Met One Instruments 020C User manual

MODEL 020C
WIND DIRECTION SENSOR
OPERATION MANUAL
Document No 020C-9800

020C-9800 REV A Page 1
020C WIND DIRECTION SENSOR
OPERATION MANUAL
1.0 GENERAL INFORMATION
1.1 The Model 020C Wind Direction Sensor uses a lightweight, vane and a micro torque
potentiometer to produce an analog voltage output proportional to wind direction. An
internal heater reduces moisture for extended bearing life. The sensor mounts in a
crossarm assembly, such as the Met One Instruments’ Model 191-1.
1.2 The sensor cable has a quick-connect connector with vinyl-jacketed, shielded cable.
Cable length is given in-XX feet on each cable part number. A 1957-XX cable is
supplied for translators and data loggers having terminal strip connections. (Color
code, Figure 2-1).
Table 1-1
Model 020C Wind Direction Sensor Specifications
Performance
Azimuth Electrical 0-356q
Mechanical 0-360q
Threshold 0.6 mph
Linearity r½% of full scale
Accuracy r3q
Damping Ratio 0.4
Delay Distance Less than 3 feet
Temperature Range -50qC to +85qC
Electrical Characteristics
Input Power 12V DC, 10 mA
Output* a. 0-5 volts for 0-360q
b. 0-2.5 volts for 0-360q
c. 0-1.0 volts for 0-360q
*NOTE: Items A and B are customer selectable. Item C is optional.

020C-9800 REV A Page 2
Output Impedance 100 Ohms maximum
Maximum Cable Length 300 feet maximum (consult factory for special
cable requirements)
Physical Characteristics
Weight 1.1 pounds
Finish Anodized Aluminum
Mounting Use with Crossarm Model 191 or equivalent
Cabling 1957-XX Cable (XX is cable length in feet)
Optional Accessories
A. External heater assembly and power supply for extreme low temperature
operation.
B. Aluminum vane assembly.
C. Model 040 Degree Wheel Calibrator.
D. Model 042 Telescopic Orientation Fixture.
2.0 INSTALLATION
2.1 Model 020C Wind direction Sensor Installation
A. Select output voltage range. Slide outer cover down to expose circuit board.
Jumper E1 (at top of 2840 board) should be in 5v position for 0-5v output, or 2.5v
position for 0-2.5v output.
B. Check to see that the vane assembly rotates freely.
C. Makes sure that the vane assembly is properly balanced and that the balance
counterweight is tight. With the vane mounted, hold the sensor horizontal. Verify
balance.
D. Install the sensor in the crossarm with the keyed bushing. The orientation screw
in the stem of the wind direction sensor will fit through the hole in the mounting
bushing.
E. Connect the cable assembly to the keyed sensor receptacle and secure it to the
mounting arm using cable ties.
2.2 Model 020 Wind Direction Sensor Alignment

020C-9800 REV A Page 3
(Refer to Figure 2-1 “Typical 020C Installation”). The Orientation screw located on
the stem of the sensor is to be oriented so that it points south. Proceed as follows:
A. Tape the sensor hub and column together so that the notches on each part are
exactly aligned.
B. Loosen the two set screws in the alignment bushing so that the sensor and
bushing may be rotated.
C. Rotate the sensor so that vane (counterweight end) points directly south.
D. A transit located either directly south or directly north will facilitate the alignment
process; merely rotate sensor until vane and sensor column merge completely,
then tighten the set screws into the mounting bushing.
E. Optional alignment accessories are available:
1. A telescopic orientation device, which is inserted into alignment bushing
until alignment is achieved. Bushing is locked and orientation device is
removed and wind direction sensor installed.
2. A compass orientation device operates in similar manner, but is not
suitable for steel towers or poles.
2.3 Wiring
The cable assembly contains five wires. Typical wiring hookup is shown in Figure 2-1.
2.4 Lightning Protection
Weather sensors are sensitive to direct or nearby lightning strikes. A well-grounded
metal rod or frame should be placed above the sensor installation. In addition, the
shield on the signal cable (white/brown wire) must be connected to a good earth
ground at the translator end, and the cable route should not be vulnerable to
lightning.

