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Alstom confirms research findings, done with RTE, in high-voltage DC circuit-breaker technology

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Alstom has successfully completed tests on its high-voltage DC circuit-breaker prototype. The latest series of tests consisted of reproducing real operational constraints of a high-voltage DC transmission grid. These tests mark the final stages of work headed by RTE for the operation and protection of DC grids in Europes TWENTIES research project, co-funded by the European Commissions FP7 programme. This work contributes to the development and implementation of new technology, facilitating the integration of renewable energy into Europes electric power system.

The new series of tests complete the previous positive results observed with the prototype in the Villeurbanne testing facility last March. The key progress in these latest tests is the validation of equipment behaviour under actual operating conditions, using voltage that was high enough to carry power over long distances. In particular, they demonstrated the structures resistance to standard lightning impulse voltage[1], to transient currents exceeding 10 kilo-amps, and to heating caused by permanent current[2] and by overload current[3]. The current that was interrupted during the tests had reached over 5,200 amps, with switching voltage peaking at more than 160 kilovolts. The interruption and total extinction of current across the grid were achieved in less than 5.5 milliseconds, thereby succeeding in the most challenging part of the circuit-breakers mission.

Through these new tests, Alstom Grid asserts its leadership in the innovation of a key technology for the development of high-voltage power grids. The circuit-breaker acts as a lynchpin in power grid protection in the event of a short-circuit. While they are well mastered when used in AC grids, they demand the development of radically new technology in the case of DC grids. Operators are making increasing use of direct current to guarantee that power is carried efficiently over long distances, as well as to stabilise the grid with a growing supply of power from renewable and intermittent sources.

Alstom Grid R&D Vice President Stephan Lelaidier states, With close to 4% of its annual turnover invested in R&D every year, and with 1,200 expert engineers and 34 technology and research facilities worldwide, Alstom Grid possesses the required means and skills to stand at the cutting edge of technology in the power transmission sector. The prototype currently being developed is a major technological device in the deployment of DC grid networks. It will help to increase the share of renewable energy on the grid.

RTE R&D Director Olivier Grabette adds, This outcome from exemplary cooperation paves the way to a new period of development for power grids, towards the integration of a growing share of renewable energy. As a fundamental building block for the emergence of what is sometimes referred to as Supergrids, DC circuit-breakers are placing Europe in pole position for this new technology race.

All tests were witnessed by an RTE representative and by representatives from an independent, RTE-mandated test laboratory. The latest test, validating the power switching performance, was conducted on 29 November 2013, in the presence of representatives from RTE, Red Electrica España, TenneT and European Commission Project Officer Matthieu Craye.

About RTE

RTE (for Réseau de Transport dElectricité or Power Distribution Network) is a service company. Our fundamental mission is to provide all of our customers with access to a power supply that is economical, safe and clean. RTE connects its customers via an appropriate infrastructure, supplying them with all of the tools and services they will require to take advantage of it in order to meet their needs, and does so with an eye towards business efficiency, environmental friendliness and the safe procurement of energy. To that end, RTE is operating, maintaining and developing the high- and very-high-voltage grid. It ensures the power system functions correctly and safely. RTE transports electricity from power suppliers (French and European) to consumers, whether they are power distributors or industrialists who are directly connected to the transport grid.

With its 100,000 km in lines ranging from 63,000 to 400,000 volts and its 46 cross-border lines, the grid managed by RTE is Europes largest. In 2012, RTE boasted a 4,529m turnover, and employs 8,400 people.

About Alstom

Alstom is a global leader in the world of power generation, power transmission and rail infrastructure and sets the benchmark for innovative and environmentally friendly technologies. Alstom builds the fastest train and the highest capacity automated metro in the world, provides turnkey integrated power plant solutions and associated services for a wide variety of energy sources, including hydro, nuclear, gas, coal and wind, and it offers a wide range of solutions for power transmission, with a focus on smart grids. The Group employs 92,000 people in around 100 countries. It had sales of 20 billion and booked close to 22 billion in orders in 2011/12.

Alstom Grid has over 130 years of expertise in electrical grids. Whether for utilities or electro-intensive industries or facilitating the trading of energy, Alstom Grid brings power to its customers projects. Alstom Grid ranks among the top 3 in the electrical transmission sector with an annual sales turnover of more than 4 billion. It has 20,000 employees and over 90 manufacturing and engineering sites worldwide. At the heart of the development of the Smart Grid, Alstom Grid offers products, services and integrated energy management solutions across the full energy value chainfrom power generation, through transmission and distribution grids and to the large end user.


As part of its support for the gradual integration of renewable energy (especially wind energy), the European Union launched the TWENTIES project in April 2010, the objective of which is to substantially increase the development and implementation of new technology that will facilitate the integration of wind-produced energy into the European power system.

Through the inception of six wide scale R&D projects, the TWENTIES project intends to overcome obstacles to the integration of wind energy (both land-based and offshore) into the European system by 2020. This R&D aims at demonstrating the benefits of new technology, often paired with innovating management methods.

TWENTIES is the most extensive R&D project ever funded by the European Commissions Directorate-General for Energy. The project is coordinated by REE (manager of Spains power distribution grid,) who works with 25 companies and institutions from 10 Member States and one Associate Country.

Press Contacts:


Thierry Lartigau Tel +33 1 41 02 16 78 / 06 23 67 83 93


Virginie Hourdin, Claire Biau - Tél.: +33 1 41 49 21 36 / 39 95 /

Nathalie Bourotte (Alstom Grid): Tél.: +33 1 49 01 62 17

[1] Lightning impulse withstand according to IEC 62271-1: the device can withstand lighting impulse voltage with no operational degradation.

[2] Heating caused by permanent current: the device carries normal grid current without exceeding the maximum temperature rise accepted by the standards.

[3] Overload current: without any performance degradation the device can carry overload current for a limited duration if it is necessary for the grid's operation under stable conditions.