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Pitch brakes hold power in wind turbines

Pitch brakes hold power in wind turbines

The ERS Series of electrically-released, spring-engaged brakes serve as pitch brakes for wind turbine applications that require both “static” holding power and the ability to withstand high inertia dynamic stops in an emergency situation. Each of the three blades on a typical turbine can be individually positioned (rotated) to achieve maximum efficiency while operating in changing wind conditions. An ERS68 brake is used on each of the three blades.

The electromagnetic brake is mounted outboard of an inductive encoder, which is mounted to the back of a motor to position the blades to the proper pitch. In normal use, the brake functions as a static brake to hold the blades from rotating in a power-off situation during routine maintenance or for other reasons.

However, the design spec for one major manufacturer requires the brake to also be able to make 1,000 fully loaded dynamic stops during its service life. The largest in the ERS Series, the 11.3-lb ERS68, has been tested to a capacity of more than 20,000 fully-loaded dynamic stops, surpassing the design spec by a factor of 20. The brake offers 100 ft. lb of static torque with a maximum of 2,000 rpm and a brake release time of 0.2 sec.

The new blade pitch brakes offer a one-piece design, and are fully-enclosed and painted to withstand extreme environmental conditions such as salt-spray, condensation, and water. Previous to the new design, pitch brake models have used two-piece designs that require an adapter plate, extra fasteners, and an external boot-type seal in the gap between the brake and the adapter plate to prevent contamination. For more information, visit Warner Electric.

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