Campbell Scientific 03001-L User Manual

03001 R.M. Young Wind Sentry Set

03101 R.M. Young Wind Sentry Anemometer

03301 R.M. Young Wind Sentry Vane

Revision: 8/07

Copyright © 1986-2007

Campbell Scientific, Inc.

Warranty and Assistance

The 03001 R.M. YOUNG WIND SENTRY SET, 03101 R.M. YOUNG
WIND SENTRY ANEMOMETER, AND 03301 R.M. YOUNG WIND
SENTRY VANE are warranted by CAMPBELL SCIENTIFIC, INC. to be

free from defects in materials and workmanship under normal use and service
for twelve (12) months from date of shipment unless specified otherwise.
Batteries have no warranty. CAMPBELL SCIENTIFIC, INC.'s obligation
under this warranty is limited to repairing or replacing (at CAMPBELL
SCIENTIFIC, INC.'s option) defective products. The customer shall assume
all costs of removing, reinstalling, and shipping defective products to
CAMPBELL SCIENTIFIC, INC. CAMPBELL SCIENTIFIC, INC. will
return such products by surface carrier prepaid. This warranty shall not apply
to any CAMPBELL SCIENTIFIC, INC. products which have been subjected
to modification, misuse, neglect, accidents of nature, or shipping damage. This
warranty is in lieu of all other warranties, expressed or implied, including
warranties of merchantability or fitness for a particular purpose. CAMPBELL
SCIENTIFIC, INC. is not liable for special, indirect, incidental, or
consequential damages.

Products may not be returned without prior authorization. The following
contact information is for US and International customers residing in countries
served by Campbell Scientific, Inc. directly. Affiliate companies handle
repairs for customers within their territories. Please visit
www.campbellsci.com to determine which Campbell Scientific company
serves your country. To obtain a Returned Materials Authorization (RMA),
contact CAMPBELL SCIENTIFIC, INC., phone [phone]. After an
applications engineer determines the nature of the problem, an RMA number
will be issued. Please write this number clearly on the outside of the shipping
container. CAMPBELL SCIENTIFIC's shipping address is:

CAMPBELL SCIENTIFIC, INC.

RMA#_____
815 West 1800 North
Logan, Utah 84321-1784

CAMPBELL SCIENTIFIC, INC. does not accept collect calls.

R.M. Young Wind Sentry Table of
Contents

PDF viewers note: These page numbers refer to the printed version of this document. Use
the Adobe Acrobat® bookmarks tab for links to specific sections.

1. Introduction..................................................................1

2. Specifications ..............................................................2

3. Installation....................................................................3

3.1 Siting.........................................................................................................3

3.2 Assembly and Mounting...........................................................................3

3.3 03001 Wind Sentry Set.............................................................................3

3.4 03101 Anemometer ..................................................................................6

3.5 03301 Vane...............................................................................................6

4. Wiring............................................................................6

5. Example Programs......................................................7

5.1 Wind Speed ..............................................................................................7

5.2 Wind Direction.........................................................................................8

5.3 Wind Vector Processing Instruction.........................................................8

5.4 Example Programs....................................................................................8

5.4.1 CR1000 Example Program.............................................................9

5.4.2 CR10X Example Program ............................................................10

5.5 Long Lead Lengths.................................................................................11

6. Sensor Maintenance..................................................12

7. Troubleshooting ........................................................12

7.1 Wind Direction.......................................................................................12

7.2 Wind Speed ............................................................................................13

8. References .................................................................13

i

R.M. Young Wind Sentry Table of Contents

Appendices

A. Wind Direction Sensor Orientation........................A-1

A.1 Determining True North and Sensor Orientation................................A-1

B. Wind Direction Measurement Theory....................B-1

B.1 AC Half Bridge (P5) and BRHalf Instructions.................................... B-1

B.2 EX-DEL-SE (P4) Instruction .............................................................. B-1

Figures

3-1. 03001 Mounted to CM200 Series Crossarm with CM220..................... 4

3-2. 03001 Mounted to 019ALU or CM200 Series Crossarm

with PN 1049....................................................................................... 4

3-3. 03101 Anemometer Mounted to CM200 Series Crossarm

with CM220......................................................................................... 5

3-4. 03001 Mounted to CM100 Series Tripod Mast with CM216................. 5

A-1. Magnetic Declination for the Contiguous United States ...................A-2

A-2. Declination Angles East of True North are Subtracted from 0 to

Get True North................................................................................A-2

A-3. Declination Angles West of True North are Added to 0 to

Get True North................................................................................A-3

B-1. 03001/03301 Potentiometer in a Half Bridge Circuit........................ B-1

Tables

1-1. Recommended Lead Lengths ................................................................. 1

4-1. Connections to Campbell Scientific Dataloggers................................... 6

5-1. Wind Speed Multiplier ........................................................................... 7

5-2. Parameters for Wind Direction............................................................... 8

5-3. Wiring for Example Programs................................................................ 9

ii

R.M. Young Wind Sentry

1. Introduction

The 03001 Wind Sentry Set is used to measure horizontal wind speed and
direction.

Wind speed is measured with a three cup anemometer. Rotation of the cup
wheel produces an AC sine wave voltage with frequency proportional to wind
speed.

