GHM DeltaOHM HD51.3D Series, Operating Manual

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HD51.3D…
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V2.0
For open-space installations, the instrument can be installed using the HD2005.20 (max.
height 225 cm) or HD2005.20.1 (max. height 335 m) tripod.
If the instrument is installed on a building, the height of the instrument should be at least 1.5
times the minimum value between the height of the building and the roof longest diagonal.
5.1 A
LIGNMENT OF THE INSTRUMENT
If the instrument is equipped with compass (option A in the instrument code), wind speed and
direction measurements are automatically compensated and referred to magnetic North ,
even if alignment to North is not performed. This allows obtaining accurate measurements
even in case of mobile installations.
If the instrument is not equipped with compass (or the compensation performed by the sensor
is disabled), it is necessary to align the instrument during installation. The housing is provided
with a reference to facilitate the alignment: an arrow at the bottom of the ultrasonic sensors
supporting plate for versions with housing in technopolymer, two notches on the side for ver-
sions with housing in aluminium alloy. The reference must be aligned with the
geographical
North .
Housing in technopolymer Housing in aluminium alloy
If a magnetic compass is used for alignment, take into account that the geographic North dif-
fers from the magnetic North indicated by the compass. The difference, named
magnetic dec-
lination , depends on the area where the instrument was installed (for example, about 15° in
North-America and less than 3° in Europe).
To align an instrument equipped with compass but with compensation function disabled, it is
possible to use for the alignment the information provided by the sensor by connecting the in-
strument to a PC (see the following chapters for the communication protocols) and rotating the
instrument on its vertical axis until the compass measurement is 0.0° ± 0.1°.
If wind speed and direction values are given in polar coordinates, 0° angle corresponds to a
wind coming from North.
Take into account that the instrument measures the wind direction with respect to the reference
on the housing if it is not equipped with compass or the compensation performed by the sensor
is disabled.
Arrow for
alignment to North
Ultrasonic sensors
supporting plate
Notches for
alignment to North