Casella CEL Nomad portable weather station - Manual (Page 46)

The bucket assembly is adjusted to
tip each time an amount of water
proportional to 0.2 mm of rainfall has
collected in one or other side of the bucket.
Therefore, each time the bucket tips, a signal
proportional to precisely 0.2 mm of rainfall is
sent to the logger.
The gauge has a body and funnel
constructed of aluminium alloy, with an
accurately machined “Septum Ring”.
The aluminium base plate is
equipped with levelling screws and a spirit
level for precise adjustment.
6.7.1 Rainfall Sensor Specification
Part number: 187060D
Transducer: Tipping Bucket
Aperture: 400 cm²
Resolution: 0.2 mm per tip
Accuracy: ±1%
Capacity: Unlimited
Operating temp: 1°C to 85°C
Supply Voltage: 7 - 20 V DC (supplied from environmental
case)
Power Consumption: Typically 2-3 mA
Output calibration: Debounced 0 to 5 V pulses.
Cable: 9 m cable supplied
6.8 Soil Temperature Sensor
This is an additional sensor available for use
with “Special” Nomad Weather Systems.
The soil temperature sensor is
connected by cable to an auxilliary junction
box. Clip this box to the lower part of the
tripod, and connect the output cable to the
7-pin socket in the bottom panel of a special
system environmental case.
The sensor is designed to be installed at any depth, by digging a small
hole to the required depth, locating the sensor then back filling. This technique
avoids the requirement for multi-length probes, and is simpler and more reliable
than attempting to insert long thin probes into hard soil. The sensor may be
used to measure ground surface temperature by installing in the top 1 cm of the
soil sample.
6.8.1 Soil Temperature Sensor Specification
Part number: 120620B
Sensor type: Semi conductor current generator
Measuring range: -40°C to 60°C
Calibrated accuracy: ±0.5°C between -20 to + 50°C
Supply voltage: 7 to 15 V
Power consumption: Typically <1 mA
Output calibration: Nominally 1.5 V at 0°C and 1.8 V at 50°C
Standard Sensors
02024
Figure 16: Tipping bucket rainfall
sensor
01061
Figure 17: Soil temperature sensor
Page 46 of 68
NOMAD Portable Weather Station
Users Handbook