratiques telles que le matériel de diagnostic par IRM (Imagerie par résonance magnétique), les spectromètres à RMN (Résonance magnétique nucléaire), les dispositifs de croissance de monocristaux, le SMES (Stockage d'énergie magnétique supraconductrice), les accélérateurs de particules tels que Tevatron, HERA, RHIC et LHC, les appareils expérimentaux d'essai pour réacteurs à fusion nucléaire, tels que ToreSupra, TRIAM, LHD, EAST, KSTAR, W7-X, JT-60SA et ITER, etc., et des dispositifs supraconducteurs perfectionnés dans un futur proche dans des utilisations pratiques telles que les trains à sustentation magnétique (à supraconducteurs), les limiteurs de courant de défaut à supraconducteur, les transformateurs supraconducteurs, etc. Les principales fonctions des amenées de courant sont la fourniture de courants forts à des dispositifs supraconducteurs et la minimisation de la charge calorifique globale, ce qui inclut les pertes de chaleur entre la température ambiante et la température cryogénique et l'échauffement par effet Joule à travers les amenées de courant. À cet effet, les amenées de courant sont extrêmement efficaces pour diminuer la charge calorifique globale pour utiliser le composant supraconducteur haute température critique en tant que partie des amenées de courant. Mots clé: supraconductivité, TC90

Superprevodnost - 14. del: Močnostne naprave s superprevodniki - Splošne zahteve za značilne preskuse tokovnih vodnikov, načrtovanih za močnostne superprevodnike (IEC 61788-14:2010)

Ta del IEC 61788 podaja splošne zahteve za značilne preskuse tako konvencionalnih kot superprevodnih tokovnih vodnikov, ki se uporabljajo za močnostne superprevodnike.

General Information

• Status: Published
• Publication Date: 29-Jul-2010
• Withdrawal Date: 30-Jun-2013
• ICS: 29.050 - Superconductivity and conducting materials
• Technical Committee: CLC/SR 90 - Superconductivity
• Drafting Committee: IEC/TC 90 - IEC_TC_90
• Parallel Committee: IEC/TC 90 - IEC_TC_90
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 30-Jul-2010
• Completion Date: 30-Jul-2010
• Ref Project: SIST EN 61788-14:2010 - Superconductivity - Part 14: Superconducting power devices - General requirements for characteristic tests of current leads designed for powering superconducting devices (IEC 61788-14:2010)

Overview

EN 61788-14:2010 (IEC 61788-14:2010) defines general requirements for characteristic tests of current leads used to power superconducting devices. The standard covers both conventional (normal-conducting) and superconducting current leads - typically leads that connect room-temperature systems to cryogenic superconducting equipment and often include a high-temperature superconducting (HTS) section. The primary objective is to standardize test methods and reporting so manufacturers, test laboratories and end users can assess performance, compatibility and cryogenic heat impact reliably.

Key topics and requirements

The standard specifies the test items and general methods rather than prescriptive design details. Major technical topics include:

• Terms and definitions for current leads, heat leakage, heat load, rated current, gas-cooled and non-gas-cooled types, HTS sections.
• Structure inspection to verify mechanical and assembly integrity before electrical or thermal testing.
• Stress/strain tests to evaluate mechanical robustness under operational and installation conditions.
• Thermal property tests to measure heat leakage (at zero current) and heat load during current-carrying operation, focusing on minimizing heat transfer to the cryogenic bath.
• Rated current-carrying test to confirm thermal and electrical behaviour at specified operating current.
• Contact resistance and voltage drop tests to assess electrical losses and connection quality.
• High-voltage (insulation) tests to ensure dielectric coordination and safety per related insulation standards.
• Pressure drop and leak tightness tests where applicable for gas-cooled designs.
• Safety margin (quench) tests, reporting requirements and operational precautions.
• Informative annexes provide examples of typical current-lead configurations, HTS component test items and explanatory figures.

Applications and who uses this standard

EN 61788-14:2010 is intended for engineers and organizations involved in:

• Design and manufacture of current leads and HTS components
• Cryogenic and superconducting system integrators (MRI, NMR, SMES, particle accelerators, fusion testbeds, superconducting transformers, maglev, superconducting fault current limiters)
• Test laboratories and QA teams performing acceptance or type testing
• Procurement specialists specifying performance and safety requirements for superconducting power devices The standard helps reduce heat loads to cryogenic systems, verify electrical/thermal performance, and improve interchangeability and safety of current leads across applications.

Related standards

Relevant referenced documents include:

• IEC 60050-815:2000 (IEV - Superconductivity terminology)
• IEC 60071-1 (Insulation coordination)
• IEC 60137 (Insulated bushings >1 000 V) EN 61788-14:2010 aligns with the IEC 61788 series on superconductivity and complements other parts that address superconducting materials and components.

