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Date of Issue: February 16, 2015

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KSP, Kawasaki, Kanagawa 213-0012 Japan Tel:+81-44-850-1612, Fax:+81-44-850-1613

Contents:

Topics: What’s New in the World of Superconductivity
Feature Article: Progress in Superconducting Power Equipment Technology-The Development of Superconducting Power Equipment Technology at Furukawa Electric-Progress in the Technology Development of High-current Superconducting Cables-Cable-related Technology- 66kV 5kA-class Yttrium-based High Temperature
Superconducting Cable-Long-term Demonstration Results of High-temperature Superconducting Cables

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This work was subsidized by JKA using promotion funds fromKEIRIN RACE
http://ringring-keirin.jp

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Date of Issue: February 16, 2015

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What’s New in the World of Superconductivity초전도 뉴스 –세계의 동향超导新闻-世界的动向-chāo dǎo xīnwén

- shìjiè de dòngxiàng-

Yutaka Yamada, Principal Research Fellow
Superconductivity Research Laboratory, ISTEC★News sources and related areas in this issue►Basics기초 基础[jīchǔ]New High Temperature Superconductor, Tc=190K?
Max-Plank Institute and Nature (12 Dec, 2014)
For over 30 years, researchers have focused on cuprate room-temperature superconductors, which can
carry currents without energy loss up to temperatures of 164K (-109 ˚C). However, researchers havedemonstrated that hydrogen sulphide exhibits superconductivity at 190K (–83 ˚C) when it is subjected tohigh pressures, similar to those found at the Earth’s core.
Mikhail Eremets working at the Max Planck Institute for Chemistry in Mainz, Germany, placed a tiny sample

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of hydrogen sulphide between the tips of two diamond anvils and then measured how the material’s
electrical resistance changed as the system was cooled towards absolute zero. They discovered that theresistance dropped suddenly at around 190K under a pressure of 1.8 million atmospheres, indicating a
superconducting transition. The researchers also report having observed a much lower transition
temperature (90 K) when they exchanged heavier sulphur deuteride for sulphur hydride. They stated thatheavier atoms would impede superconductivity by reducing crystal vibrations. Their findings are available
online on arXiv, posted December 1.
The latest research builds on the work of Neil Ashcroft, a physicist at Cornell University in Ithaca, New York,
who studied the superconducting potential of hydrogen compounds. Particularly, it aims to investigate
recent theoretical predictions by a Chinese research team who predicted that hydrogen sulphide should
remain superconducting up to about 80K under a pressure of 1.6 million atmospheres. The electrons in the
Cooper pairs are squeezed together under such high pressure, making them less liable to be destroyed bythermal fluctuations.
"If the result is reproduced, it will be quite shocking. It would be a historic discovery", says Robert Cava, asolid-state chemist at Princeton University in New Jersey. It is hoped that the BCS theory can shed light on
the search for other kinds of high-temperature superconductors, particularly in materials containing lightelements such as hydrogen since they generate more rapid vibrations that create stronger bonds between
electron pairs. If other groups confirm the findings, then these findings signify a huge increase in the criticaltemperature – the current record being 39 K, measured in MgB2. Alexander Gurevich, a theorist at Old
Dominion University in Norfolk, Virginia, remains cautious and states that the authors have yet todemonstrate one of the hallmarks of superconductivity, known as the Meissner effect. He notes, “I do hopethat this work will stimulate other groups to reproduce this experiment promptly”.
Eremets and his colleagues say that it might now be possible to find high critical temperatures in otherhydrogen-containing materials, such as carbon-based fullerenes or aromatic hydrocarbons. However, Cava
adds that it is still too early to consider possible applications.
Source:”Superconductivity record breaks under pressure”(12 Dec, 2014) Nature News by Edwin Cartlidge and Nature magazine
http://www.nature.com/news/superconductivity-record-breaks-under-pressure-1.16552
Siemens (2014年12月18日)
Author of the paper: A. P. Drozdov (Max-Planck Institut, Germany) m.eremets@mpic.de

