Campbell LWS, Инструкция по эксплуатации

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LWS Dielectric Leaf Wetness Sensor
6. After selecting the sensor, click at the left of the screen on Wiring
Diagram to see how the sensor is to be wired to the datalogger. The
wiring diagram can be printed out now or after more sensors are added.
7. Select any other sensors you have, then finish the remaining
Short Cut
steps to complete the program. The remaining steps are outlined in Short
Cut Help , which is accessed by clicking on Help | Contents |
Programming Steps .
8. If
LoggerNet
,
PC400
,
RTDAQ
, or
PC200W
is running on your PC, and the
PC to datalogger connection is active, you can click
Finish
in Short Cut
and you will be prompted to send the program just created to the
datalogger.
9. If the sensor is connected to the datalogger, as shown in the wiring
diagram in step 6, check the output of the sensor in the datalogger support
software data display to make sure it is making reasonable measurements.
5. Overview
5.1 Measurement
The LWS measures the dielectric constant of a zone approximately 1 cm from
the upper surface of the sensor. The dielectric constant of water (≈80) and ice
(≈5) are much higher than that of air (≈1), so the measured dielectric constant
is strongly dependent on the presence of moisture or frost on the sensor
surfaces. The sensor outputs a mV signal proportional to the dielectric of the
measurement zone, and therefore proportional to the amount of water or ice on
the sensor surface.
5.2 Leaf Mimicry
The LWS is designed to approximate the thermodynamic properties of most
leaves. If the specific heat of a typical leaf is estimated at 3750 J kg
–1
K
–1
,
density estimated at 0.95 g/cm 3 , and thickness estimated at 0.4 mm, then the
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