8
2.4.2 Wind Speed and Direction Sensor
Connect the wind sensor cable to the terminal strip on the data acquisition module. This
sensor has a four conductor shielded cable. The RED wire is connected to the +5 REF
terminal; The BLACK wire is connected to a GROUND terminal; the GREEN wire (wind
direction signal) is connected to the A7 terminal and the WHITE wire (wind speed
signal) is connected to the P1 terminal.
The wind vane requires alignment of the “dead band” or potentiometer gap to North,
either magnetic or true North, to obtain valid measurements. Alignment can be done at
ground level allowing easier installation of the sensor, but it must be checked again
after the sensor has been fully installed.
The wind sensor base is used to orient the wind vane to North. Normally, wind direction
sensors are aligned to true North, rather than magnetic North. True North can be found
by reading a magnetic compass and applying the correction for magnetic declination,
where magnetic declination is the number of degrees between true North and magnetic
North.
Alignment involves creating an imaginary line running
through the wind sensor from North to South. When this
line has been established, the mounting base of the sensor
is rotated until the screw head in the base and the screw
hole that is just above it in the sensor body both point
toward North. Rotate the sensor housing until the two
screw holes point toward the North.
Call up the main menu (Figure 3, Page 9) on the display
terminal by pressing "m" two times. Press "2" for output
observations. Then press "1" for observation display
(Figure 4, Page 9).
Turn the anemometer cups by hand, wait for the screen to update, every five seconds,
and note the wind speed displayed on the screen. (It will read about 7 to 12 mph.) This
value should change as you spin the cups.
Rotate the vane tail until the counter-weight nose also points to North and is in line with
the two screw holes. Check the output signal of the direction sensor. If the alignment is
correct, the output signal should indicate North (0 or 360 degrees). Correct the sensor
base rotation to bring the reading into agreement with the compass. When the
alignment appears to be good, secure the sensor base set screws to the mast. Turn the
vane in increments around the full 360 degrees, noting the change in the wind direction
readings. These should agree with the position of the vane.
Wind coming from:
Equals:
North
0°
East
90°
South
180°
West
270°
Summary of Contents for 110-WS-16
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