Short-time but Higher Tc at Room Temperature?
Max-Planck Institute (3 Dec, 2014)
In 2013, an international team working with the Hambrug-based, Max Planck researcher Andrea Cavalleri,discovered that when YBCO is irradiated with short infrared laser pulses it briefly becomes superconducting
at room temperature – albeit for only a few millionths of a microsecond. Physicists suggested that the laser
pulses modified the coupling between the double layers in the crystal, causing individual atoms in the
crystal lattice to shift briefly and thus enhance the superconductivity. The precise mechanism remained
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unclear until the researchers conducted an experiment using the world’s most powerful X-ray laser based at
LCLS in the USA. Their findings showed that the infrared pulse not only caused the atoms to oscillate, but
had also shifted their position in the crystal and briefly making the copper dioxide double layers thicker by
two picometres. This in turn increased the quantum coupling between the double layers to such an extent
that the crystal became superconducting at room temperature for a few picoseconds.
This Hamburg team has made crucial contributions, which has now been able to present a possible
explanation of the effect in the journal, Nature. The findings could assist in the development of materials,
which become superconducting at significantly higher temperatures. If complex cooling were no longer
necessary, it would mean a breakthrough for this technology.
Source: “Superconductivity without cooling”(3 Dec, 2014) Research News
http://www.mpg.de/8785897/superconductivity-room-temperature
Contact: Roman Mankowsky, roman.mankowsky@mpsd.mpg.de

Search for Higher Tc Mechanism
Swiss Federal Institute of Technology Lausanne (EPFL) (18 Dec, 2014)
Intense research is ongoing to exploit the physics of cuprates in the hope that we can develop
room-temperature superconductors. Cuprates offer great promise for achieving superconductivity at hightemperatures (-120 °C). Scientists from EPFL have employed a cutting-edge technique to reveal the way
cuprates become superconductors.
Conventional superconductors conduct electricity with no electrical resistance under temperatures nearing
absolute zero (−273.15 °C or 0 Kelvin). The electrons in the material form “Cooper pairs”, and only when
the atoms vibrate and create an attractive force between the electrons. However, cuprate superconductors
are electrically insulating at normal temperatures and Cooper pairs do not form. The question here is how
does superconductivity arise in cuprates?
A research team led by Marco Grioni at EPFL, has used a cutting-edge spectroscopic technique to explore
and provide a novel understanding of superconductivity in cuprates. The scientists employed Resonant
Inelastic X-ray Scattering, to interrogate the electronic structure of cuprates as it transitions into being a
superconductor. Grioni says, “Normally, superconductors hate magnetism. Either you have a good magnet
or a good superconductor, but not both. Cuprates are very different and have really surprised everyone,
because they are normally insulators and magnets, but they become superconducting when a few extra
electrons are added by gently tweaking its chemical composition.” Cuprates do not lose their magnetic
properties when they become superconducting, and Grioni believes that their findings could play a majorrole in the appearance of superconductivity. Their research outcome is published in Nature
Communications.
Source:” Electron spin could be the key to high-temperature superconductivity”(18 Dec, 2014) News Mediacom
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http://actu.epfl.ch/news/electron-spin-could-be-the-key-to-high-temperature/
Contact: Nikolaos Papageorgiou, n.papageorgiou@epfl.ch►Power Application

전력응용电力应用 [diànlì yìngyòng]Current Limiter for Renewable Energy Application
Siemens (18 Dec, 2014)
Large loads of renewable or other decentralized energies can produce short circuits in power supplies
operating in medium-voltage power grids. To address problems endangering power supplies, Siemens are
installing a resistive-type superconducting fault current limiter (SFCL) at Stadtwerke Augsburg, themunicipal utility in Augsburg, Germany. The project, abbreviated as "ASSIST," is being sponsored by theBavarian State Ministry for Economic Affairs and Media, Energy and Technology, under the Bavaria's
Innovative Energy Technologies and Energy Efficiency (BayINVENT) Program. The European Patent
Office (EPO) has already granted Siemens several key patents for the technologies used in resistive
superconducting fault current limiters. Development work and installation of the medium-voltage power grid
utility will be completed by the end of 2015.
Superconducting fault current limiters can limit short-circuit currents in power transmission and distribution
grids very quickly, thereby realizing reliable grid operation even under difficult conditions. The grids can also
resume normal operation without additional measures soon after a short cooling period. Unlike today’s
conventional short-circuit limiting reactors with a constant high resistance, superconducting fault current
limiters also exhibit another advantage that they are "invisible" to the grid during normal operation since they
have no electrical resistance. Superconducting fault current limiters also allow several different power
sub-grids to be linked, thereby increasing operational security and grid stability and eliminating the costs
associated with frequently replacing or upgrading electrical components.
Dr. Tabea Arndt, head of Superconducting Components and Applications at Siemens Corporate
Technology is quoted as saying, "With our innovative partner, Stadtwerke Augsburg, we have a power utility
where we can demonstrate how this advanced technology can help master the challenges of the energy
transition and grid upgrades successfully." Jürgen Völkel, technical director of Stadtwerke Augsburg, states,"Powerful plants for renewable energies (EEG plants) must be connected to the grid via efficient fault
current limiters to protect electrical components."
Source:”Siemens to use superconductors in building the power grid of the future in Augsburg”(18 Dec, 2014) Joint Press Release
http://www.siemens.com/press/en/pressrelease/?press=/en/pressrelease/2014/corporate/pr2014120086co
en.htm&content[]=Corp
Contact: Mr. Harald Hassenmuller, herald.hassenmueller@siemens.com

