ELECTRIC WIRE & CABLE, ENERGY

In-Grid Demonstration of Long-length “3-in-One” HTS
Cable (Albany Project)
Hiroyasu YUMURA*, Yuichi ASHIBE, Masayoshi OHYA, Michihiko WATANABE,
Hiroshi TAKIGAWA, Takato MASUDA, Masayuki HIROSE, Ken YATSUKA, Hideki ITOH
and Ryosuke HATA

High-temperature superconducting (HTS) cable, characterized by its high current density and low transmission
loss, is a promising compact power cable with large transmission capacity, and has a variety of environmental
advantages such as energy saving, resource conservation and EMI-free. Due to these advantages, HTS cabledemonstration projects are being promoted around the world. Since the discovery of HTS materials, Sumitomo
Electric has been conducting the development of HTS BSCCO wires and three-cores-in-one-cryostat-type HTS
cables. Recently, Sumitomo Electric greatly improved the performance of BSCCO wires and developed a new wire
named DI-BSCCO. This improvement is accelerating the development of HTS applications, especially HTS cables.
The Albany Project is one of the demonstration projects for HTS cable in the United States funded by the
Department of Energy. In Phase I of this project that took place between July 2006 and May 2007, an HTS cablesystem using the “3-in-One” HTS cable manufactured by Sumitomo Electric operated successful over a practicallyused underground power grid in unattended conditions for the first time in the world. In Phase II that had started in
January 2008, after the world’s first replacement of HTS cable to 2G (YBCO) cable, the HTS cable system was reenergized and restarted operating in a live utility network. In the Albany Project, the HTS cable systemdemonstrated more than 12 months of reliable operation on a live grid during Phases I and II. This paper describes
the details of the in-grid demonstration results of the HTS cable system in the Albany Project.

1. Introduction
High-temperature superconducting (HTS) cables
achieve large-capacity, low-loss power transmission in acompact size and are expected to offer not only economical advantages but also environmental advantages likeenergy conservation, resource conservation, and electromagnetic interference (EMI)-free performance.(1) Dueto these advantages, HTS cable demonstration projects
and practical application studies are being promoted
around the world.
Sumitomo Electric Industries, Ltd. has been pursuing the development of HTS wires since 1986 when HTS
materials were first discovered. Since 1991, the Company
has been working to develop three cores-in-one cryostat
type (commercialized under the trade name “3-in-One ”)
HTS cables.(2), (3) It has promoted the development of
HTS cables and other HTS applications using its highperformance bismuth-based HTS wire (commercialized
under the trade name “DI-BSCCO”) that is manufactured
using a proprietarily developed sintering process named
the “CT-OP” process.(4), (5) Sumitomo Electric’s “3-in-One”
cable has become the first commercial HTS cable to successfully achieve in-grid operation through a practicallyused underground power grid in the Albany Project,
one of the HTS cable demonstration projects conductedby the United States Department of Energy (DOE).
In Phase I of this project, an HTS cable system consisting of two DI-BSCCO cables was energized on July 20,
2006 and began long-term in-grid operation.(6) From thattime, a long-term demonstration progressed satisfactorily without human intervention and was completed on

May 1, 2007. The HTS cable system achieved a total of nearly 6,800 hours of electricity transmission during Phase I.
In Phase II, a new HTS cable with YBCO coated conductors was manufactured and replaced one of the DIBSCCO HTS cables. The world’s first HTS cable replacement was completed successfully. The cable system wasre-energized and put back in service on January 8, 2008.
Then, the in-grid operation progressed satisfactorily andwas completed in the end of April 2008. In the Albany
Project, during Phases I and II, the HTS cable systemdemonstrated more than 12 months of reliable operationon the live grid. This paper summarizes the results of the
Albany Project’s long-term power transmission demonstration with an HTS cable system.

2. Albany Project overview
In the United States, the vulnerability of power gridhas been put as a major problem -- for example, it waspointed out as a factor in the massive blackout that
occurred in New York in August 2003 -- and strengthening the Country’s power grid is considered an urgent
issue. In the Energy Policy Act enacted in August 2005,
the upgrading of power transmission grid was identified
as an issue of vital national importance. One of the solutions for this problem is the “Grid 2030” initiative, toconstruct a strong nationwide power transmission grid
made up of HTS cables by 2030.(7)As part of this planning, HTS cable demonstration
projects have been conducted on the actual power grids,

SEI TECHNICAL REVIEW · NUMBER 68 · APRIL 2009 · 69

funded by the U.S. DOE. The Albany Project in which
Sumitomo Electric participated was one of these projects. The project was conducted on an actual power
grid extending approximately 3 kilometers between two
substations (Menands and Riverside) in the National
Grid electric utility system at Albany, the capital of New
York State. In the project, the two HTS cables were applied
to a 350-meter section in this power network.(8)2-1 System specifications/configuration
Table 1 and Fig. 1 show the specifications and a schematic view of the HTS cable system for the Albany Project. The rated voltage, current and transmission capability of this power network are 34.5 kV, 800 A, and 48 MVA,
respectively. The two Sumitomo Electric “3-in-One” HTS
cables, each 320 meters and 30 meters, were installed in
a 350-meter-long underground conduit having an innerdiameter of 6 inches (152 mm). The world’s first HTS
cable-to-cable joint was placed inside a vault, and bothends of the 350-meter-long cable created by jointing two
HTS cables were connected to overhead power transmission lines. The cables, a joint and the terminations were
designed in conformance with AEIC standard C55-94,
IEEE standard 404 and IEEE standard 48, respectively.

