Hanover/Erlangen, Germany, April 20, 2009 -- With the continuous increases in the size of wind farms and in the capacity of wind turbines the operating voltage of wind farm power systems is also being increased to keep power transmission losses as low as possible.
To meet this requirement Siemens Energy has developed the new gas-insulated medium-voltage switchgear NX Plus C Wind. The gas-insulated switchgear deployed by Siemens to date for wind turbines operated at a voltage of 24 kilovolts (kV). The new NX Plus C Wind switchgear operates at a voltage of 36 kV. It is also of a more compact design than the previously built 36-kV Siemens switchgear and can be readily accommodated in the tower of a wind turbine.
Siemens developed its new medium-voltage switchgear NX Plus C Wind above all for deployment in wind farms. It is installed in the base of the wind turbine tower and therefore has to fit through the door. Because there is a limited amount of space in the tower the 36-kV switchgear is of a very compact design: Compared to a conventional 24-kV switchgear the new unit is 1000 mm deep and thus 250 mm shorter. Moreover, stringent demands were made of the switchgear's reliability. In the event of harsh weather conditions the switchgear in the wind turbines may often be inaccessible for days or even weeks.
In most applications the wind turbine with its generator supplies electrical energy at a voltage of 690 V. A downcircuit converter matches the frequency to that of the wind farm's network and ensures a stable voltage level. A transformer steps this up to 30 kV or 33 kV in order to keep transmission losses low. The wind turbine is ultimately connected with the wind farm's network via the circuit-breaker bay.
Siemens used its wealth of experience accumulated in wind farm projects for development of the NX Plus C Wind medium-voltage switchgear. The equipment units are manufactured at Siemens switchgear production plant in Frankfurt-Fechenheim. The company has been successfully deploying its gas-insulated medium-voltage switchgear for many years in wind farms. Customized switchgear are frequently designed in cooperation with wind turbine manufacturers and wind farm designers. In recent years Siemens has supplied more than 5000 medium-voltage switchgear units for wind farm applications – not only for numerous onshore projects but also for the first large offshore wind farms in Denmark such as Middelgrunden, Horns Rev and RÃ¸dsand. Medium-voltage switchgear for wind turbines are part of Siemens environmental portfolio, with which the company posted revenues totaling almost EUR19 billion in fiscal 2008. That is equivalent to about a quarter of Siemens total revenue.
The Siemens Energy Sector is a supplier of products, services and solutions for the generation, transmission and distribution of power and for the extraction, conversion and transport of oil and gas. In fiscal 2008 (ended September 30), the Energy Sector had revenues of about EUR22.6 billion and received new orders totaling about EUR33.4 billion and posted a profit of EUR1.4 billion. On September 30, 2008, the Energy Sector had a work force of about 83,500.
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