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Superconductivity Web21
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KSP, Kawasaki, Kanagawa 213-0012 Japan Tel:+81-44-850-1612, Fax:+81-44-850-1613►Electronics

엘렉트로닉스

电子应用 [diànzǐyè yìngyòng]New Superconducting Supercomputer
Office of the Director of National Intelligence (IARPA) (9 Dec, 2014)
Officials at the Intelligence Advanced Research Projects Activity (IARPA), part of the Office of the Director of
National Intelligence, stated on Dec. 3 that they had awarded three research contracts to support the firstphase of the Cryogenic Computing Complexity (C3) program. According to their announcement, significant
technical obstacles had previously prevented the exploration of superconducting computing, however,recent innovations had created foundations for potential breakthroughs to be made in this field.
The initial aims of the three-year C3 program are for researchers to develop the critical components for the
memory and logic subsystems and plan the prototype computer, ultimately developing a small-scale
supercooled supercomputer prototype that would use exponentially less power and floor space. The federal
government has been developing an exa-scale supercomputing system, potentially capable of 1 exaflop
floating point operations per second, by 2020, equivalent to 50 of the DOE’s current Titan systems.
Exascale computing would allow intelligence agencies to decipher ever-stronger encryption algorithms andbe able to analyze truly big data.
The contract involves teams led by IBM, Raytheon BBN Technologies and Northrop Grumman. It is highly
anticipated that the USA will become the lead as the first nation to break the exaflop barrier insupercomputing. Marc Manheimer, a C3 program manager at IARPA, said the awards are part of a
two-phase process for the development of greater-performing replacements to the federal government's
current range of supercomputers. He estimated that a supercooled machine would provide 100 petaflops of
performance for about 200 kilowatts of electricity, theoretically deliver five times the performance for 1/40thof the power in a much smaller footprint compared to Titan system. IARPA anticipates seeking further
proposals in the third year of the first phase for further development.
Source:”IARPA awards contracts for supercomputer development”(8 Dec, 2014) IARPA in the NEWShttp://www.iarpa.gov/index.php/newsroom/iarpa-in-the-news/2014?start=10
Contact: Federal Computer Week, mrockwell@fcw.com

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Feature Article: Progress in Superconducting Power Equipment
Technology-The Development of Superconducting Power Equipment Technology at
Furukawa Electric
Shinichi Mukoyama, Director
Power & System Laboratories
Furukawa Electric Co., Ltd.
Yttrium-based superconducting coated conductors (2G HTS
wires) characteristically can maintain high critical currents inhigh magnetic field environments. Their utilization is anticipatedfor realizing low costs due to the reduced consumption of rareearth metals. In fact, several years ago AMSC and Superpowerin the USA were the only commercial manufacturers of 2G HTS
wires, however more companies, including Fujikura in Japan,
have recently started commercial sales. With regards to wire
performance, 500m-class wires exceeding 400 A/cm
characteristics are being traded on the market and leading tobuoyant application research studies. At Furukawa Electric forexample, the application development of high-performance 2G
HTS wires is progressing to perform feasibility assessments ofsuperconducting cables, power equipment apparatus flywheels
and wind power turbines applications.

