Priva Weather Station Wsc11; Principle - Priva Compass Installation Manual

Priva weather station WSC11

The Priva weather station WSC11 integrates all the measurements that are relevant to the horticulture
industry in a single compact station.
The following measurements are available when the weather station is used with the Compass:
• Wind speed
• Wind direction
• Global radiation (Radiation sensor)
• Rain alarm
• Outside temperature
• Relative humidity

Principle

Wind speed / wind direction
Wind measurement is based on the hot wire principle. The bottom is equipped with a heated
cylindrical sensor. The supplied heat energy is a measure of wind speed.
The metal cylinder contains 4 temperature-measuring resistors. These resistors are thermally coupled
with the cylinder and positioned according to the 4 points of the compass. When an incident flow
affects the cylinder as a function of the wind direction, this is accompanied by a temperature gradient
which is registered by the measuring resistors. The relationships between the 4 temperature values
are used to calculate the wind direction.
Light
The light measurement is carried out via 4 silicium photo sensors, which are aligned to the 4 cardinal
directions in the mean elevation angle (40°).
Twilight
Twilight is calculated from the sum of the 4 measuring values of the direction-independent light
sensors.
Global irradiance
A silicon PIN photodiode is used to measure global irradiance. The sensor is positioned horizontally
and registers the diurnal values of the solar irradiation intensity.
Precipitation
The detection of precipitation is based on capacitance measurement. The sensor is installed in the
housing cover. An integrated heating system adjusts the sensor area to an overtemperature in
relation to the ambient temperature. This overtemperature (approximately 2K) prevents bedewing
of the sensor surface. The thermal output is increased with precipitation. This accelerates drying of
the sensor, allowing the time at which precipitation ended to be identified more accurately.
Air temperature
A PT1000 measuring resistor is used to measure the air temperature. The sensor is mounted on a
flexible printed board and positioned in the lower section of the housing.
Installing Priva Compass - 00.014
Priva weather station WSC11
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