Casella CEL Automatic weather station - Manual (Page 27)

The installed device may be specified as optimised for either rain, frost
or dew. The rain sensing version incorporates a heater to dry the surface once
rain has ceased, and also to eliminate it’s sensitivity to the formation of dew.
The sensor will respond to a single 1 mm diameter droplet of distilled
water.
3.9.1 Leaf Wetness Sensor Specification
Part number: 187081B
Transducer: Three element carbon electrode
Length: 150 mm
Supply voltage: 9 - 18 V DC
Power consumption: 5 mA Max
Output Calibration Wet =1.5 V approximately
Dry = 0 V
Sensing area 15 x 30 mm
Operating temp. -10°C to +55°C
Cable: 3 m cable supplied
3.9.2 Leaf Wetness - Sensus Channel Configuration
Description Wetness
Units None
Type Analog
Information Single ended
Gain x 1
No current source
Display Format ###.#
Polynomial 0, 1
Enabled Yes
Logged Yes
Minimum Limit 0
Maximum Limit 2.5
3.10 Grass Temperature Sensor
The grass minimum temperature
measurement is achieved by locating a
shielded thermometer at a fixed height
above the grass, supported on a small frame.
3.10.1 Grass Temperature Sensor Specification
Part number: 120650B
Sensor type: Semi conductor current generator
02025
Figure 20: Grass temperature sensor
Page 27 of 34
Automatic Weather Station
Assembly & Commissioning Handbook