Demonstration trials of 275kV 3kA
30m-long superconducting cable

1. The development of superconducting cables
The development of a 275kV 3kA superconducting cable, exhibiting the world’s highest voltage capability 1)
has concluded its month-long current trial at the Shenyang Furukawa Cable Co., Ltd. in Shenyang city,
China, during the final year (2013) of its demonstration study. The cable was returned to Japan to undergo
remaining evaluation trials (a cable health check and current trial performed by breaking up the cable).
Other facilities such as the liquid nitrogen circulation system, power supplies and transmission facilities, andsuperconducting cable testing terminals still remain in place at Shenyang Furukawa. Thus, if the cablereturns to China, testing can resume promptly. A project 2) launched this year actually plans to evaluate
cable stability/reliability and involves short circuit trials, evaluating the loss of vacuum in the insulated pipe,
the cable behavior and potential impact to the liquid nitrogen circulation system under a variety ofproblematic scenarios.
2. The development of flywheels
Power generation derived from natural energies such as wind turbines and solar photovoltaics produces
output power fluctuations due to temporal instability characteristics of natural energy sources, which canlead to unstable grid frequencies. The development of the next-generation superconducting flywheels iscurrently ongoing, led by Furukawa Electric, Railway Technical Research Institute, KUBOTEK, MIRAPRO,

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and Yamanashi prefecture 3). This superconducting flywheel comprises of superconducting magnets
fabricated from YBCO bulk superconductors and 2G HTS wires, allowing non-contact levitation of the
flywheel producing high rotational speeds. This technology can thus eliminate losses due to bearing friction,
which have been a weakness of flywheels until now, with no requirements of associated regular
maintenance and replacement. Eventually, a rotational speed of around 6000rpm for a 10 ton-classflywheel can be realized. Project deliverables include the development of superconducting magnetic
bearings and a 300 kW, 100 kWh-class flywheel energy storage systems comprising of such bearings. A
finalized flywheel energy storage system will be installed at the Mount Komekura photovoltaic power plant
belonging to Yamanashi Prefectural Enterprise Bureau and grid-connection demonstrations are planned
later.
3. The development of superconducting wind power generators
Wind power generators are symbolic of power generation utilizing natural energy sources. The trend now is
towards developing larger-scale wind turbines and increasing the numbers of offshore installations that
present better wind conditions, and from the viewpoint of construction cost ratio per unit of power generated,
this further reduces the cost associated with power generation. In particular, since a 10MW-class ultra
large-scale wind turbine has difficulty as a ground-based installation due to its huge size an offshore
installation is under investigation. Furukawa Electric, in collaborations with National Institute of Advanced
Industrial Science and Technology and Mayekawa MFG, has progressively undertaken feasibility studies
involving a superconducting 10MW-class ultra large-scale wind turbine 4). The generator rotor comprises ofan iron core and a superconducting magnet fabricated from 2G HTS wires, allowing the power unit design
to be compact and lightweight, which otherwise would occupy a large space within the nacelle. Future
research development plans involve the fabrication of a life-size single-unit racetrack coil and cooling testing,which aims to address issues associated with a superconducting rotor, an important component for thesedemonstration studies.
The author believes that power equipment can be categorized as three technological applications; “powertransmission”, “power storage”, and “power generation”. Thus, “superconducting cable”, “flywheel” and“wind turbine”, in that order, can be promising superconducting power equipment applications, andFurukawa Electric is best placed to advance the development and realization of practical systems incollaboration with joint developers including NEDO.
Reference:
1) “Technology development of Yttrium-based superconducting power equipment” commissioned by the
Energy Conservation Technology Department, NEDO (2008-2012)
2) “Demonstration studies of stability/reliability of next-generation transmission systems” promoted by the
Energy Conservation Technology Department, NEDO (2014-2016)
3) “Technology development of reliable/low cost large-scale energy storage systems” promoted by the
Smart Community Department, NEDO (2011-2015)
4) “R&D projects for practical applications of wind turbines: Research studies into 10 MW-class wind turbine”
commissioned by the New Energy Technology Department, NEDO (2013-2014)