2-3 Project schedule
Table 2 shows the schedule for the project. In Phase
I, the HTS cable system consisting of DI-BSCCO cables
was installed and conducted long-term operation in thelive grid. In Phase II, a 30-meter-long section of the cablesystem was replaced by a new cable with YBCO coatedconductors, and the cable system went back in service. In
the project, more than 12 months of long-term operation was planned during Phases I and II.

Table 2. Albany Project Schedule
2002

2003
Design

2004

2005

Manufacture of BSCCO
wire and cable (350m)

2006
Site
construction

2007
Long-term
operation

Manufacture of YBCO
wire and cable (30m)

Replacementof30-msection

3. Albany Project - Phase I
Table 1. HTS Cable System Specifications

Items

Specifications

Cable structure

Three cores-in-one cryostat (“3-in-One”)

Voltage and current

34.5 kV, 800 Arms

Cable length

350 m (320 m + 30 m)

Accessories

Cable termination boxes (both ends)
Cable-to-cable joint (assembled in a vault)
Liquid nitrogen return pipe (350m)

Laying conditions

Underground conduit (inner diameter: 6 inches)

Maximum fault
current condition

23 kA, 38 cycles

OH lineTermination box

350m
High-way

3-1 “3-in-One” DI-BSCCO cable (6)The structure of the “3-in-One” HTS cable applied tothis project is shown in Photo 1. Three cable cores arehoused in a cable cryostat. This structure needs less cablelaying space and has lower heat invasion compared tousing three single-core HTS cables that require separate
cryostat for each core. Moreover, the “3-in-One” cable
design can also prevent the thermal contraction of coresthat is a problem experienced by HTS cables during thecable cooling process.
Table 3 shows the specifications of the DI-BSCCO
cable used in Phase I. A 320-meter cable and a 30-meter
cable were manufactured using the DI-BSCCO wires having high levels of critical current, mechanical properties,
uniformity over long lengths and anti-ballooning performance.(9) Polypropylene laminated paper (commercialized under the name “PPLP”) was used as the electricalinsulation material due to its good properties at low
temperatures such as high insulation strength and low

Joint
CRS

HTS cable
30m

Electrical Insulation(PPLP + Liquid Nitrogen)

Stainless Steel Double
Corrugated Cryostat

Fig. 1. Schematic View of HTS Cable System
Cu Stranded
Former

2-2 Project members
SuperPower, Inc. is the prime contractor for the project. National Grid, the Linde Group (formerly the BOCGroup) and Sumitomo Electric are participating as partners. As the host utility company, National Grid provided
the demonstration network. Linde provided the coolingand monitoring systems. Sumitomo Electric was in chargeof design, manufacture, construction and operation of
the HTS cable system.

35mm

135mm

Cu Shield
HTS Conductor(Double Layer)

HTS Shield(Single Layer)

Tension Member

Photo 1. Three Cores-in-One-Cryostat Type HTS Cable Structure

70 · In-Grid Demonstration of Long-length “3-in-One” HTS Cable (Albany Project)

Table 3. DI-BSCCO Cable Specifications

Items
FormerHTS conductor
Electrical insulation

Specifications
Stranded copper wires with insulation
Double layer of DI-BSCCO wires
PPLP (thickness: 4.5 mm)

HTS shield

Single layer of DI-BSCCO wires

Copper shield

Copper tapes

3-core stranding

Loosely-stranded 3-core structure

Thermal insulation
layer (cable cryostat)

Co-axial stainless steal corrugated pipes withmulti-layered thermal insulation materials

Protective outer
sheath covering

Polyethylene/stainless steel tapetension member

Cable outer diameter

135 mmdielectric loss. PPLP was immersed in liquid nitrogen toprovide composite insulation. The DI-BSCCO wires werewinded onto the electrical insulation layer of each core
to form a shielding layer. The shielding layers of the threecores were shorted at the termination at the both ends
in order to induce the shielding current that has almost
the same magnitude as the conductor current in the
opposite phase. As a result, perfect magnetic shielding
can be achieved in each cable core, and the magnetic
fields produced by other phases do not affect the HTS
wires in each core. Naturally, the outside of the cable isfree of EMI. In an AC power system, a fault current may
flow for a brief period of time in the event of a short circuit accident.To accommodate fault currents, stranded
copper wires were used as the conductor core material(former) and copper tapes were adopted to form a protective layer on the outside of the HTS shield. This design
can prevent temperature rise by passing the momentary
fault currents separately to the HTS wires and to thestranded copper wires or copper tapes.
The three cores are stranded loosely to create slack.
This “loosely-stranded 3-core structure” can absorb a thermal contraction of 0.3 % produced by temperature change
during the cool-down from room temperature to liquid nitrogen temperature (approximately -200 degrees Celsius).
To provide thermal insulation between the temperature outside the cable and the liquid nitrogen temperature inside the cable, the cable cryostat is made of a double-wall stainless-steel corrugated pipe with multi-layer
thermal insulation, and the space between the two pipe
walls is kept in a high vacuum state. This cable cryostat ischaracterized by high thermal insulation performance(low heat invasion performance). The result obtained fromthe evaluation of long-term vacuum performance of a 350meter-class cable cryostat showed that the vacuum level
was maintained at a level that heat invasion is small evenafter more than 100,000 hours since sealing. Therefore,
the cable cryostat was evacuated and sealed at a factory
while being maintained at an appropriate vacuum state.
The pulling tension on the 320-meter cable section
could be estimated to be about 2 tons at a maximum. As
this cable has a loosely-stranded 3-core structure, insteadof pulling the cores, a tension member made of stainlesssteel tapes was attached to the outside of the cable cryostat to divide the pulling tension. The outer diameter ofthe cable is 135 mm and it can be laid into the 6-inches(152 mm) underground conduit.
The cable structure as described above provides the
HTS cable with features such as low AC loss and EMI free.
And it also accommodates the required current and voltage
capacities, fault current condition and pulling tension.(10), (11)Table 4 shows the results of the various shipping tests
conducted after the completion of the DI-BSCCO cablemanufacture. As the results of these tests, it was confirmed that the cable has good properties as designed
and satisfies the required specifications. After successfully
passing the shipping tests, the cable was shipped to theUnited States.