020C-9800 REV A Page 4

020C-9800 REV A Page 5
3.0 OPERATIONAL CHECK-OUT
3.1 020C Wind Direction Sensor Check-Out (standard 360qoperation)
A. With the sensor connected to the input, upon movement of the sensor’s vane in a
clockwise direction (as seen from above), the module’s output will move up-
scale. Movement of the module’s output will progress up-scale until the 360q(full
scale) mark has been reached; then output will drop to 0q. When the notches on
the rotating hub and the column of the sensor are exactly aligned, the output
signal will correspond to 180q.
3.2 020C Wind Direction Sensor Check-Out (with 540qconversion electronics)
A. With the sensor connected to the input, upon movement of the sensor’s vane in a
clockwise direction (as seen from above), the module’s output will move up-
scale. Movement of the module’s output will progress up-scale until the 540q(full
scale) mark has been reached, and then the output will drop to 180q. Continued
clockwise rotation will again bring the module’s output up-scale to 540qand the
action is repeated. When the notches on the rotating hub and the column of the
sensor are exactly aligned, the output signal will correspond to 180q(or 540qon
the expanded scale.
3.3 If the sensor heater is used, then check internal heater operation by sliding sensor
cover down and touching the housing behind the printed circuit board. The housing
should feet warmer than the adjoining metal parts. The sensor has a built-in heater
that is designed to provide a raise in the internal temperature, providing a small
positive pressure. This heater requires an external 12V (@ 350 ma) power supply.
4.0 MAINTENANCE AND TROUBLESHOOTING
4.1 General Maintenance Schedule
6-12 Month Intervals:
A. Inspect Sensor for proper operation per Section 3.1 or 3.2.
B. Calibration as required per Section 4.4.
12-24 Month Intervals:
A. Replacement of sensor bearings as per Section 4.5.
B. Replacement of potentiometer as per Section 4.6
Table 4-1
020C Wind Direction Sensor Troubleshooting

020C-9800 REV A Page 6
Symptom Probable Cause Solution Refer to
No wind direction
output
Loss of supply
voltage
Check translator
+12V supply and
connecting cables
Figure 2-1
Faulty integrated
circuit amplifier
(output often will be
steady 5.0V)
Replace IC amplifier
(Plug-in)
Section 4.8
Faulty potentiometer Replace
potentiometer
Section 4.6
No change in
wind direction
output below 2-5
mph
Bad bearings Replace bearings Section 4.5
4.2 020C Wind Direction Sensor: 6-12 Month Periodic Service (Refer to Assembly
Drawing)
A. At the crossarm assembly, disconnect the quick disconnect plug from the sensor
(leave the cable secured to the crossarm). Remove the sensor from the
crossarm assembly bushing. Leave the bushing secure in the fitting.
B. Loosen the set screw on the bottom edge of the vane hub. Support the rotating
hub of the sensor with one hand and pull the vane assembly free.
C. Visually inspect the wind vane assembly to ensure that the wind vane and
counterweight are securely attached to the wind vane rod, and that the set screw
in the top edge of the rotating hub holds the rod in place.
D. Slide the sensor cover down to expose the potentiometer assembly and signal
conditioning module.
E. Inspect the interior of the sensor for any signs of corrosion.
F. Inspect the potentiometer for loose wires, cracks, and corrosion.
G. Inspect the shaft coupler for proper position. Make sure that the marks on the
rotating hub and the column assembly are aligned, and that all special set screws
are tight.
H. Inspect the circuit board assembly for cracks and corrosion. See Section 4.6 B.

