Xylem H-375 04101 WIND MONITOR-JR - Manual (Page 10)

Page 1
GENERAL
Operating Temperature: -50 to 50°C (-58 to 122°F)
INTRODUCTION
The Wind Monitor measures horizontal wind speed and direction.
Originally developed for ocean data buoy use, it is rugged and
corrosion resistant yet accurate and light weight. The main
housing, nose cone, propeller, and other internal parts are
injection molded U.V. stabilized plastic. Both the propeller and
vertical shafts use stainless steel precision grade ball bearings.
Bearings have light contacting teflon seals and are filled with a
wide temperature range grease to help exclude contamination
and moisture.
Propeller rotation produces an AC sine wave signal with fre-
quency 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 wind
direction 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 the mounting post
assembly and the 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 so the serial number on the propeller faces forward
(into the wind). Engage the propeller into the molded ribs on the
propeller shaft 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
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 exci-
tation or reference level when this occurs. NOTE: 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 reference lines. Although there is a 1K
ohm current limiting resistor in series with the wiper for protec-
tion, damage to the potentiometer may occur if a short circuit
condition exists.
WIND SPEED SPECIFICATION SUMMARY
Range 0 to 60 m/s (130 mph), gust survival
100 m/s (220 mph)
Sensor 18 cm diameter 4-blade helicoid
propeller molded of polypropylene
Pitch 29.4 cm air passage per revolution
Distance Constant 2.7 m (8.9 ft.) for 63% recovery
Threshold Sensitivity 1.0 m/s (2.2 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
(0.0980 m/s per Hz)
WIND DIRECTION (AZIMUTH) SPECIFICATION SUMMARY
Range 360° mechanical, 355° electrical
(5° open)
Sensor Balanced vane, 38 cm (15 in)
turning radius.
Damping Ratio 0.3
Delay Distance 1.3 m (4.3 ft) for 50% recovery
Threshold Sensitivity 1.1 m/s (2.5 mph) at 10° displacement
Damped Natural
Wavelength 7.4 m (24.3 ft)
Undamped Natural
Wavelength 7.2 m (23.6 ft)
Transducer Precision conductive plastic potetio-
meter, 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.
MODEL 05103
WIND MONITOR