Table 4. Results of DI-BSCCO Cable Shipping Tests (Sample Tests)

Test conditions andacceptance values

Tests

Test results

Critical current mea- Design value: 1.8 kA
surement(77K, defined by 1
(conductor / shield) µV/cm criterion)

Same as design value(1.8 kA/each phase)AC loss measurement

Design value: 0.7 W/m perphase (at 800 A, 60 Hz)

Same as design value(0.7 W/m per phase)

Cable bending test
(18D, D = cableouter diameter)

Critical current after
bending test
Dismantling inspection
after bending test

No Ic degradation
No defect in HTS
tapes and electricalinsulation

Withstand voltage
test (in accordance to AEIC
standard)

AC: 69 kV for 10 minutes
Imp.: ±200 kV(10 shots/each)
DC: 100 kV for 5 minutes

Good
Good
Good

3-2 HTS cable system installation at Phase I
The route profile for the HTS cable installation has a
90-degree bend with a radius of 12 meters and the maximum difference in elevation is approximately 5 meters.(6)Photo 2 shows the installation of the HTS cable. The
method applied to install the HTS cable was the same asthat commonly used for installing conventional cables.
The cable drum was placed on a drum roller and the cable
was pulled into the 6 inches (152 mm) underground conduit by a winch. The HTS cable was installed into the con-

Photo 2. HTS Cable Installation

SEI TECHNICAL REVIEW · NUMBER 68 · APRIL 2009 · 71

duit very smoothly and the maximum tension was approximately 2 tons, which was almost the same as the tension
value calculated in advance with a friction coefficient of
0.25.(6) Furthermore, after the cable installation was completed, it was confirmed that there was no abnormal elongation or external damage to the HTS cable, and there wasno degradation in the degree of vacuum level of the cablecryostats. This successful cable installation demonstrated
that the HTS cable could be installed using the same method
and same equipment as those for conventional cables.
After the HTS cables were installed, the cable-tocable joint was assembled in a vault (see Photo 3) andthe HTS terminations were assembled at both ends ofthe jointed cable (see Photo 4).(6) After being assembled,
the termination vessels were fixed to the ground.

fine adjustment of temperature, pressure and other operating conditions of the cooling system. This system enables
unattended operation of the HTS cable system.
3-3 Commissioning tests at Phase I (6)Table 5 describes the commissioning tests and theirresults for confirming the operational performance ofthe HTS cable system. After the completion of theinstallation of the HTS cable system, a withstand pressure test was conducted for the entire cable system
including the cooling system. The test was conducted inaccordance with the ASME standard for pressure vessels
in the United States. The test was conducted under acondition of 0.61 MPaG, which is 1.1 times the pressure
setting for the safety valves used in the system (0.55
MPaG). The test results confirmed that the HTS cablesystem was satisfactory with respect to this test condition.

Table 5. Results for Commissioning Tests of HTS Cable System (Phase I)

Tests

Photo 3. HTS Cable-to-cable Joint in Underground Vault

Test Results

System withstand pressure test (in accordance
to ASME standard)

0.61 MPaG: good

Initial cooling test

Maximum core tension: approximately 800 kg
Vacuum level in each section: good (noleakage)Core behavior inside the joint: within thescope of assumption

Critical current
measurement

2.3 kA (at 73 K), 2.8 kA (at 69 K)

Heat loss measurement
350-m cable section (including joint): 1.0 kW(under no-load condition) Entire cable system: 3.1 kW
Pressure drop measurement (flow rate:
50 L/min)350-m cable section (including joint):
0.075 MPa

DC withstand voltage
test (in accordance to 100 kV, 5 minutes, each phase : good
AEIC standard)

Photo 4. HTS Termination

A cooling system and a monitoring system were set up
by Linde concurrently with the installation of the HTS
cable system. The cooling system has a back-up mode to follow in the event of an equipment failure or a power outage,
thus ensuring reliability in actual operation.(12) The operating status of the HTS cable system is monitored 24 hours a
day via the network system from the Remote Operation
Center (ROC) at Linde. The operating status can also bemonitored in real time from anywhere around the world via
the Internet, so monitoring from Japan is also possible. In
addition to the monitoring of the HTS cable system’s operational status, the monitoring system also allows remote

In the initial cooling process, the maximum tension
produced at both terminations was a total of approximately 800 kgf for the three cores. This is much lower
than the tension produced when there is no provision foroffsetting heat contraction (approximately 5,000 kgf),
and the effectiveness of the “loosely stranded 3-core structure” is thereby reconfirmed. In addition, the vacuum
level in each section including the cables and the joint
was kept at a good level and the core behavior inside thejoint was also confirmed to be within the normal range.
Figure 2 shows the results of the critical current (Ic)
measurements conducted on the three phases of the
HTS conductor at the average cable temperatures of 73
K and 69 K. The Ic values defined by a 1 µV/cm criterion were 2.3 kA at 73 K and 2.8 kA at 69 K for each of all
three phases. These Ic values closely match the values estimated from the sample test results of 1.8 kA at 77 K and
the critical current vs temperature characteristic of the DIBSCCO wire as shown in Fig. 3. These results confirm that
there were neither defects nor deteriorations in the HTS