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February 2015

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Feature Article: Progress in Superconducting Power Equipment
Technology-Progress in the Technology Development of High-current
Superconducting Cables
Takato Masuda
Superconductivity Technology Department
Sumitomo Electric Industries, Ltd.
Tokyo Electric Power Company, Sumitomo Electric Industries, and MAYEKAWA MFG have progressed the“High Temperature Superconducting Cable Demonstration Project”, commissioned by the New Energy andIndustrial Technology Development Organization (NEDO). The project commenced on 29th October 2012,and demonstrated the operational characteristics of a superconducting cable connected to an actual grid.
The cable has accomplished a year-long grid operation on 25 December 2013, and realized continuous
operation with no significant problematic issues reported. Thus, the stability and reliability of thesuperconducting cable has been successfully verified.
As part of the evaluation trials, the critical current characteristics of the cable were measured by ascheduled separation from the grid during operation. The critical currents were also measured after thetrials to assess the cable characteristics. There were no measurable changes before and after gridconnection. Measurements of partial electrical discharge were taken randomly during the operational period
and with no signal detected thereby validating the favorable electrical insulating characteristics throughout.
Thermal data characteristics of the cable have been collected over four seasons. In direct sunshine thesurface temperature of the exposed parts on the ground increased significantly, which then tended to
produce increases in heat leakage. It was confirmed that a light-shielding coating applied to the parts
exposed to direct sunlight was effective. The cable terminal area having a large surface area was more
prone to vacuum degradation due to outgassing during increases in temperature. The situation was
however addressed by drawing a vacuum along the way.
The cable operational characteristics proved favorable during grid connection and the results verified
normal operation throughout. Now, our research team plans to investigate the cable characteristics under anumber of scenarios involving incidents at grids, which can potentially occur when the cable is operated forthe long term in practical transmission lines. Thus, superconducting cable reliability and recovery measuresduring incidents are currently being investigated under a new NEDO project entitled, “Demonstration
studies of the stability/reliability of next-generation transmission system,” which launched in July last year.
As part of this project, Sumitomo Electric plans to investigate the superconducting cable behavior undervarious scenarios including short-circuit faults, ground faults, extensive damage etc, together withverification tests to determine effects to ancillaries, as well as explore incident-recovery measures. The
author will continue his efforts towards the realization of practical superconducting cables.

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February 2015

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Feature Article: Progress in Superconducting Power Equipment
Technology-Cable-related Technology66kV 5kA-class Yttrium-based High Temperature Superconducting
Cable
Kazuo Watanabe, Executive Research Scientist
Superconductor Business Development Department
New Business Development Center
Fujikura Ltd.
Fujikura’s technology related to high-temperature superconducting cable is introduced herewith. Fujikura
has intensively developed Y-based coated conductors, employing its own Ion Beam Assisted Deposition(IBAD) and Pulsed Lase Deposition (PLD) techniques for their fabrication. An appearance of a Y-based
coated conductor is shown in Figure 1, with Table 1 listing the typical examples of wire products line-ups.
Currently, the critical currents (Ic) of standard products measured at liquid nitrogen (77 K) are over 500 A per
10mm-width (over 250 A per 5 mm-width). IBAD-PLD fabricated wires exhibiting high Ic characteristics of
600 A/cm-w (@77 K,s.f.) were manufactured as cables for the first time under a NEDO project (April 2012–
February 2013), which successfully demonstrated the high current/low AC loss characteristics asanticipated. Figure 2 shows the configuration of a 66 kV 5 kA-class Y-based superconducting cable thatwas designed and fabricated. Conductors and shield wires are all 4mm in width and exhibit high Ic
characteristics of 240 A/4mm-w(@77 K, s.f.). Figure 3 shows the entire view of the facilities used for thecurrent loading test. A demonstration cable system approximately 22 m-long, having terminal joints andcooling testing facilities was constructed at the Fujikura Sakura Plant to verify AC transmission
characteristics. The results from the test confirmed the current properties as designed, with around 98 % of
the current being induced in the superconducting shield layer during current loading test. Also, at liquid
nitrogen temperatures of 77 K it was established that the AC loss at 5000 A was sufficiently low comparedto the targeted value of 2.0 W/m (@5kArms). At 67 K, a reduction of half the targeted loss value was also
realized.
Table 1 Product line-ups of Y-based superconducting coated conductors

Model NoYSCSC05
FYSCSC10

Wirewidth

Thickness

(mm)

(mm)

5
10

0.16
0.21
0.16
0.21

Cu
Metal
Criticalstabilizer
substratecurrent(A)layer(@77K,
(μm)
(μm)
s.f.)
75
75
> 250
100
100
> 250
75
75
> 500
100
100
> 500

Fig. 1 Appearance of a Y-based coated conductor

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Items

Specifications

FormerCopper wires

20mmφSuperconductive layer

4-layer, all 4mm-width wires(Ic=14 kA)

Ic=240 A/4 mm-wide(77 K,s.f.)

Insulation layer

Craft papers (6mm-thickness)

Superconductive shielding layer

2-layer, all 4mm-width wires(Ic=12.7 kA)

Ic=240 A/4 mm-wide(77 K,s.f.)

