Campbell Scientific 03002, 03101, and 03301 R. M. Young Wind Sentry Sensors - Manual (Page 34)

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03002-5-90(D)
MODEL 03002-5
WIND SENTRY
INCLUDES MODELS 03102 & 03302
INTRODUCTION
The Wind Sentry Anemometer and Vane measure horizontal wind
speed and wind direction. The small size, simplicity, and corrosion
resistant construction provide a professional quality instrument at
a modest cost. The cup wheel and vane shafts use stainless steel
precision instrument grade ball bearings which are lubricated with a
wide temperature range high quality instrument oil. Standard bearings
have light contacting seals to exclude contamination and help retain
lubricant for longer service life.
Cup wheel rotation produces an AC sine wave voltage signal with
frequency directly proportional to wind speed. This AC signal is
induced in a stationary coil by a two pole ring magnet mounted on
the cup wheel shaft. One complete sine wave cycle is produced for
each cup wheel revolution.
Wind vane position is transmitted by a 10K ohm precision conductive
plastic potentiometer which requires a regulated excitation voltage.
With a constant voltage applied to the potentiometer, the output signal
is an analog voltage directly proportional to wind direction angle.
The instrument mounts on standard 1 inch pipe, outside diameter
34mm (1.34") and is supplied with a crossarm and junction box for
cable connections. Wind Sentry anemometers and windvanes are
available separately with similar mounting and junction box.
INITIAL CHECK-OUT
When the Wind Sentry is unpacked, check it carefully for any signs
of shipping damage. Place the cup wheel on the anemometer shaft
and secure it by tightening the set screw on the side of the hub. The
instrument is aligned, balanced, and fully calibrated before shipment;
however, it should be checked both mechanically and electrically
before installation. The vane and cup wheel should easily rotate
360° without friction. Check vane balance by holding the instrument
so the vane surface is horizontal. It should have near-neutral torque
without any particular tendency to rotate. A slight imbalance will not
degrade performance.
The wind direction potentiometer requires a stable DC excitation
voltage. Do not exceed 15 volts. When the potentiometer wiper is
in the 8° deadband region, the output signal is "floating" and may
show varying or unpredictable values. To prevent false readings,
signal conditioning electronics should clamp the signal to excitation
or reference level when this occurs. Note: All YOUNG signal
conditioning devices clamp the signal to excitation level. Avoid
a short circuit between the wind direction signal line and either the
excitation or ground reference lines. Although there is a current
limiting resistor in series with the wiper for protection, damage to the
potentiometer may occur if a short circuit condition exists.
Before installation, connect the instrument to a signal conditioning
device as shown in the wiring diagram and check for proper wind
speed and direction values. To check wind speed, temporarily remove
the cup wheel and connect an Anemometer Drive to the cup wheel
shaft. Details appear in the CALIBRATION section.
INSTALLATION
Proper placement of the instrument is very important. Eddies from
trees, buildings, or other structures can greatly influence wind
speed and direction observations. To get meaningful data for most
applications, locate the instrument well above or upwind of such
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 twice the height of the structure above ground.
For some observations it may not be practical or necessary to meet
these guidelines.
WIND SPEED SPECIFICATION SUMMARY
Range 0 to 50 m/s (112 mph), gust survival 60
m/s (134 mph)
Sensor 12 cm diameter cup wheel assembly,
40 mm diameter hemispherical cups
Turning Factor 75 cm (2.46 ft)
Distance Constant 2.3 m (7.5 ft) (63% recovery)
Threshold 0.5 m/s (1.1 mph)
Transducer Stationary coil, 1300 ohm nominal resistance
Transducer Output AC sine wave signal induced by rotating
magnet on cup wheel shaft 100 mV p-p at
60 rpm. 6V p-p at 3600 rpm.
Output Frequency 1 cycle per cup wheel revolution.
WIND DIRECTION (AZIMUTH) SPECIFICATION SUMMARY
Range 360° mechanical, 352° electrical (8° open)
Sensor Balanced vane, 16 cm turning radius.
Damping Ratio 0.2
Delay Distance (50% recovery) 0.5 m (1.6 ft)
Threshold 0.8 m/s (1.8 mph) at 10° displacement
Transducer Precision conductive plastic potentiometer,
10K ohm ±20% resistance 1.0% linearity,
life expectancy 50 million revolutions Rated
1 watt at 40°C, 0 watts at 125°C
Transducer Excitation Requirement Regulated DC voltage, 15
VDC max
Transducer Output Analog DC voltage proportional to wind
direction angle with regulated excitation
voltage applied across potentiometer
GENERAL
Operating Temperature -50 to 50°C (-58 to 122°F)