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.6SORãQHþQRVWQHSupraleitfähigkeit – Teil 14: Supraleitende Betriebsmittel – Allgemeine Anforderungen an charakteristische Prüfverfahren für Stromzuführungen für die Versorgung supraleitender Geräte (IEC 61788-14:2010)Supraconductivité – Partie 14 : Dispositifs de puissance supraconducteurs - Exigences générales concernant les essais caractéristiques des broches de courant conçus pour l’alimentation des dispositifs supraconducteurs (CEI 61788-14:2010)Superconductivity - Part 14: Superconducting power devices - General requirements for characteristic tests of current leads designed for powering superconducting devices (IEC 61788-14:2010)29.050Superprevodnost in prevodni materialiSuperconductivity and conducting materialsICS:Ta slovenski standard je istoveten z:EN 61788-14:2010SIST EN 61788-14:2010en01-oktober-2010SIST EN 61788-14:2010SLOVENSKI
STANDARD
EUROPEAN STANDARD EN 61788-14 NORME EUROPÉENNE
EUROPÄISCHE NORM July 2010
CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Management Centre: Avenue Marnix 17, B - 1000 Brussels
© 2010 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61788-14:2010 E
ICS 29.050
English version
Superconductivity -
Part 14: Superconducting power devices -
General requirements for characteristic tests of current leads designed
for powering superconducting devices (IEC 61788-14:2010)
Supraconductivité –
Partie 14 : Dispositifs de puissance supraconducteurs -
Exigences générales concernant
les essais caractéristiques des broches
de courant conçus pour l’alimentation
des dispositifs supraconducteurs (CEI 61788-14:2010)
Supraleitfähigkeit –
Teil 14: Supraleitende Betriebsmittel – Allgemeine Anforderungen
an charakteristische Prüfverfahren
für Stromzuführungen für die Versorgung supraleitender Geräte (IEC 61788-14:2010)
This European Standard was approved by CENELEC on 2010-07-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom.
Foreword The text of document 90/244/FDIS, future edition 1 of IEC 61788-14, prepared by IEC TC 90, Superconductivity, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 61788-14 on 2010-07-01. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent rights. The following dates were fixed: – latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement
(dop)
2011-04-01 – latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow)
2013-07-01 Annex ZA has been added by CENELEC. __________ Endorsement notice The text of the International Standard IEC 61788-14:2010 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following notes have to be added for the standards indicated: IEC 61788-3:2006 NOTE
Harmonized as EN 61788-3:2006 (not modified). IEC 61788-10:2006 NOTE
Harmonized as EN 61788-10:2006 (not modified). __________
- 3 - EN 61788-14:2010 Annex ZA
(normative)
Normative references to international publications with their corresponding European publications
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
NOTE
When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies.
Publication Year Title EN/HD Year
IEC 60050-815 2000 International Electrotechnical Vocabulary (IEV) -
Part 815: Superconductivity - -
IEC 60071-1 - Insulation co-ordination -
Part 1: Definitions, principles and rules EN 60071-1 -
IEC 60137 - Insulated bushings for alternating voltages above 1 000 V EN 60137 -
IEC 61788-14Edition 1.0 2010-06INTERNATIONAL STANDARD
Superconductivity –
Part 14: Superconducting power devices – General requirements for characteristic tests of current leads designed for powering superconducting devices
INTERNATIONAL ELECTROTECHNICAL COMMISSION UICS 29.050 PRICE CODEISBN 978-2-88912-006-2
– 2 – 61788-14 © IEC:2010(E) CONTENTS FOREWORD.3 INTRODUCTION.5 1 Scope.6 2 Normative references.6 3 Terms and definitions.6 4 Principles.7 5 Characteristic test items.8 6 Characteristic test methods.9 6.1 Structure inspection.9 6.2 Stress/strain effect test.10 6.3 Thermal property test.10 6.4 Rated current-carrying test.11 6.5 Contact resistance test.12 6.6 Voltage drop test.12 6.7 High voltage test.12 6.8 Pressure drop test.13 6.9 Leak tightness test.13 6.10 Safety margin test.14 7 Reporting.15 8 Precautions.15 Annex A (informative)
Supplementary information relating to Clauses 1 to 8.16 Annex B (informative)
Typical current leads.18 Annex C (informative)
Explanation figures to facilitate understanding of test methods.22 Annex D (informative)
Test items and methods for a HTS component.24 Bibliography.26
Figure B.1 – Schematic diagram of self-cooled normal conducting current leads.18 Figure B.2 – Schematic diagram of forced flow cooled normal conducting current leads.19 Figure B.3 – Schematic diagram of current leads composed of forced flow cooled normal conducting section and HTS section in vacuum environment.19 Figure B.4 – Schematic diagram of current leads composed of forced flow cooled normal conducting section and HTS section in GHe environment.20 Figure B.5 – Schematic diagram of current leads composed of LN2/GN2/GHe cooled normal conducting section and self-sufficient evaporated helium cooled HTS section.20 Figure B.6 – Schematic diagram of current leads composed of conduction cooled normal conducting section and HTS section.21 Figure C.1 – Schematic drawing of a temperature profile during the rated current-carrying test .22 Figure C.2 – Schematic drawing of a pressure dependency of the breakdown voltage in the Paschen tightness test.22 Figure C.3 – Schematic drawing of a time dependency of the voltage rise at the quench test .23
Table 1 – Characteristic test items and test execution stages for current leads.9 Table D.1 – Characteristic test items for a HTS component.24 SIST EN 61788-14:2010

