062-12 Lohr, 2012-09-18

Two reliable partners


Image source: e.n.o. energy GmbH

As safety functions, electromechanical and hydraulic rotor blade drives from Rexroth minimize the downtimes of wind turbines

Increasing competitive and cost pressure demands high availability of wind turbines. The safety functions of modern pitch systems minimize downtimes, thus increasing the availability and energy yield of plants. Furthermore, compliance with ever stricter legal guidelines with regard to safety is also required. The electromechanical and hydraulic pitch drives from Rexroth offer manufacturers two solutions to meet these requirements.

Safety plays an increasingly important role in the development of new plant concepts. For example, in the risk assessments under European Machinery Directive 2006/42/EC or ISO 13849-1 required for the certification of new wind turbines in Europe, “Performance Level d” or “Safety Integrity Level SIL 2” will in future be required for safety-related functions.

The pitch system plays an important role in the safety of the plant. For the first time, the safety inverter in the e-pitch solutions from Rexroth now allows emergency rotor movement if an inverter fails, even with AC motors. This is meant to meet the requirements of the standard, and increases the safety of wind turbines. The emergency rotor movement speed is controlled and can be configured as required. In the previous solutions with heterogeneous individual systems, the failure of an inverter leads to the shutdown of the wind turbine. Furthermore, if an inverter fails, the intelligent networking of the electronics allow an intact inverter to take over the functions of the failed inverter to drive the axle.

By using special cables with a lightning-resistant external sheath and an internal mesh for electromagnetic compatibility, induced overvoltages from lightning strikes are avoided. This means overvoltage protection elements are no longer required, reducing maintenance costs.

As with the e-pitch solutions, the hydraulic pitch adjustment from Rexroth also ensures that emergency rotor movement is possible in the event of power or pressure loss. Compared to the e-pitch solution, however, the hydraulic pitch adjustment requires fewer components. Since the emergency chain is purely mechanical, lightning strikes are not critical for safety.

Rexroth at HUSUM WindEnergy: Hall 3, Stand 3D12

Bosch Rexroth AG is one of the world’s leading specialists in the field of drive and control technologies. Under the Rexroth brand name, the company supplies more than 500,000 customers with tailored solutions for driving, controlling, and moving. Bosch Rexroth is a partner for Mobile Applications, Machinery Applications and Engineering, Factory Automation and Renewable Energies. The company provides customized solutions tailored to the needs and specifications of each individual market. As The Drive & Control Company, Bosch Rexroth develops, produces, and sells components and systems in over 80 countries. As part of the Bosch Group, Bosch Rexroth and its 38,400 associates generated approximately 6.4 billion euros in revenue in 2011.

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The Bosch Group is a leading global supplier of technology and services. According to preliminary figures, more than 300,000 associates generated sales of 51.4 billion euros in the areas of automotive and industrial technology, consumer goods, and building technology in fiscal 2011. The Bosch Group comprises Robert Bosch GmbH and its more than 350 subsidiaries and regional companies in some 60 countries. If its sales and service partners are included, then Bosch is represented in roughly 150 countries. This worldwide development, manufacturing, and sales network is the foundation for further growth. Bosch spent more than 4 billion euros for research and development in 2011, and applied for over 4,100 patents worldwide. With all its products and services, Bosch enhances the quality of life by providing solutions which are both innovative and beneficial.

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Susanne Herzlieb
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