020C-9800 REV A Page 7
I. Rotate the sensor hub assembly to make sure that it turns freely, and that the
sensor bearings are not damaged.
J. Make sure that the potentiometer assembly is rigid in its holder.
K. Apply a small amount of silicone lubricant (Dow Corning DC-33 or equivalent) to
the sensor O-ring seals. Slide the cover up over the sensor and wipe off any
excess lubricant.
L. Support the rotating hub of the sensor with one hand and mount the wind vane
assembly on the hub. The wind vane assembly is keyed to fit the pin on the hub.
Tighten the set screw in the bottom edge of the vane hub.
M. A moisture vent is located on the base of the sensor. Make sure that this vent is
clear.
N. Reinstall sensor according to installation procedure (Section 2.1); verify proper
operation using procedures in Section 3.1 and 3.2.
4.3 020C Wind direction Sensor Maintenance (Refer to 020C drawing for assembly
information)
The following procedures require a relatively clean, dry work area, a source of 12
VDC power at approximately 20 mA, a Model 040 Degree Wheel, and a 4-1/2 digit or
better digital voltmeter.
4.4 020C Wind Sensor Calibration
Any time the bearing, shaft, hub or potentiometer is removed and replaced, the
alignment of the potentiometer must be reestablished. Perform the following steps
for calibration:
A. Connect the sensor to a 12-volt power supply:
Pin A +12V
Pin B Common
B. Connect digital voltmeter positive lead to Terminal 3 of potentiometer; set jumper
E1 to 5V position; adjust R7 on the circuit board assembly for a reading of
5.000V.
C. Set jumper E1 to 2.5V position. Adjust R6 on the circuit board assembly for a
reading of 2.500V.
D. Connect a high impedance digital (4-1/2 digit or better, see above) voltmeter
between common and Pin C (signal output).

020C-9800 REV A Page 8
E. Slide the Model 040 Degree Wheel onto the column of the wind direction sensor.
Install the 040 Pointer Assembly onto the rotating hub. Tape sensor hub and
column together so that the notches on both parts are exactly aligned.
F. Slide the degree wheel up to the pointer, allowing clearance space, and rotate
the degree wheel until the pointer is at exactly 180qon the wheel. Tighten the
degree wheel to the column, checking to ensure that it does not interfere with the
rotation of the pointer.
G. Remove tape and rotate the pointer, then recheck the alignment of the two
notches with the 180qmark on the degree wheel. Readjust if necessary.
H. Loosen the set screws in the drive coupler (#21).
I. Place the pointer at 180qand rotate the potentiometer drive coupler so that an
output of 2.500 r0.005V (1.250V with a 2.5V output range) is measured. Tighten
set screws in the drive coupler (#21) and recheck at 180q. Readjust if necessary.
J. Reconnect digital voltmeter to Pin C of the sensor connector and rotate the
pointer to 180q. The output reading should be 2.500V r40mV (1.25V r20mV with
2.5V output range).
K. Remove 040 Degree Wheel and pointer. This completes the alignment
procedure.
4.5 Sensor Bearing Replacement (Refer to 020C Sensor Assembly drawing)
A. Remove sensor from tower and remove vane assembly. Refer to Section 4.2.
B. Disassemble sensor and remove old bearing. (#6)(Refer to Assembly Drawing)
1. Slide the sensor cover (18) down to expose the potentiometer assembly
(23) and circuit board assembly (15).
2. Make sure that the two (lower) special set screws on the COUPLER (21)
next to the potentiometer are tight, and then loosen the two (upper)
special set screws.
NOTE: Any time the shaft coupler assembly is removed, the
potentiometer alignment procedures outlined in Section 4.3 must be
performed.
3. Slowly pull the rotating hub/shaft assembly (7) out of the column (8).
4. Remove the shield (4) and slinger (5) from the column.