Copper shield layer

Copper tapes, 44 mmφProtection layer

Non-woven fabric tapes, 45 mmφ

Thermal insulation pipe

Double stainless steel corrugated pipes
Vacuum thermal insulating method

Anticorrosion layerPE

114mmφFig. 2 Appearance and structural dimensions of Y-based superconducting cable

Fig. 3 Current loading test line for superconducting cable

As mentioned above, the targeted high current/low loss characteristics at liquid nitrogen temperatures of
77K were successfully realized for the first time and are suitable for practical use. It was also possible to not
only verify the possibilities to reduce loss by reducing load factors associated with high Ic but also regulate
the temperature parameters for designing a cooling system applicable for practical transmission lines. In the
future, the author anticipates that with the advantageous outcomes achieved superconducting cableattributes including low voltage high currents (large capacity) and low loss will be further enhanced,
eventually leading to a compact cable system.
This research was undertaken as part of the “Technology Development of Yttrium-based Superconducting
Power Equipment”, commissioned by the New Energy and Industrial Technology Development
Organization (NEDO).
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February 2015

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Feature Article: Progress in Superconducting Power Equipment
Technology-Long-term Demonstration Results of High-temperature
Superconducting Cables
Osamu Maruyama,
Superconductivity Technology Group, R&D CenterTokyo Electric Power Company

Cur rent [kA] Pressure [Mpa ]2. Results from long-term in-grid operation
Figure 1 shows the loading current and liquid nitrogen (LN2) characteristics of the HTS cable system during
the 400-days operation. Table 1 shows the operation results of the HTS cable. Twice of regular
maintenances were undertaken to evaluate the performance reliability of the HTS cable while the HTS
cable was separated from the grid.
Excluding
thisperiod,around1.4
80400-days of in-grid operation had been
T em perature of LN 2
realized without critical failures, thus
1.2
70
confirming the continuous and stable1
operation. The system also remained60
0.8
Current
stable against the suddenly fluctuating
current by network switching. The
0.6
50
operation kicked off with the
F low rate
0.4
temperature of LN2 at the cable inlet
40
0.2
controlled within a range of 69 ±1 K.
Press ure of LN2 in reservoir tankThen, the temperature was increased
030
10 /2 8
12/27
2/26
4/27
6 /2 7
8/26
10 /2 6
12/25
to 79 ±1 K to verify the stability atDayDayhigher LN2 temperature operation.
After in-grid operation, residual
Fig. 1 Loading current and LN2 characteristics of the cable system
performance tests were undertaken
and no degradation of critical current and electrical insulation characteristics was confirmed. It was
confirmed that keeping high vacuum of cryostat-pipe for a long time and improvement of refrigerator
performance such as capacity and efficient were necessary for practical use of HTS cable system.

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Tempe rature [K]Flo w ra te[li[iter/min]ter/min]

1. Project Outline
Tokyo Electric Power Company (TEPCO), Sumitomo Electric Industries and Mayekawa MFG wereinvolved in a project entitled, “High-temperature Superconducting (HTS) Cable Demonstration Project in thegrid,” commissioned by the New Energy and Industrial Technology Development Organization (NEDO), forthe period 2007-2013. A 66 kV and 240 m-long HTS cable system was constructed at Asahi substation of
TEPCO and was connected to a real grid for the first time in Japan. This project aims were to establish theoperational performance of the entire system technology including design, construction, operation,
maintenance. The following is the results acquired from the long-term in-grid operation.

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Table 1 Results of HTS cable’s operation
Item

Details

Operation period in grid10.29.2012 – 12.25. 2013
About 400 days: Excluding maintenance term

Maintenance period

6.10 – 6.21. 2013、7.22–7.31. 2013

Max current

1127 Arms (8.10. 2013）

Voltage in grid

63.9–67.1 kV

Unbalanced current rate

About 6.9 %Shielding current rate

About 89 %Network switchingMore than 50 times

Overloading

Not detected

ImpulseNot detected

Fault current

Once (Caused by ground fault in external part of
the HTS cable)

3. Future plans
To enhance the technologies of the above-mentioned issues and thereby realize a potential system forpractical use, the “Verification project for safety and reliability of next-generation transmission system,”commissioned by NEDO, commenced in July 2014. In this project, further safety test such as verification
against an accident and development of higher capacity/efficient refrigerator system are been conducting.
The former plan is evaluation of the behavior of the HTS cable including LN2 in case of the accident, suchas short circuit fault and ground fault. Another plan is to install the higher capacity/efficient refrigerator
system at the Asahi substation during 2014 and to operate this system from July 2015 with connecting the
240 m-long HTS cable for evaluation of its long-term performance.

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February, 2015

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