Casella CEL Automatic weather station - Manual (Page 20)

3.1.2 Humidity Sensor Specification
Sensor type: Capacitative
Measuring range: 0 - 100% RH
Calibrated accuracy: ±3% RH
Hysteresis: ±1%
Linearity: ±1.5% RH between 5% - 95% RH
Time constant: <10 s between 10% and 90% RH
Operating temperature: -25° to +80°C
3.1.3 Air Temperature & Humidity - Sensus Channel
Configurations
Description Air temperature Humidity
Units o C %RH
Type Analog Analog
Information Single ended
Gain x 1
No current source Single ended
Gain x 1
No current source
Display Format +##.# ###.#
Polynomial -40, 100 0, 100
Enabled Yes Yes
Logged Yes Yes
Minimum Limit -40.0 0.0
Maximum Limit +60 100.0
3.2 Wind Speed Sensor
The sensitive three cup anemometer is
mounted at one end of the cross-arm. The
rotational speed is monitored using an
infra-red light source, interrupter and optical
sensor that provides 20 pulses from 0 to 5 V
per revolution. This non-contacting design
can measure wind speeds up to 75 m/sec.
The instrument has an anodised
aluminium alloy outer case that offers a
durable, all-weather construction suitable for
installation in harsh environments.
An output from this sensor is led to
a terminal box on the sensor cross arm, from
where a single sensor cable is taken to the
7-pin socket on the bottom panel of the environmental case.
3.2.1 Wind Speed Sensor Specification
Part number: 178031C
Sensor type: Three cup anemometer
Transducer: Optical interrupter
Maximum wind speed: 75 m/s
Starting velocity: Typically 0.3 m/s
Distance constant: Typically 3.5 m/s
Time constant: Typically <0.5 s
Resolution: 7.84 cm
Non-linearity: <±0.6 %
Accuracy: ±0.3 m/s below 3 m/s
Standard Sensors
01057
Wind speed sensor
Page 20 of 34
Automatic Weather Station
Assembly & Commissioning Handbook