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and propels the
train. Nexans provided 1,000 km of specially
adapted long stator
winding (LSW) cable to create this field,
and has now developed a new version of AERO-Z[R]
conductor for the next generation of maglev
projects.
 Flying at zero
altitude
Anyone who has
taken the Shanghai Transrapid has only nice
things to say about it. When leaving the
platform first there is the nearly
imperceptible lift, as it rises 10
millimetres over the height of the guideway.
Then follows a smooth but rapid
acceleration, like a jetliner taking off but
without the bumps and the scream of the
engines. Soon you are travelling at 430 km/h
(significantly beyond the 250-300 km/h of a
conventional high-speed train), and what you
notice next is the silence, a mere 60
decibels at 300 km/h which is just slightly
higher than a home interior (50 dBA).
Before you even know it, the Transrapid has
covered the 30 km between the city centre
station and the Pudong International Airport
in a mere eight minutes. When the direction
of force in the travelling magnetic field is
reversed, the motor becomes a generator
which gently brakes the vehicle smoothly
without friction or contact.
Nexans, which manufactures a wide range of
power and energy cables for both rolling
stock and railway infrastructure, supplied
the cables that made this extraordinary trip
possible. Key to the project was the Long
Stator, composed of the long stator winding
(LSW) cable together with the stator pack
which creates the magnetic levitation
(maglev) needed to lift, propel and guide
the Transrapid vehicle over the elevated
guideway.
The history of
an idea
Maglev
technology does not date from yesterday. The
first application for a patent concerning a
magnetic levitation train with wheel-less
vehicles was filed by German engineer,
Hermann Kemper, back in 1934. The German
Ministry of Transport commissioned a study
in 1969 to explore the possibilities for the
development and introduction of a high-speed
train. By 1977, a decision was made in favour of the long stator levitation
technology used today. 1979 was a landmark
date, when the first high-speed train was
authorized for passenger transportation at
the Hamburg International Transport
Exhibition.
Then, the construction of the Transrapid
test facility in Emsland (Germany) in the
eighties made it possible to test and
evaluate equipment in continuous operation.
Already, at that early stage, Nexans had an
important role in equipping the 31.5 km
trial track with the required cables and
components. By 1991, the Transrapid had
broken nearly all speed records.
However, it was only January 2001 that the
first commercial order was awarded by the
Chinese Government to Transrapid
International, ThyssenKrupp Transrapid and
Siemens Transportation Systems acting as
prime contractor for the vehicles, guideway
equipment, operation control technology and
power supply. The project was executed with
incredible speed, the initial trip taking
place only two years later.
According to Nexans' project manager Dirk
Steinbrink, the Shanghai maglev project
showed considerable foresight on the part of
the Chinese:
"They were very courageous in making this
decision and showed sound business sense.
Whereas the West thought only in terms of
expense, and the problem of interfacing with
other transport media, the Chinese were
excited by the long-term implications. By
holding us to tight deadlines, they forced
us to speed up innovation and
implementation, making it a very feasible
undertaking. The Europeans came up with the
idea; but the Chinese accomplished it."
Maglev
technology
Cables are a
vital part of the Transrapid system. In a
conventional electric motor, the rotor spins
within the magnetic field created by the
encompassing stator. However, in maglev
technology, the stator is opened up and
stretched along the ground. This "long"
stator consists of three winding cables
(phases) which are installed in stator packs
on both sides under the guideway in a
meandering and crimped configuration. The
long stator thus functions as the active
part of the motor which elevates and pulls
the passive part--the train
("rotor")--forward.
Aside from super high speeds, this
technology offers a number of important
benefits. Since the magnetic field can be
easily controlled at a distance, there is no
need for a driver. Also, with minimal
friction (air resistance), there is no wear
and tear on the system, and consequently
lower maintenance. The Transrapid is also
supremely smooth and quiet, with no need for
a conventional suspension or braking system.
By changing the frequency, the speed is
infinitely variable, and can be reversed for
braking and travelling in both directions.
Finally, since the train is far lighter and
as only one kilometre of the guideway is
energized at a time, energy consumption is
significantly lower.
In short, no other public transportation
system can carry so many people as fast, as
safely and as ecologically. The Shanghai Transrapid is expected to carry over 10
million passengers a year.
The long stator
winding (LSW) cable challenge
Nexans faced a
number of challenges in creating a cable
which could energize propulsion via a pulsed
medium-voltage power supply of 20 kV. There
were a number of special properties involved
which are not normally required of a power
cable. Since the magnetic field is created
by meandering the three separate phases on
both sides of the guideway in stator packs,
it had to be bent to a tight
U-configuration, and hold its shape to be
self-supporting. Even after bending, it had
to remain uniformly round. It also had to be
easy-to-install by automated laying robots
which would bend, crimp and press the three
cables into the stator pack grooves.
Also, due to the Chinese concern with
launching the project as quickly as
possible, manufacturing and delivery speed
was an important factor. There was also the
specific demand of producing extremely long
individual lengths of up to 3 kilometres,
and winding it onto special drums.
The Nexans
solution
The project's
managing director, Dietmar Steinbach,
explains how Nexans was able to face the
triple challenge of innovation,
manufacturing and delivery.
