Page 2
05103-45-90(E)
INSTALLATION
Proper placement of the instrument is very important. Eddies from
trees, buildings, or other structures can greatly influence wind
speed and wind direction observations. To get meaningful data
for most applications locate the instrument well above or upwind
from obstructions. As a general rule, the air flow around a structure
is disturbed to twice the height of the structure upwind, six times
the height downwind, and up to twice the height of the structure
above ground. For some applications it may not be practical or
necessary to meet these requirements.
FAILURE TO PROPERLY GROUND THE WIND MONITOR
MAY RESULT IN ERRONEOUS SIGNALS
OR TRANSDUCER DAMAGE.
Grounding the Wind Monitor is vitally important. Without proper
grounding, static electrical charge can build up during certain
atmospheric conditions and discharge through the transducers.
This discharge can cause erroneous signals or transducer failure.
To direct the discharge away from the transducers, the mounting
post assembly is made with a special antistatic plastic. It is very
important that the mounting post be connected to a good earth
ground. There are two ways this may be accomplished. First,
the Wind Monitor may be mounted on a metal pipe which is
connected to earth ground. The mounting pipe should not be
painted where the Wind Monitor is mounted. Towers or masts
set in concrete should be connected to one or more grounding
rods. If it is difficult to ground the mounting post in this manner,
the following method should be used. Inside the junction box
the terminal labeled EARTH GND is internally connected to the
antistatic mounting post. This terminal should be connected to
an earth ground (Refer to wiring diagram).
Initial installation is most easily done with two people; one to adjust
the instrument position and the other to observe the indicating
device. After initial installation, the instrument can be removed
and returned to its mounting without realigning the vane since
the orientation ring preserves the wind direction reference. Install
the Wind Monitor following these steps:
1. MOUNT WIND MONITOR
a) Place orientation ring on mounting post. Do Not tighten
band clamp yet.
b) Place Wind Monitor on mounting post. Do Not tighten band
clamp yet.
2. CONNECT SENSOR CABLE
a) Refer to wiring diagram located at back of manual.
3. ALIGN VANE
a) Connect instrument to an indicator.
b) Choose a known wind direction reference point on the
horizon.
c) Sighting down instrument centerline, point nose cone at
reference point on horizon.
d) While holding vane in position, slowly turn base until indicator
shows proper value.
e) Tighten mounting post band clamp.
f) Engage orientation ring indexing pin in notch at instrument
base.
g) Tighten orientation ring band clamp.
CALIBRATION
The Wind Monitor is fully calibrated before shipment and should
require no adjustments. Recalibration may be necessary after
some maintenance operations. Periodic calibration checks are
desirable and may be necessary where the instrument is used in
programs which require auditing of sensor performance.
Accurate wind direction calibration requires a Model 18112 Vane
Angle Bench Stand. Begin by connecting the instrument to a
signal conditioning circuit which has some method of indicating
wind direction value. This may be a display which shows wind
direction values in angular degrees or simply a voltmeter
monitoring the output. Orient the base so the junction box faces
due south. Visually align the vane with the crossmarkings and
observe the indicator output. If the vane position and indicator
do not agree within 5°, adjust the potentiometer coupling inside
the main housing. Details for making this adjustment appear
in the MAINTENANCE, POTENTIOMETER REPLACEMENT,
outline, step 7.
It is important to note that, while the sensor mechanically rotates
through 360°, the full scale wind direction signal from the signal
conditioning occurs at 355°. The signal conditioning electronics
must be adjusted accordingly. For example, in a circuit where 0
to 1.000 VDC represents 0° to 360°, the output must be adjusted
for 0.986 VDC when the instrument is at 355°. (355°/360° X 1.000
volts = 0.986 volts)
Wind speed calibration is determined by propeller pitch and the
output characteristics of the transducer. Calibration formulas
showing wind speed vs. propeller rpm and output frequency are
included below. Standard accuracy is ± 0.3 m/s (0.6mph). For
greater accuracy, the sensor must be individually calibrated in
comparison with a wind speed standard. Contact the factory or
your supplier to schedule a NIST (National Institute of Standards
& Technology) traceable wind tunnel calibration in our facility.
To calibrate wind system electronics using a signal from the
instrument, temporarily remove the propeller and connect an
Anemometer Drive to the propeller shaft. Apply the appropriate
calibration formula to the calibrating motor rpm and adjust the
electronics for the proper value. For example, with the propeller
shaft turning at 3600 rpm adjust an indicator to display 17.6 meters
per second [3600 rpm X 0.00490 (m/s)/rpm =17.6 m/s]
Details on checking bearing torque, which affects wind speed and
direction threshold, appear in the following section.
CALIBRATION FORMULAS
Model 05103 Wind Monitor
WIND SPEED vs PROPELLER RPM
m/s
= 0.00490 x rpm
knots = 0.00952 x rpm
mph = 0.01096 x rpm
km/h = 0.01764 x rpm
WIND SPEED vs OUTPUT FREQUENCY
m/s
= 0.0980 x Hz
knots = 0.1904 x Hz
mph = 0.2192 x Hz
km/h = 0.3528 x Hz
