WEATHERPAK
®
EOC
Operations & Maintenance Manual
P/N: 0302-117-004 Rev. 0
6
2.4
Sensors
The system uses COTS (commercial off the shelf) sensors. A brief description of each sensor,
including sensor specifications, is provided in the following sections.
2.4.1 Wind Sensor
The wind sensor measures both horizontal wind speed and wind direction. The wind sensor is
mounted at the top of the WEATHERPAK
®
EOC so that disturbance from ground objects is
minimized. The wind sensor has an array of four equally spaced transducers in a horizontal plane
used to determine horizontal wind speed and direction. The measurement principle is based on
transit time, the time it takes for the ultrasound to travel from one transducer to another. Transit
time is affected by wind speed along the ultrasonic path. The transit time is measured in both
directions. For zero wind speeds, both the forward and reverse transit times are equal.
Table 2-1 – Wind Sensor Specification Data
Operating Temperature Range
-55 °C to +70 °C
Measuring Range
0 to 100 %RH
Wind Speed Range
0-75 m/s (168 mph)
Wind Speed Accuracy
+2% @12 m/s (27 mph)
Wind Speed Resolution
0.01 m/s
Wind Direction Range
0-359°
Wind Direction Accuracy
2°
Wind Direction Resolution
1°
2.4.2 Ambient Temperature / Optional Relative Humidity (AT/RH) Sensor
The AT/RH sensor is housed inside the sealed WEATHERPAK
®
EOC. The output voltage of the
probe ranges from 0 to 1 VDC. Output voltages from the sensor are sent to the ZENO
®
in the
WEATHERPAK
®
EOC for processing via an integral cable.
The radiation shield protects the sensor from incoming short wave solar radiation as well as
outgoing long wave radiation and provides excellent sensor contact with the incoming ambient air.