"Since we had been involved in Transrapid
test runs for years in Germany, we had
already accumulated the experience needed to
develop a long stator winding cable which
could deliver a homogenous electrical field,
and meet all of the special requirements.
However, there is a big difference between
producing 1,000 metres of cable for a test,
and 1,000 kilometres for an actual
installation, especially within a short
timeframe and meeting the high customer
requirements on each of the 1,000,000 metres.
In the end, we delivered 340 six-tonne drums
to specification within nine months. This
required a mobilization of the all relevant
personnel into round-the-clock shifts, seven
days a week."
The custom LSW design was a rubber-sheathed
300[mm.sup.2] aluminium cable with
mechanical properties that even seem to
supersede its high electrical functionality.
The conductor has superior bending
properties and can maintain the shape given
by the bending and crimping unit of the
laying robot without degradation of the
electrical performance.
Since easy installation was an issue, Nexans
worked closely with a specialized company,
Ferrostaal, Germany, to develop a new laying
process using six locomotive-sized robots.
Then it trained German trainers who
eventually transferred skills and supervised
an all-Chinese installation team. The
cable's outer coating was also very
important for easy installation. First, it
had to glide easily through the robot and
into the stator pack groove. Nexans went to
an automotive manufacturer and purchased
equipment that made it possible to provide
all cables with a stable and uniform
Teflon-based coating with special gliding
properties.
In addition to being highly resistant to
plain air, and aggressive environmental and
chemical threats, the cable's outer sheath
is flame-retardant to assure optimal safety
for passengers, personnel and equipment. The
cable is also ozone and oil resistant.
Nexans provided other critical cables and
components, as well, such as several parts
of the grounding system of the long stator
and the connecting cables to link the motor
winding and power supply. Nexans also
supplied the critical connections between
the long stator winding cables and the
connecting cables. About 2,000 cold shrink
joints were installed along the line, and
about 800 terminations were used to connect
these cables inside the switching stations.
The Shanghai Transrapid has eight
electro-mechanical switches to enable the
train to change guideways or turnout to the
maintenance centre. All motor control and
databus cables, as well as the connectors
for drive and accurate control of the
actuators were produced by Nexans.
AERO-Z[R], the next generation LSW
Even as the Shanghai Transrapid project was
nearing completion, Nexans was already
working on a new version of LSW cables,
based on what it had learned in China, and
the potential of one of its time-proven
products.
Nexans' AERO-Z[R] conductors are originally
designed as highly-sophisticated bare
overhead power lines for high-voltage
transmission up to 380 kV. Their uniqueness
lies in the interlocking Z-shaped layers
which form a circular belt around the core
giving them superior voltage capacity with
the same cross-section. These conductors
offer features like high tensile strength
needed for longer spans, reduced corrosion
and various technical advantages.
Although some features of AERO-Z[R] may seem
irrelevant to the specialized world of
maglev applications, others are highly
relevant, among them the ability to achieve
higher voltage capacity with a similar
cross-section, and its significant stability
against dynamic mechanical stress.
Not only will the new hybrid cable
significantly reduce bending force for more
secure long stator fits, it is also easier
to shape into the required U-form, and holds
its shape better. It also delivers
significantly more power than the standard
version, which also means that its diametre
could be slightly reduced if required. The
first practical implementation is already
installed on the TVE in Lathen, Germany.
For all of these reasons, AERO-Z[R] is very
likely to be a leading contender for the
next generation of Transrapid LSW
applications.
Future Transrapid projects around the world, there are a host of potential and
exciting Maglev projects on the transport
horizon.
Among the 5-10 serious maglev projects under
discussion are the new line from Munich
airport to the city centre, and a regional
maglev for either Pittsburgh or Baltimore in
the US.
Plans are already underway to extend the
Shanghai line by 2010 or 2012, and another
new line is planned between Shanghai and Hangzhou, a distance of about 180 km, and a
further line to Nanjing, of roughly the same
length. The ultimate dream is a
Shanghai-Beijing connection which could mean
making a breathtaking 1,000 kilometre
journey in a mere two hours, the time it
sometimes takes to get to the airport in a
major city.
 Wherever and whenever such projects
materialize, long stator winding cables will
provide the magnetic driving force -maglev-.
Meanwhile, Nexans is still the only cable
company in the world to have produced and
installed a complete set of long stator
winding cables for a commercially operating
maglev system.
For further reference: ZEVrail, Glasers
Annalen, Sonderheft Transrapid,
Nexans cables are the "motor" for Shanghai's
Transrapid
International Railway Journal Simmons-Boardman
Publishing Corporation and Gale Group
Shanghai expands
for Expo
International
Railway Journal
THE World Expo in Shanghai in 2010 is the
catalyst for a massive expansion of
transport infrastructure in China's second
city.
Shanghai plans to serve both its airports by
metro under a wider plan that will add 510km
of track by the time the Expo takes place.
The city's Urban Planning Administrative
Bureau said in May that it will provide 12
new lines and 10 new interchange hubs with
the aim of cutting travel times to the city
centre to a maximum of 45 minutes. At the
moment Shanghai has four metro lines with a
total length of 82km, with another 22km
under construction.
The line to serve the airports at Hongqiao
and Pudong will be extensions at both ends
of Line 2.
COPYRIGHT Simmons-Boardman Publishing
Corporation and Gale Group |