61788-14 © IEC:2010(E) – 3 – INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
SUPERCONDUCTIVITY –
Part 14: Superconducting power devices –
General requirements for characteristic tests of current
leads designed for powering superconducting devices
FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non-governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user. 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter. 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any services carried out by independent certification bodies. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 61788-14 has been prepared by IEC technical committee 90: Superconductivity. The text of this standard is based on the following documents:
FDIS Report on voting 90/244/FDIS 90/250/RVD
Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all parts of the IEC 61788 series, published under the general title Superconductivity, can be found on the IEC website. SIST EN 61788-14:2010

– 4 – 61788-14 © IEC:2010(E) The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to the specific publication. At this date, the publication will be
• reconfirmed, • withdrawn, • replaced by a revised edition, or • amended. A bilingual version of this standard may be issued at a later date.
61788-14 © IEC:2010(E) – 5 – INTRODUCTION Current leads are indispensable components of superconducting devices in practical uses such as MRI diagnostic equipment, NMR spectrometers, single crystal growth devices, SMES, particle accelerators such as Tevatron, HERA, RHIC and LHC, experimental test instruments for nuclear fusion reactors, such as ToreSupra, TRIAM, LHD, EAST, KSTAR, W7-X, JT-60SA and ITER, etc., and of advanced superconducting devices in the near future in practical uses such as magnetic levitated trains, superconducting fault current limiters, superconducting transformers, etc. The major functions of current leads are to power high currents into superconducting devices and to minimize the overall heat load, including heat leakage from room temperature to cryogenic temperature and Joule heating through current leads. For this purpose, current leads are dramatically effective for lowering the overall heat load to use the high temperature superconducting component as a part of the current leads.
On the other hand, the current lead technologies applied to superconducting devices depend on each application, as well as on the manufacturer's experience and accumulated know-how. Due to their use as component parts, it is difficult to judge the compatibility, flexibility between devices, convenience, overall economical efficiency, etc of current leads. This may impede progress in the growth and development of superconducting equipment technology and its application to commercial activities, which is a cause for concern. Consequently, it is judged industrially effective to clarify the definition of current leads to be applied to superconducting devices and to standardize the common characteristic test methods in a series of general rules.
– 6 – 61788-14 © IEC:2010(E) SUPERCONDUCTIVITY –
Part 14: Superconducting power devices –
General requirements for characteristic tests of current
leads designed for powering superconducting devices
1 Scope This part of IEC 61788 provides general requirements for characteristic tests of conventional as well as superconducting current leads to be used for powering superconducting equipment. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
IEC 60050-815:2000, International Electrotechnical Vocabulary (IEV) – Part 815: Superconductivity
IEC 60071-1, Insulation coordination – Part 1: Definitions, principles and rules IEC 60137, Insulated bushings for alternating voltages above 1 000 V 3 Terms and definitions For the purposes of this document, the terms and definitions contained in IEC 60050-815:2000 as well as the following terms and definitions apply: 3.1
current lead
power lead
conductor to introduce electric current into a device with an insulation and a cooling channel especially when leading from room temperature to cryogenic temperature
[IEV 815-06-47] 3.2
normal conducting current lead
conventional current lead current lead made only of a normal conducting section 3.3
superconducting current lead current lead containing a superconducting section NOTE A superconducting current lead consists of a normal conducting section from room temperature to intermediate temperature and a superconducting section from intermediate temperature to cryogenic temperature. In this standard, the superconducting section is mostly made by a high temperature superconductor (HTS).
3.4
non-gas cooled type current lead current lead cooled by conduction cooling method SIST EN 61788-14:2010

