Campbell-scientific 014A Met One Wind Speed Sensor Manuel d'utilisateur télécharger pdf (Page 33)

Appendix D. Theory of Operation

D.1 Mechanical

The sensor’s cup assembly consists of three aluminum cups mounted on a cup

assembly hub. A stainless steel shaft, which rotates on precision-sealed ball

bearings, connects the cup assembly to a magnet assembly. When the shaft is

rotated, the turning magnet assembly causes a reed switch to close. There are

two contacts (reed switch closures) per revolution. The frequency of closures

is linear from threshold to 45 m s

–1

D.2 Calibration

The 014A sensor has a threshold speed of 0.447 m s

–1

and follows the equation:

V = 0.447 + f/1.250 where

V = wind speed (m s

–1

), and

f = output frequency (hz,)

or, V = 1.0 + f/0.5589

where V = wind speed (mph), and

f = output frequency (hz.)

D-1

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Campbell-scientific 014A Met One Wind Speed Sensor Manuel d'utilisateur Page 33