72 · In-Grid Demonstration of Long-length “3-in-One” HTS Cable (Albany Project)

2.5Core-1Core-2
Core-3

Electrical Field [µV/cm]

2

69K
average temp 73k

1.5
Ic criterion
crcriteriterionion (1µV/cm)(1 V/cm)

1
0.5
0
-0.5

0

500

1000

1500

2000

2500

3000

Current Load [A]Fig. 2. Critical Current (Ic) Measurement Results for HTS Conductors(in Phase I)

Critical Current [A, at 1µV/cm]

3500
3000

Ic-T characteristics
of DI-BSCCO wire

Ic in sample test
(1800 A at 77.3K)

2500
2000
1500

ed properly, demonstrated good performance and met
the required specifications. In addition, the cooling system allows operation in the back-up mode in the event ofa refrigerator failure, liquid nitrogen pump failure orelectric power failure, thereby ensuring stability of cabletemperature and pressure. In response to these favorable
results, the cable system was connected to the actual power
grid of National Grid on July 20, 2006. This was a historic
moment when power transmission on an actual power
grid by long HTS cables started. Photo 5 shows the HTS
cable system connected to the overhead power lines.
The operation of this cable system can be remotely
monitored and controlled. Two weeks after the cablesystem was first energized, the cable system shifted from
attended operation to unattended operation and continued to operate on the actual power grid while being
remotely monitored. The long-term in-grid operation of
the cable system progressed satisfactorily without humanintervention since then, and completed on May 1, 2007.
The results of the long-term in-grid operation at Phase I
are summarized in Table 6. The temperature and powertransmission values of the cable during the in-grid operation are shown in Fig. 4. The shutdown of the in-grid
operation had occurred just once, due to the inflow ofCommissioning test
(320m cable+30m cable)

1000
500
0
65

70

75

80

Temperature [K]Fig. 3. Comparison between Measured and Calculated Ic Values

conductors throughout the processes of manufacture, transport, installation and cooling of the long HTS cable.
The heat invasion into the cable system in no-loadcondition was measured. The heat loss in the 350-meter
HTS cable section (including the joint) was 1.0 kW andthat in the entire HTS cable system including the terminations, the return pipe and the pipes connecting to thecooling system was 3.1 kW. These heat loss values are consistent with design values. The pressure drop in the 350meter cable section under the condition of a liquid nitrogen flow rate of 50 L/minute was 0.075 MPa. This pressure drop value closely matches the design value of 0.07
MPa calculated using a duct friction coefficient of 0.08.
As the final test before energization, a DC withstandvoltage test was conducted in accordance with the AEIC
standard. This test is equivalent to the withstand voltage
test of a 34.5 kV-class cable after site installation. A DC
voltage of 100 kV was applied for 5 minutes to each phaseand good results were obtained. With the completion ofthis test, the cable system successfully passed all of the commissioning tests.
3-4 Cable energization and long-term in-grid operation at Phase I
The good results obtained in the commissioning
tests confirmed that the HTS cable system was construct-

Photo 5. HTS Cable System Connected to Overhead Power Lines

Table 6. Results of HTS Cable In-grid Demonstration (Phase I)

Items

Results

Notes

Peak load> 500 Arms–

Average load

~ 200 Arms–

Hours of continuous operation

2,700 hrs–

Total hours ofoperation

6,700 hrs–

Number of outages

1• Shut down by fault current(7 kA, 8 cycles)

Maintenance• A regularly-scheduled maintenance was performed
Refrigerator
while the cable is online.
maintenance • The back-up system was
deployed during maintenance.

SEI TECHNICAL REVIEW · NUMBER 68 · APRIL 2009 · 73

fault current from a remote and unrelated substation into
the HTS cable line via the grid. The waveform of the fault
current is shown in Fig. 5. The maximum current value
was 7 kA and it was cleared in 8 cycles when the first cableline protection system activated. This fault current inflow
did not cause any major change in cable temperature.
The backup power supply automatically activated during
a power outage to keep the cooling system running, andthe cable temperatures were thereby maintained. After
that, the soundness of the HTS cable system was confirmed, and then the in-grid demonstration was immediately resumed.
During the long-term in-grid operation, the maintenance of the cooling system components such as refrigerators was performed at a regularly scheduled time with cable being online by deploying the back-up mode operation.
Throughout the long-term in-grid demonstration,
the temperature and pressure in the cable system weremaintained at highly stable levels by the cooling system.
The cable system was never removed from service due toproblems related to the HTS cables. The long-term ingrid operation was completed successfully on May 1, 2007
and the HTS cable system had completed electricity trans-

71
Cable Outlet Temperature

Temperature [K]70

16

Cable Inlet Temperature

69

12

68

8

67

4
Shut Down
by Fault Current

Transmitted Electricity

66
7/20 8/17 9/14 10/12 11/9 12/7 1/4

Transmitted Electricity [MVA]20

mission over a total time of about 6,800 hours. On the
average, throughout the long-term in-grid demonstration,
the cable system provided 200 A to National Grid customers
with a peak load of more than 500 A.

