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How does it work? The VSDS system is integrated with the control system of the turbine. If the unit registers shadow flicker beyond a certain threshold, it pauses the blades to avoid the strobing effect on nearby properties. The equipment comprises two sensors, fitted to the east and west aspects of the turbine. A shadow controller unit measures the difference in intensity between those two readings and calculates how pronounced a shadow is at any given moment. The sensors are: · Heated to prevent freezing in conditions as low as -38oC. · Resistant to ground reflection for consistent results · Magnetised for cost-effective installation Shadow controllers are uniquely configured for each turbine. They are programmed with the locations of neighbouring properties, as well as timetables indicating when shadow flicker must be avoided. Don’t be in the dark about shadows The intensity of shadow casting is primarily dependent on four factors: · The angle and position of the sun in relation to the turbine and the property affected · The distance from the turbine to the property · The size of the rotor · The hub height Based on these values, WindPro software is used to calculate values for each turbine. These are a ‘theoretical’ worst-case shadow scenario, and an ‘actual’ shadow scenario. The latter takes into account live factors such as the weather conditions and whether or not the turbine is running These two values are important because in many markets they can be critical for planning permission. In Germany, for example, wind farms are limited to 30 hours of ‘theoretical’ shadow casting per year, but only eight hours per year of ‘actual’ shadow casting. The sensors are magnetised for cost-effective installation. © 2012 Vestas Wind Systems A/S. All rights reserved. This document was created by Vestas Wind Systems A/S on behalf of the Vestas Group and contains copyrighted material, trademarks and other proprietary information. This document or parts thereof may not be reproduced, altered or copied in any form or by any means without the prior written permission of Vestas Wind Systems A/S. All specifications are for information only and are subject to change without notice. Vestas Wind Systems A/S does not make any representations or extend any warranties, expressed or implied, as to the adequacy or accuracy of this information. This document may exist in multiple language versions. In case of inconsistencies between language versions the English version shall prevail. Certain technical options, services and wind turbine models may not be available in all locations/countries. 01/2012-EN

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