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MODEL 05305
WIND MONITOR - AQ
WIND SPEED SPECIFICATION SUMMARY
Range
0 to 50 m/s (112 mph)
Sensor
20 cm diameter 4-blade helicoid
propeller carbon fiber thermoplastic
Distance Constant
2.1 m (6.9 ft.) for 63% recovery
Threshold Sensitivity
0.4 m/s (0.9 mph)
Transducer
Centrally mounted stationary coil,
2K ohm nominal DC resistance
Transducer Output
AC sine wave signal induced by rotating
magnet on propeller shaft. 80 mV p-p at
100 rpm. 8.0 V p-p at 10,000 rpm.
Output Frequency
3 cycles per propeller revolution
(0.102 m/s per Hz)
WIND DIRECTION (AZIMUTH) SPECIFICATION SUMMARY
Range
360° mechanical, 355° electrical
(5° open)
Sensor
Balanced vane, 48.3 cm (19 in) turning
radius.
Damping Ratio
0.45
Delay Distance
1.2 m (3.9 ft) for 50% recovery
Threshold Sensitivity
0.5 m/s (1.0 mph) at 10° displacement
0.7 m/s (1.6 mph) at 5° displacement
Damped Natural
Wavelength
4.9 m (16.1 ft)
Undamped Natural
Wavelength
4.4 m (14.4 ft)
Transducer
Precision conductive plastic potentiometer,
10K ohm resistance (±20%), 0.25%
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 azimuth
angle with regulated excitation voltage
applied across potentiometer.
GENERAL
Operating temperature: -50 to 50°C (-58 to 122°F)
INTRODUCTION
The Wind Monitor measures horizontal wind speed and direction.
Developed for air quality applications, it is accurate, sensitive, and
corrosion resistant. The main housing, nose cone, propeller, and
other internal parts are injection molded U.V. stabilized plastic. The
tail section is lightweight expanded polystyrene. Both the propeller
and vertical shafts use stainless steel precision grade ball bearings.
Bearings have shields to help exclude contamination and moisture.
Propeller rotation produces an AC sine wave signal with
frequency proportional to wind speed. This AC signal is induced in a
stationary coil by a six pole magnet mounted on the propeller shaft.
Three complete sine wave cycles are produced for each propeller
revolution.
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 azimuth angle.
The instrument mounts on standard one inch pipe, outside diameter
34 mm (1.34"). An orientation ring is provided so the instrument can
be removed for maintenance and reinstalled without loss of wind
direction reference. Both mounting post assembly and orientation
ring are secured to the mounting pipe by stainless steel band clamps.
Electrical connections are made in a junction box at the base. A
variety of devices are available for signal conditioning, display, and
recording of wind speed and direction.
INITIAL CHECKOUT
When the Wind Monitor is unpacked it should be checked carefully
for any signs of shipping damage.
Remove the plastic nut on the propeller shaft. Install the propeller on
the shaft with the serial number of the propeller facing forward (into
the wind). The instrument is aligned, balanced and fully calibrated
before shipment; however, it should be checked both mechanically
and electrically before installation. The vane and propeller should
easily rotate 360° without friction. Check vane balance by holding
the instrument base 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 potentiometer requires a stable DC excitation voltage. Do not
exceed 15 volts. When the potentiometer wiper is in the 5° 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: Young signal conditioning devices
clamp the signal to excitation level. Avoid a short circuit between
the azimuth signal line and either the excitation or reference lines.
Although there is a 1K ohm 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 an indicator as
shown in the wiring diagram and check for proper wind speed
and azimuth values. To check wind speed, temporarily remove the
propeller and connect the shaft to an Anemometer Drive. Details
appear in the CALIBRATION section of this manual.
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
Page 1
05305-90(T)
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