4. Albany Project - Phase II
4-1 30-meter YBCO “3-in-One” cable(1) Cable structure
For Phase II of the Albany Project, a new 30-meter
HTS cable with YBCO coated conductor tapes was manufactured. The structure of the YBCO coated conductor
tape developed by SuperPower, Inc. is shown in Fig. 6.(13)It is composed of a YBCO HTS layer of approximately 1µm thickness, a multi-layered intermediate layer and thesilver and copper protective stabilizing layers on a Hastelloy substrate. The YBCO coated conductor tape has adimension of 4 mm width and 0.1 mm thickness. The total
amount of the YBCO coated conductor tapes used to
manufacture the 30-meter HTS cable is 9.7 km and theiraverage critical current is approximately 70 A.
The YBCO cable structure is shown in Photo 6. The
YBCO cable has a compact “3-in-One” structure similar
to the DI-BSCCO cable. The cable cores are composed of
the same copper former as the DI-BSCCO cores, a 3-layer
conductor, a PPLP dielectric layer of 4.5 mm thickness, a2-layer shield and a copper tape layer. The dielectric layer
thickness, copper tape layer cross-section area, and coreouter diameter of the YBCO cores are the same as thoseof the DI-BSCCO cores.
(2) Manufacture of YBCO cable and shipping tests
The 30-meter YBCO cable was manufactured under0
2/1

3/1 3/29 4/26

Date (2006-2007)

Fig. 4. Status of Long-term In-grid Operation (Phase I)

2µm Ag
1µm HTSYBCO HTS Layer~ 30nm LMO~ 30nm Homo-epi MgO Intermediate layer~ 10nm IBAD MgO

20µm Cu

Substrate
50µm Hastelloy substrate

SEL-311B
FID=SEL-311B-R105-V0-Z003002-D20020703 CID=3C2F

IA IB IC

IA

IB

IC

VA

5000

VB

Fig. 6. YBCO Coated Conductor Structure

VC

7kA

0

-5000

Electrical Insulation(PPLP + Liquid Nitrogen)8 cycle20
VA VB VC

20µm Cu

Stainless Steel Double-wall
Corrugated Pipe

Cu Stranded
Former

10
0
-10

35mm

-20
2.5

5.0

7.5

10.0

12.5

Cycles15.0
HTS Conductor(Triple layer)

Fig. 5. Fault Current Flow into HTS Cable System

74 · In-Grid Demonstration of Long-length “3-in-One” HTS Cable (Albany Project)HTS Shield(Double layer)

Cu Shield

Photo 6. “3-in-One” YBCO Cable Structure

135mm

the same conditions to those for the DI-BSCCO cable.
The results of the various shipping tests conducted after
the completion of cable manufacture are shown in Table 7.
Because the YBCO coated conductor tapes have lower Ic
than the DI-BSCCO ones, the YBCO cores have a 3-layer
conductor and a 2-layer shield, whereas the DI-BSCCO
cores have a 2-layer conductor and a 1-layer shield. Therefore, the YBCO cores were designed to have higher Ic thanthe DI-BSCCO cores. The results of these tests confirmedthat the YBCO cable demonstrated good properties as
designed and satisfied the required specifications. After
successfully passing the shipping tests, the cable wasshipped to the United States for installation.

formerly installed. After the replacement of the 30-meter
cable, the termination and the joint for connecting the
YBCO and DI-BSCCO cores were reassembled.
4-3 Commissioning tests at Phase II
The results of the commissioning tests conductedon the HTS cable system before re-energization are shownin Table 8.

Table 8. Results for Commissioning Tests of HTS Cable System (Phase II)

Tests

Test Results

System withstandpressure test
(in accordance to
ASME standard)

0.61 MPaG: good

Table 7. Results of YBCO Cable Shipping Tests (Sample Tests)

Tests

Test conditions andacceptance values

Test results

Initial cooling test

Critical current measurement(conductor / shield)

Design: 2.7 ~ 2.8 kA(conductor): 2.4 ~ 2.5 kA(shield)(77K, defined by
1µV/cm criterion)

Maximum core tension: approximately 1,000 kg
Vacuum level in each section: good (no leakage)
Core behavior inside the joint: within the scopeof assumption

Same as design value(Conductor: 2.7 kA,
2.8 kA, 2.7 kA)(Shield: 2.4 kA, 2.4
kA, 2.5 kA)

Critical current measurement

2.3 kA (at 73 K), 2.8 kA (at 69 K)

Heat loss measurement(under no-load condition)

350-m cable section (including joint): 1.0 kW
Entire cable system: 3.4 kW

AC loss measurement

Design (trial test):
0.4 W/m per phase(at 800 A, 60 Hz)

Same as design value(0.34 W/m perphase)

DC withstand voltage test
(in accordance to AEIC
standard)

100 kV, 5 minutes, each phase: good

Cable bending test
(18D, D = cableouter diameter)

Critical current afterNo Ic degradation
bending test
No defect in HTS
Dismantling inspection tapes and electricalafter bending test
insulation

Withstand voltage
test (in accordance
to AEIC standard)

