Campbell Scientific 03002, 03101, and 03301 R. M. Young Wind Sentry Sensors - Manual (Page 35)

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03002-5-90(D)
FAILURE TO PROPERLY GROUND THE WIND SENTRY
MAY RESULT IN ERRONEOUS SIGNALS
OR TRANSDUCER DAMAGE.
Grounding the Wind Sentry 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 instrument is made with a special anti-static
plastic. It is very important that the instrument be connected to a good
earth ground. There are two ways this may be accomplished. First,
the Wind Sentry may be mounted on a metal pipe which is connected
to earth ground. The mounting pipe should not be painted where the
Wind Sentry 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 anti-static housings. 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.
When anemometer and vane are mounted on the same cross arm
(Model 03002), the azimuth potentiometer has been aligned at the
factory such that the mounting cross arm should be oriented North-
South with the vane on the North end.
To install the Wind Sentry, follow these steps:
1. MOUNT WIND SENTRY
a) Connect sensor cable to Wind Sentry junction box.
b) Place Wind Sentry on mounting post. Do Not tighten
band clamp yet.
c) Connect sensor cable to indicator.
2. ALIGN VANE
a) Select a known azimuth reference point on the horizon.
b) Sighting down vane centerline, point counterweight at
reference point on horizon.
c) While holding vane in position, slowly turn base until
indicator displays proper value.
d) Tighten mounting post band clamp.
CALIBRATION
The Wind Sentry 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.
For wind direction calibration, the following method can yield an
accuracy of ±5° or better if carefully done. Begin by connecting
the instrument to a signal conditioning circuit which indicates wind
direction value. This may be an indicator which displays wind direction
values in angular degrees or simply a voltmeter monitoring the output.
Hold or mount the instrument so the vane center of rotation is over
the center of a sheet of paper which has 30° or 45° crossmarkings.
Position the instrument so the mounting crossarm is oriented north-
south with the vane on the north and the anemometer on the south.
With the counterweight pointing directly at the anemometer the wind
direction signal should correspond to 180° or due south. Looking from
above, visually align the vane with each of the crossmarkings and
observe the indicator display. It should correspond to vane position
within 5°. If not, it may be necessary to adjust the relative position of
the vane skirt and shaft. See step 3 in the MAINTENANCE section
under potentiometer replacement.
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 352°. For example, in a circuit where 0 to
1.00 VDC represents 0° to 360°, the output must be adjusted for
0.978 VDC when the instrument is at 352° full scale. (352°/360° X
1.00 volts = 0.978 volts)
Wind speed calibration is determined by the cup wheel turning factor
and the output characteristics of the transducer. Calibration formulas
showing cup wheel rpm and frequency output vs. wind speed are
included below.
To calibrate wind system electronics using an actual signal from
the instrument, temporarily remove the cup wheel and connect an
Anemometer Drive to the cup wheel shaft. Calculate wind speed by
applying the appropriate calibration formula to the motor rpm and
adjust the signal conditioning electronics for proper value. For example,
with the cup wheel shaft turning at 1800 rpm, adjust the indicator to
display 22.7 meters per second. ([(0.01250 X 1800) + 0.2] = 22.7)
CALIBRATION FORMULAS
Model 03102 Wind Sentry Anemometer
WIND SPEED vs CUP WHEEL RPM
m/s = (0.01250 x rpm) + 0.2
knots = (0.02427 x rpm) + 0.4
mph = (0.02795 x rpm) + 0.4
km/hr = (0.04499 x rpm) + 0.7
WIND SPEED vs OUTPUT FREQUENCY - Hz
m/s = (0.7500 x Hz) + 0.2
knots = (1.4562 x Hz) + 0.4
mph = (1.6770 x Hz) + 0.4
km/hr = (2.6994 x Hz) + 0.7
MAINTENANCE
Given proper care, the Wind Sentry should provide years of service.
Because of its durable, corrosion resistant construction, the instrument
requires little maintenance. The only components likely to require
replacement due to normal wear are the precision ball bearings and
the azimuth potentiometer. Replacement of these components should
only be performed by a qualified instrument technician. If service
facilities are not available, return the instrument to the factory. Refer
to the accompanying drawings to become familiar with part names
and locations. Maximum torque on all set screws is 80 oz-in.
POTENTIOMETER REPLACEMENT
The potentiometer has a life expectancy of fifty million revolutions.
As it becomes worn, the element may produce noisy signals or
become non-linear. When the signal noise or non-linearity become
unacceptable, replace the potentiometer as follows:
1. REMOVE POTENTIOMETER
a) Remove three screws which secure upper and lower
sections of main housing.
b) Carefully remove upper housing exposing wiring connections
to circuit board.
c) Unsolder potentiometer wires from circuit board.
Note color coding.
d) Using a knife blade or similar instrument, loosen
potentiometer assembly from upper housing and slide it out.
2. INSTALL NEW POTENTIOMETER
a) Slide new potentiometer cell into upper housing. Be sure to
engage cell key into housing notch.
b) Solder potentiometer wires to circuit board.
Observe color code.
c) Join two sections of main housing. Secure with screws
removed in step 1a.