020C-9800 REV A Page 9
5. Insert a right-angle type of tool, such as an Allen wrench, into the bearing;
cock it slightly to one side and remove the bearing (6).
6. Clean dirt from bearing bore, using a cotton swab and alcohol.
C. Install the new bearing and assemble the sensor.
1. Install new upper bearing in the column assembly. Bearing should slide
easily into bearing bore.
CAUTION: Do not lubricate bearing. Do not force.
2. Install slinger (4) and shield (5) on the column (8).
3. Insert the rotating hub/shaft assembly (7) into the column (8), through the
shield (4), slinger (5), and bearing (6).
4. Support the drive coupler (21) with one hand and slowly push the rotating
hub/shaft assembly (7) into it until the shaft bottoms.
D. Recalibrate sensor in accordance with Section 4.3.
E. Replace vane assembly and reinstall (refer to Section 2.1).
4.6 Potentiometer Replacement (Refer to 020C Sensor Assembly drawing)
A. Remove sensor from tower and vane assembly. Refer to Section 4.2.
B. Disassemble sensor:
1. Slide the sensor cover (18) down to expose the potentiometer assembly
(23) and circuit board assembly (15). Unsolder three wires to
potentiometer (note color code for reinstallation).
2. Loosen the two set screws in coupler holding potentiometer.
3. Remove the three recessed Phillips head screws from the top housing
and remove the column and pot assembly.
4. Remove three screws (22) to separate potentiometer from column.
C. Install New Potentiometer by following above instructions in reverse order.
D. Recalibrate sensor as per Section 4.4.
E. Replace vane assembly and reinstall (refer to Section 2.1).

020C-9800 REV A Page 10
4.7 2840 Circuit Board Assembly replacement. (Refer to 020C Assembly drawing)
A. Remove sensor from tower and remove vane assembly (refer to Section 4.2).
B. Slide the sensor cover down to expose the sensor interior.
C. Remove two screws (14) holding circuit board assembly (15). Note color of
wires.
D. Unsolder three wires to potentiometer assembly from circuit board (15) and note
color and position of wires.
E. Unsolder three wires to connector from circuit board (15). Note color and position
of wires.
F. Install new circuit board assembly by reversing above procedure.
G. Adjust potentiometer R7 or R6 according to procedure of Section 4.5.
H. Replace vane assembly and reinstall (refer to Section 2.1).
4.8 Integrated Amplifier Replacement
A. Remove sensor from tower and vane assembly (refer to Section 4.2).
B. Slide the Sensor Cover (18) down to expose the sensor interior.
C. Carefully pry amplifier from its socket on the circuit board noting Pin 1 orientation.
D. Install replacement integrated amplifier by reversing above procedures.
E. Recalibrate sensor per Section 4.4.
4.9 020C Wind Direction Sensor Repair and Recalibration Service
The factory provides fast, economical service for the user. This repair and
calibration service includes disassembly and detailed inspection of all moving
mechanical parts and electronic components.
Service includes replacement of bearings, regardless of apparent condition,
calibration, and functional test of sensor. Replacement of the following items, if
necessary, is also included: O-rings, shield and slinger, shaft, set screws. Charges
for any additional materials will be added to the basic service charge.

020C-9800 REV A Page 11
Table 4-2
020C Replaceable Parts List
ITEM # PART # DESCRIPTION
1 10296 Magnesium Vane Assembly, or
2755 Alum Vane Assembly
4 1009 Shield
5 1010 Slinger
6 1055 Bearing
7 2658 Hub/Shaft Assembly
9 720120 O-ring
10 805080 Resister 5W, 35:
12 480100 Cable Clamp
13 860050 Standoff
14 601240 Screw, PH 4-40x1/4
15 2840-1 PCBA Assembly
18 2675 Cover
21 2727 Coupler, Direct
22 601070 Screw PH 2-56 x 1/8
23 2017 Potentiometer Assembly
27 601330 Screw, FH 82q4-40 x 3/8
28 600400 Nut, Hex, Kep 4-40
29 601850 Screw, Soc. Hd Cap 10-32x5/8
30 601240 Screw, FH 82q4-40x1/4
31 601251 Set Screw 4-40x1/8

020C-9800 REV A Page 12

020C-9800 REV A Page 13