AC: 69 kV for 10
minutes
Imp.: ±200 kV (10shots/each)
DC: 100 kV for 5
minutes

4-2 Replacement of 30-meter section with YBCO cable(1) Cable system warm-up
After the completion of the long-term in-grid demonstration in Phase I, the Megger test and the Ic measurement were conducted in order to check the soundnessof the HTS cable cores. The result of these tests showedthat the cables maintained good electrical insulation
properties and exhibited no change in Ic values. Afterthe soundness of the cables was confirmed, a warm-up of
the cable system was conducted in order to replace the
30-meter cable for Phase II. In the warm-up process, liquid nitrogen was collected in the bulk storage tank of thecooling system, and then the cable system was warmed
naturally. The entire cable system was warmed to ambient temperature in about three weeks. In the warm-up
process, the vacuum level in each section did not indicate any leakage.
(2) HTS cable replacement
After the warm-up of the cable system, the joint andone of the two terminations were dismantled and the 30meter DI-BSCCO cable was pulled out from the underground conduit. The YBCO cable was placed in the 30meter section where the 30-meter DI-BSCCO cable was(1) System withstand pressure test
After the replacement of a 30-meter cable section andthe reassembling of the cable system were completed, awithstand pressure test was conducted under a conditionof 0.61 MPaG as was in Phase I. The test results proved the
HTS cable system satisfactory under this test condition.
(2) Initial cooling test
The initial cooling of the HTS cable system was conducted by controlling the temperature in the lengthwise
direction of the cable in the same manner as was in Phase
I. Figure 7 shows the temperature profiles obtained by an
optical fiber in the cable during the initial cooling process.

50

South
Termination

North
Termination

0H

0Temperature [C˚]

Good
Good
Good

6H
10H

-50

18H

1D

1.5D
3D

-100
9D

-150

10.7D

10.8D 10.9D 11.5D

10.5D

-200
0

50

100

150

200

250

300

350

Position in Cable [m]Fig. 7. Temperature Profile along Cable Length in Initial Cooling Process(Phase II)

SEI TECHNICAL REVIEW · NUMBER 68 · APRIL 2009 · 75

active vacuum treatment. This result shows that the cablecryostats have kept a good performance without maintenance for a long time approximately three years including
thermal cycles. The heat loss of the entire HTS cable system
including the terminations, the return pipe and the pipes
connecting to the cooling system was 3.4 kW, which wasnearly identical to the value obtained in Phase I.
(5) DC withstand voltage test
As the final test before cable re-energization, a DC
withstand voltage test was conducted in conformity with
the AEIC standard. A DC voltage of 100 kV was applied for
5 minutes for each phase, and good results were obtained.
With the completion of this test, the cable system again
successfully passed all of the commissioning tests.
4-4 Re-energization and long term in-grid operation
at Phase II
The good results obtained in the commissioning tests
confirmed that the replacement of the 30-meter DI-BSCCO
cable with a 30-meter YBCO cable was completed successfully and demonstrated that the cable system has met therequired specifications. In response to these favorable
results, the cable system was re-connected to the live powersystem of National Grid and was back in service on January
8, 2008. The operation of this cable system was able to bemonitored and controlled remotely. From that time, a longterm in-grid demonstration progressed satisfactorily without
human intervention and was completed successfully at theend of April 2008 as was original scheduled. The cable temperature and transmitted electricity during the in-grid operation at Phase II are shown in Fig. 9.

7120Energized
on Jan 8,08

Temperature [K]70Electrical Field [µV/cm]

2.5
Core-1Core-2
Core-32

average temp
73K
69K

1.5

16

69 Cable Inlet Temperature

12

68

8

67

4
Transmitted Electricity

Ic criterion
crcriteriterionion (1µV/cm)( V/cm)1

Cable Outlet Temperature

Transmitted Electricity [MVA]

The cable was cooled gradually for the entire length using
nitrogen gas whose temperature was -100 degrees Celsius,
and then the temperature of the nitrogen gas being fed
into the cable was gradually lowered. When the temperature at the inlet of the cable was -150 degrees Celsius andthe temperature gradient for the entire length of thecable had become sufficiently small, liquid nitrogen wasthen injected into the cable. The entire length of the cable
was cooled to the liquid nitrogen temperature in about
12 days that was almost same period of time as that inPhase I. In the initial cooling process, the maximum tension produced at both terminations was a total of approximately 1,000 kgf for three cores. This is much lower
than the tension produced when there is no provision foroff-setting heat contraction (approximately 5,000 kgf), thus
it was confirmed that the HTS cable maintains the “loosely stranded 3-core structure” even after the cable replacement. In addition, the vacuum level in each section
showed no deterioration and the core behavior inside thejoint was also confirmed to be within the normal range.
(3) Critical current measurement
After the initial cooling process was completed, criticalcurrent (Ic) measurement was conducted on each conductor made of the YBCO core and the DI-BSCCO core at the
average cable temperatures of 73K and 69K, which are thesame temperature condition as that in Phase I. Because theIc value of the YBCO core is higher than that of the DIBSCCO core, measured Ic value should be determined by
the Ic value of the 320-meter DI-BSCCO cable. The measured Ic value was 2.3 kA at 73K and 2.8 kA at 69K for all
three phases as shown in Fig. 8. These Ic values are thesame as the values measured during Phase I. Therefore, it
was confirmed that there was no severe damage on the
YBCO cable cores after installation and there was no damage on the DI-BSCCO cores after thermal cycles.

066
1/7 1/14 1/21 1/28 2/4 2/11 2/18 2/25 3/3 3/10 3/17 3/24 3/31

0.5

Date (2008)

0Fig. 9. Long-term In-grid Operation Status (Phase II)
-0.5
0

500

1000

1500

2000

2500

3000

Loading Current [A]

5. Project outline

Fig. 8. Results of Critical Current (Ic) Measurement for HTS conductors (Phase II)(4) Heat loss measurement
Heat invasion into the cable system in a no-load condition was measured. The heat loss in the entire 350-meter
HTS cable section was 1.0 kW, which was identical to thevalue obtained in Phase I. After the cable was manufactured at a factory, the cable cryostats did not require any

The verification items and demonstration results of
the Albany Project are summarized in Table 9.
① The long-length “3-in-One” HTS cables designed
to meet the required specifications were manufactured successfully.
② The cables and cable accessories such as joint andterminations were designed to meet the related U.S.
standards.

