Kippzonen BSRN Scientific Solar Monitoring System Manual de usuario descargar pdf (Pagina 54)

Figure 4.9. Brusag two-axis active tracker. Active

tracking is accomplished by balancing the signals from

the quadrant sensor that is found on the flat of the

elevation disk. The pyrheliometer is a Kipp & Zonen

CH1.

(3) The base on which the tracker is to be placed must be stable. While active trackers and some

passive trackers are able to correct for a non-level surface, all trackers perform better if they

are mounted such that the instrument base is level. Trackers mounted on pedestals should

be levelled such that the vertical axis of the tracker, and not just the pedestal post, is

perpendicular to the horizon. A three-point base that allows easy adjustment is recommended.

The use of spring tensioners, lock washers, or bolts that are tightened using double nuts,

will reduce the problem of the connection between the mounting post and the tracker base

loosening and causing the tracker to tilt from level. The tracker should be rotated about the

vertical axis during the levelling process to ensure that the axis is vertical. A number of active-

tracking and computer-controlled passive tracking systems are capable of mathematically

correcting for out-of-level conditions so that solar tracking is maintained. These corrections,

however, do not correct for the tilt error of any pyranometer or pyrgeometer that is mounted

Figure 4.8. A single-axis synchronous motor tracker.

This model is an Eppley Model ST-1 Equatorial Mount.

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Kippzonen BSRN Scientific Solar Monitoring System Manual de usuario Pagina 54