Product overview, Introduction to waa151 anemometer, Chapter 2, product overview, introduces the waa151 – Vaisala WAA151 User Manual
Page 9: Anemometer features, Chapter 2
Chapter 2 ____________________________________________ Product Overview
VAISALA___________________________________________________________7
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.