Vaisala WAT12 Betriebsanweisung PDF herunterladen (Seite 9)

Chapter 2 ____________________________________________ Product Overview

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CHAPTER 2

PRODUCT OVERVIEW

This chapter introduces the WAA151 Anemometer features.

Introduction to WAA151 Anemometer

The WAA151 is an optoelectronic, fast-response, low-

threshold anemometer. In the cup wheel it has three light-

weight conical cups providing excellent linearity over the

entire operating range, up to 75 m/s. Rotated by the wind, a

chopper disc attached to the cup wheel’s shaft cuts an

infrared light beam 14 times per revolution, generating a

pulse train output from a phototransistor.

The output pulse rate can be regarded directly proportional

to wind speed, for example, 246 Hz = 24.6 m/s. For best

available accuracy, however, the characteristic transfer

function should be used, see section Specifications on page

25, to compensate for starting inertia and slight

overspeeding.

The heating element in the shaft tunnel keeps the

temperature of the bearings above the freezing level in cold

climates. Nominally it provides 10 W of heating power. It is

recommended to use a thermostat switch in the sensor cross

arm for switching the heating power on below +4 °C.

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Vaisala WAT12 Betriebsanweisung Seite 9