61788-14 © IEC:2010(E) – 7 – 3.5
gas-cooled type current lead current lead cooled by a cooling gas NOTE In some cases, the gas cooling is made between cooling via gas flow inside the leads and (additional) convection cooling on the outside surface. 3.6
self-cooled current lead
vapour enthalpy cooled current lead current lead capably cooled by an evaporated gas generated by heat load from current leads into cryogen
3.7
heat leakage
non-current heat leakage heat conducted from higher temperature portion into lower temperature portion of the current lead at zero current operation without any Joule heating 3.8
heat load total heat induced into a cryogenic system through the current leads under current-carrying operation 3.9
rated current heat load heat load at a rated current operation 4 Principles The powering of superconducting equipment is made via components that provide the electrical link between the room temperature environment and the cryogenic temperature of the powered equipment. These components are called current leads. Since they operate in a gradient of temperature and they transport current into the cryogenic environment, they are one of the major sources of a heat leakage into the cryostat.
The current leads can be classified into two types: – normal conducting current leads, made entirely from normal conducting section. These are usually joined at their cold end to a superconducting (SC) bus or link leading to the device being powered;
– high temperature superconducting (HTS) current leads, which incorporate a section of HTS material. A normal conducting section is necessary to conduct the current from room temperature to the warm end of the HTS section. The latter must be maintained at a sufficiently low temperature to ensure that it remains superconducting for the maximum rated current of the lead. The cold end of the HTS section is usually joined to the device by a SC bus.
Depending on the cooling method, the leads can be either non-gas-cooled or gas-cooled. Both types of cooling methods can be used if the lead is subdivided into two, hydraulically separated, sections. If the device being powered uses low temperature superconducting (LTS) material, the link to the lead is usually via LTS cables or wires. Optimized, self-cooled normal conducting current leads conduct into the helium bath 1,1 W/kA [1]1) to 1,2 W/kA [2]. This value can be reduced substantially by using HTS material. HTS current ___________ 1) Figures in square brackets refer to the Bibliography. SIST EN 61788-14:2010

– 8 – 61788-14 © IEC:2010(E) leads have been extensively studied, designed and tested, and are already being integrated into large-scale systems [3] [4]. The design of a current lead is uniquely linked to the system within which it has to operate. The choice of materials, the cooling method, the geometry, the electrical characteristics and the admissible cryogenic consumptions are strongly influenced by boundary conditions imposed by the whole system. System requirements are electrical, cryogenic, and mechanical, and include the following: – maximum operating current, operation mode, current ramp rate, insulation voltage, circuit time constant, ambient magnetic fields; – cryogen availability, cryogen inlet/outlet temperature and pressure, admissible heat loads, time duration when the lead shall operate safely in case of failure of cryogen supply; – the volume available for integration, including mechanical support, vacuum insulation, and connection to the hydraulic and electrical interfaces. NOTE 1 The heat leakage for self-cooled current leads should make use of 1,2 W/kA in the case of large current capacities. NOTE 2 Typical current leads based on these principles are shown in Annex B. 5 Characteristic test items The following clauses describe the qualification tests that should be performed on a current lead at both room and cryogenic temperatures in order to verify its mechanical, electrical and thermal performance. It is assumed that the design of the current lead has been carried out in consideration of general versatility. Before application to an actual system, it is also necessary to do the optimization of the current lead according to the constraints imposed by each system. The characteristic test items shown in Table 1 should enable the user to verify if the current lead meets the specified requirements, and to judge if the test items meet the execution stage of the current lead. It is the responsibility of the user of this standard to select the appropriate tests according to Table 1 considering the boundary conditions of the current leads. SIST EN 61788-14:2010

61788-14 © IEC:2010(E) – 9 – Table 1 – Characteristic test items and test execution stages for current leads
Characteristic test execution stage
Characteristic test category Test items R&Da Catalogueb Receivec Structure inspection
Yes Yes 1 Mechanical characteristics Stress/strain effect test Yes
Non-current heat leakage test Yes Yes
2 Thermal
properties Rated current heat load test Yes
Yes
Rated current-carrying test
Yes Yes
Contact resistance test Yes
High voltage test Yes Yes
3 Electrical characteristics Voltage drop test Yes Yes
Pressure drop test with rated gas flow Yes Yes
4 Hydraulic characteristics Leak tightness test
Yes
Cryogen failure test Yes Yes
Quench test Yes
5 Safety margin characteristics Maximum pressure test Yes Yes
NOTE 4 Characteristic test items and methods for the components of HTS section are shown in Annex D. a “R&D” means the test stage for basic research or trial productions of current lead systems. b “Catalogue” means the test stage for performed R&D or mass production of the current leads. c “Receive” means the test stage after installation of the current lead system in the site.
6 Characteristic test methods The test methods listed here are recommendations. The user may also select other test methods if required by specific applications or boundary conditions. 6.1 Structure inspection 6.1.1 Purpose This test shall inspect dimensions, applicable materials, structure, structural state and so on as well as the thermal insulation property and leak tightness of the container in the target system. 6.1.2 Methods The structure inspection test at room temperature shall inspect dimensions, applicable materials, structure, structural state and so on. The structure inspection test at low temperature shall inspect visually the state of frost forming on the surface of a cryostat filled with cryogen or connected to a refrigerator. As for cryostats with the vacuum thermal insulatin
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