Whether it is a photovoltaic (PV), a concentrating photovoltaic (CPV), or a concentrating solar power (CSP) system, solar power plants work particularly efficiently if their mirrors, collectors and PV modules track the course of the sun. The more precise and trouble-free they are, the more efficient and profitable the plant. Schaeffler has taken another step towards system integration for precise solar tracking in azimuth and elevation axes by offering the linear actuator as a complete unit from one source in addition to bearings for the swivel drives.
A complete mechatronic system
The INA linear actuator responsible for the stroke motion in the elevation axis was specially developed and designed by Schaeffler’s linear technology business unit for operation in the harsh conditions of the tracking systems of solar power plants. It is designed for dynamic loads of up to five kN and static loads of up to 15 kN. The actuator can reach a stroke travel of up to 1000 mm at a stroke speed of five mm/sec. Its innovative design and high flexibility mean that the length (stroke) and connection can always be matched exactly to the customer’s individual plant.
The complete mechatronic system comprises the rolling bearings for the individual bearing positions, the screw drive spindle and spindle nut, the extension tube, the compact housing with housing cover, the seal, the drive technology (motor and gearbox unit), the sensors and the rod end for connecting the actuator.
The linear actuator is designed for operation in the harsh environmental conditions of solar power plants. It is low maintenance due to the encapsulated housing, a reduced number of perfectly sealed joints, and the integrated motor and gearbox unit and entire drive technology. The components used for sealing the actuator according to protection class IP66 prevent the ingress of contamination, water or sand. In conjunction with the low maintenance or completely maintenance-free components and bearing supports, the linear actuator has an operating life of up to 25 years. The high precision axes ensure that the solar power plant generates an optimum power output on a permanent basis. This linear actuator concept can also be adapted for other sectors or applications depending on the technical and geometrical requirements.
Bearing supports for precise swivelling motion
INA angular contact roller bearings AXS and FAG tapered roller bearings in X-life quality are particularly suitable for supporting the swivel drives responsible for adjusting the azimuth axis. They have a high load carrying capacity and can be set clearance-free. This is an important prerequisite for high rigidity and positioning accuracy and therefore the efficiency of the entire tracking system.
Series AXS rolling bearings have cylindrical rollers and raceways that are arranged at an angle to the bearing axis. The roller and cage assemblies are comprised of cylindrical rollers that are snapped into high rigidity plastic cages with very close spacing. This means that high load ratings are achieved. A special feature of the AXS series is the conical bearing rings. They are manufactured using forming methods, which makes them very cost-effective. In addition, turned bearing seats are sufficient for supporting the bearing rings manufactured using forming methods. This reduces costs for the adjacent construction.
For more information contact Coenie van Deventer, Bearings International, +27 (0)11 899 0101, [email protected], www.bearings.co.za
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