76 · In-Grid Demonstration of Long-length “3-in-One” HTS Cable (Albany Project)

Table 9. Albany Project Summary

Verification Items

Demonstration Results

Cable design

Agreement with requirements • The HTS cable design was verified to satisfy the specifications required infor use in actual live grids
terms of current capacity, voltage, installation condition, fault current, etc.

Cable manufacturing

Long-length cable manufacturing• Two “3-in-One” HTS cables having a total length of 350 meters that satisfy
local standards were manufactured successfully.

Accessories design andmanufacturing

Agreement with local standards• The cables and accessories were designed to meet e related U.S. standards.

Shipping and transportation

Long-distance transportation• A long-distance transportation by sea and by land from Japan to the U.S
was demonstrated.

Installation into actual underground conduit• It was demonstrated that the HTS cable could be installed into the underground conduit with a pulling tension of 2 tons, using the same method
and equipment as those for conventional cables.

Cable-to-cable joint• The world’s first HTS cable-to-cable joint was assembled in the actual
underground vault.

HTS cable system construction• The construction of the HTS cable system was completed on schedule
without any problem or damage in the HTS cables.

Cable replacement• The world’s first replacement of the HTS cable was completed successfully.

Commissioning tests• The HTS cable system passed various tests and was confirmed to meetexacting utility standards. It had garnered approval for connection to thelive power grid.

In-grid operation• The HTS cable system was able to operate for more than 12 months without human invention.

Reliability• There was no downtime or power outage caused by the trouble of HTS
cables and the cooling system.
• On the event of fault current, there was neither damage nor significant
temperature change in the HTS cables.
• There were no change in the critical current values of the HTS conductors during the long-term operation including several thermal-cycles.
• It was demonstrated that the cable cryostats had a long life without any
active maintenance.

Maintenance• A regularly scheduled maintenance for the cooling system components
was performed while the cables were in an online state.

In-grid HTS cabledemonstration③ It was confirmed that there was no damage on thecables and accessories as a result of the long-distance transportation by sea and land from Japan
to Albany, NY.
④ The demonstration proved that the HTS cables
could be installed into the actual underground
conduit using the same method and same equipment as those used for conventional cables.
⑤ The world’s first HTS cable-to-cable joint which isessential for constructing a long-length cable network was demonstrated in an underground vault.
⑥ The construction of the HTS cable system in thelong-length actual grid was successfully completed on schedule without any problem or damage
in the HTS cables.
⑦ The replacement of HTS cable, which would benecessary in the future, was demonstrated in the
project for the first time in the world.
⑧ The HTS cable system has passed all of the various
commissioning tests and was confirmed to meetthe exacting utility standards. The HTS cable system has got certified to be connected with the live
grid from the utility company, National Grid.
⑨ The HTS cable system successfully operated unattended in the actual grid for more than 12 months,.
⑩ During the long-term in-grid operation, there wasno operational problem with the HTS cable system, and neither the cable nor the cooling systemcaused downtime or power outage. The HTS cablesystem demonstrated reliable operation on the live
power grid network.
⑪ The HTS cable system was demonstrated underreal-world utility conditions including events ofsignificant fault currents. The cable and the cooling system showed no damage, and the cable wasmaintained at a stable temperature level even in
the event of fault current.

2500
Critical Current [A, at 73K]

HTS cable systemconstruction in actual grid

2000
1500
1000
500

Core-1Core-2
Core-30
Sample Test PhaseⅠ

PhaseⅠ

PhaseⅡ

PhaseⅡ(after cool-down)(after long-term
operation)(after cool-down)(after long-term
operation)

Fig. 10. Critical Current Variation (Phases I and II)

SEI TECHNICAL REVIEW · NUMBER 68 · APRIL 2009 · 77

⑫ It was confirmed that the critical current value did
not change throughout Phases I and II including
thermal cycles, as shown in Fig. 10.
⑬ The temperature difference between the outlet
and inlet of the cable, indicated by the heat lossof the cable cryostat, was very small and stablethroughout Phases I and II including thermal
cycles, as shown in Figs. 11 and 12. It demonstrated that the cable cryostats did not undergo
any major change in heat loss and had long lives
without any active maintenance.
⑭ It was demonstrated that regularly-scheduled maintenance for the refrigerator and other componentsof the cooling system could be performed while thecables are in an online state by deploying the backup mode operation.
“Of importance to National Grid is that this project
has demonstrated the reliability of the technology,” said
William Flaherty, Energy Solutions Regional Director for
National Grid. “We encountered no difficulties in integrating the project into our grid and the entire installation was
totally transparent to our customers. The system has stoodup to very exacting utility standards and we look forward tofurther developments in HTS technology.”

20

1.2
1

16

0.8
12
0.6
8
0.4
4

0.2
Transmitted Electricity

07/20 8/17 9/14 10/12 11/9 12/7 1/4

2/1

Transmitted Electricity [MVA]

TemperatureDeference [K]Temperature Deference between Cable Outlet and Inlet0

3/1 3/29 4/26

Date (2006-2007)“Projects such as this one are demonstrating thatHTS technologies have the potential to play a critical rolein modernizing our electric infrastructure and ensuring
the stable and affordable delivery of electricity to ourhomes and businesses,” said Patricia Hoffman, Deputy
Assistant Secretary for Electricity Delivery and Energy
Reliability at DOE. “The development and deployment ofsuperconductivity and other advanced energy technologies are critical to the Bush Administration’s ongoing
efforts to increase efficiency and reliability in our nation’senergy delivery infrastructure and to enhance our overallnational energy security.”
The HTS cable system has met all the objectives ofthe program. The world’s first integration of HTS cable
into a live power grid and long-term in-gird operation
demonstrated the reliabilities of the HTS cable system.

6. Conclusions
In the Albany Project, the HTS cable system demonstrated reliable operation on the live grid for more than
12 months, providing power to about 25,000 homes andbusinesses. In the United States, followed by this project, the in-grid demonstrations of the HTS cable systems have began in the Ohio Project (started at September2006) and in the LIPA Project (started at April 2008) .
Moreover, an in-grid HTS cable demonstration project
has started in Japan from FY2007.(15) Through longstanding and unr-emitting development efforts, HTS technology including HTS cables is steadily going from dream
to reality. For full-scale practical application of HTS cables,
further performance enhancement and cost reduction are
required to HTS wires. Also, further capacity increase
and loss property decrease are required to HTS cables,
and cable systems need to be constructed in a shorter
period. Sumitomo Electric is making further efforts to put
HTS cables to commercial use with confidence that HTS
technology is an absolute necessity for protection of energy, resource and environment in the 21st Century.

Fig. 11. Temperature Difference and Transmitted Electricity Variations(Phase I)(1)(2)
Temperature Deference [K]Temperature Deference between Outlet and Inlet of Cable

1

16

0.8

12

0.6
8
0.4
4

0.2
Transmitted Electricity

0
1/7

1/21

2/4

2/18

3/3

3/17

Transmitted Electricity [MVA]

20

1.2

0
3/31

(3)

(4)
(5)

(6)

Date (2008)

Fig. 12. Temperature Difference and Transmitted Electricity Variations(Phase II)(7)

References
M. Hirose, et.al., “Study on Commercialization of High-Temperature
Superconductor”, SEI Technical Review, No.62 (June 2006)
T. Masuda, et.al., “High-Temperature Superconducting Cable Technology and Development Trends”, SEI Technical Review, No.59(January 2005)
T. Masuda, et.al., “Verification Test Results of 66kV 3-core High Tc
Superconducting Cable (1), (2)”, 2003 IEEJ National Convention,
7-094, 7-095
T. Kato, et.al., “Development of Drastically Innovative BSCCO (DIBSCCO) Wire”, SEI Technical Review, No.62 (June 2006)
Y. Yamada, et.al., “Examples and Future Prospects of High-Temperature Superconductor Products”, SEI Technical Review, No. 65(October 2007)
H. Yumura, et.al., “World’s First In-grid Demonstration of Longlength “3-in-One” HTS Cable (Albany Project)”, SEI Technical
Review, No.64 (April 2007)“Grid 2030 A National Vision for Electricity’s Second 100 Years”,
DOE (2003)

78 · In-Grid Demonstration of Long-length “3-in-One” HTS Cable (Albany Project)

(8)C. Weber, et.al., “Overview of the Underground 34.5kV HTS Power
Cable Program in Albany, NY”, IEEE Trans. on Applied Supercond.,
Vol.15, No.2, pp1793-1797 (2005)(9) N. Ayai, et.al., “Achievement of High-Temperature Superconducting
Wire with Critical Current Exceeding 200A”, SEI Technical Review,
No.63 (December 2006)(10) Y. Ashibe, et.al., Development of HTS Cable for Albany Project in
USA (2)”, 2005 IEEJ National Convention(11) T. Masuda, et.al., “Design and Experimental Results for Albany
HTS Cable”, IEEE Trans. on Applied Supercond., Vol.15, No.2,
pp1806-1809 (2005)(12) R. Lee, et.al., “Performance Testing of a Cryogenic Refrigeration
System for HTS cables”, Advances in Cryogenic Engineering Trans. of
the Cryogenic Engineering Conference, Vol.51, pp773-781 (2006)(13) V. Selvamanickam, et.al., “Progress in Scale-up of 2G Wire at SuperPower”, 2007 U. S. DOE Peer Review, Superconductivity for Electric
Systems, August 7-9, 2007, Arlington, VA(14) M. Ohya, et.al., “Design and Evaluation of YBCO Cable for the Albany
Cable Project”, Advance in Cryogenic Engineering Trans. of the
Cryogenic Conference, Vol.53B, pp1059-1066 (2008)(15) H. Yumura, et.al., “A New HTS Cable Project in Japan”, Submitted
to Applied Superconductivity Conference 2008

H. ITOH• Senior Staff, Power Cable Accessories Division, JPower Systems Corp.

R. HATA• Dr. Eng., Chief Engineer, Electric Wire & Cable,
Energy Business Unit

Contributors (The lead author is indicated by an asterisk (*).)

H. YUMURA*• Manager, Superconductivity & Energy
Technology Department
He is engaged in the development of
HTS cables and their systems.

Y. ASHIBE• Assistant Manager, Superconductivity & Energy
Technology Department

M. OHYA• Dr. Eng., Superconductivity & Energy Technology
Department

M. WATANABE• Assistant General Manager, Superconductivity &Energy Technology Department

H. TAKIGAWA• Assistant Manager, Superconductivity & Energy
Technology Department

T. MASUDA• Senior Assistant General Manager, Superconductivity& Energy Technology Department

M. HIROSE• Senior Assistant General Manager, Superconductivity& Energy Technology Department

K. YATSUKA• Senior Assistant General Manager, Superconductivity& Energy Technology Department

SEI TECHNICAL REVIEW · NUMBER 68 · APRIL 2009 · 79