Vane position is transmitted by a 10K ohm potentiometer. With a precision
excitation voltage applied, the output voltage is proportional to wind direction.

The 03101 Anemometer and 03301 Vane can be ordered as separate sensors,
which are also covered in this manual. The R.M. Young Instruction Manual
includes additional information on the operating principles, installation and
maintenance of the sensor.

Lead length for the Wind Sentry is specified when the sensor is ordered.
Table 1-1 gives the recommended lead length for mounting the sensor at the
top of the tripod/tower with a 019ALU or CM200 series crossarm.

TABLE 1-1. Recommended Lead Lengths

CM6 CM10 CM110 CM115 CM120 UT10 UT20 UT30

12’ 15’ 15’ 20’ 25’ 15’ 25’ 38’

The 03001 Wind Sentry ships with:

(1) 03001 Wind Sentry including
03101 Anemometer
03301 Vane
crossarm
band clamp (P/N 4919)
(1) 10" x 3/4" unthreaded aluminium pipe (P/N 6332)
(1) Allen wrench (P/N 5201)

The 03101 Anemometer ships with:

(1) 03101 Anemometer
(1) 10" x 3/4" threaded galvanized pipe (P/N 12243)
(1) Allen wrench (P/N 5201)

1

R.M. Young Wind Sentry

The 03301 Vane ships with:

(1) 03301 Vane
(1) 10” x 3/4” threaded galvanized pipe (P/N 12243)
(1) Allen wrench (P/N 5201)

2. Specifications

Wind Speed (Anemometer) Specifications

Range: 0 to 50 m s-1 (112 mph), gust survival 60 m s-1 (134

Sensor: 12 cm diameter cup wheel assembly, 40 mm diameter

Accuracy: ±0.5 m s-1 (1.1 mph)
Turning Factor: 75 cm (2.5 ft)
Distance Constant
(63% recovery): 2.3 m (7.5 ft)
Threshold: 0.5 m s-1 (1.1 mph)
Transducer: Stationary coil, 1350 ohm nominal resistance
Transducer Output: AC sine wave signal induced by rotating magnet on cup

100 mV peak-to-peak at 60 rpm; 6 V peak-to-peak at

Output Frequency: 1 cycle per cup wheel revolution; 0.75 m s-1 per Hz
Cup Wheel Diameter: 12 cm (4.7 in)
Weight: 113 g (4 oz)

mph)

hemispherical cups

wheel shaft

3600 rpm

Wind Direction (Vane) Specifications

Range: 360° mechanical, 355° electrical (5° open)
Sensor: Balanced vane, 16 cm turning radius
Accuracy: ±5°
Damping Ratio: 0.2
Delay Distance
(50% recovery): 0.5 m (1.6 ft)
Threshold: 0.8 m s-1 (1.8 mph) at 10° displacement

1.8 m s-1 (4 mph) at 5° displacement
Transducer: Precision conductive plastic potentiometer; 10 K ohm

resistance; 0.5% linearity; life expectancy 20 million

revolutions.
Rated 1 watt at 40°C, 0 watts at 125°C.
Transducer Output: Analog dc voltage proportional to wind direction

angle with regulated excitation voltage supplied by

the datalogger
Vane Length: 22 cm (8.7 in)
Vane Weight: 170 g (6 oz)

Wind Sentry Assembly Specifications

Operating Temperature: -50° to +50°C assuming non-riming conditions
Overall Height: 32 cm (12.6 in)
Crossarm Length: 40 cm (15.7 in) between instruments (center-to-

center)
Mounting Diameter: 26.7 mm (1.05 in), mounts on standard 3/4 in. pipe

2

R.M. Young Wind Sentry

NOTE

3. Installation

3.1 Siting

3.2 Assembly and Mounting

The black outer jacket of the cable is Santoprene® rubber. This
compound was chosen for its resistance to temperature extremes,
moisture, and UV degradation. However, this jacket will
support combustion in air. It is rated as slow burning when
tested according to U.L. 94 H.B. and will pass FMVSS302.
Local fire codes may preclude its use inside buildings.

Locate wind sensors away from obstructions (e.g. trees and building). As a
general rule of thumb there should be a horizontal distance of at least ten times
the height of the obstruction between the windset and the obstruction. If it is
necessary to mount the sensors on the roof of a building, the height of the
sensors above the roof, should be at least 1.5 times the height of the building.
See Section 9 for a list of references that discuss siting wind speed and
direction sensors.

Tools Required:

• 5/64” Allen wrench

• Allen wrench provided with sensor

• 1/2” open end wrench

• compass and declination angle for the site (see Appendix A)

• small screw driver provided with datalogger

• UV resistant cable ties

• small pair of diagonal-cutting pliers

• 6 - 10” torpedo level

3.3 03001 Wind Sentry Set

Install the cupwheel to the anemometer shaft using the Allen wrench provided
with the sensor.

The 03001 mounts to a standard 0.75” IPS schedule 40 pipe (1.05” O.D.). A
12” long mounting pipe ships with the 03001 for attaching the sensor to a
019ALU or CM200 series crossarm with the CM220 or PN 1049 (Figures 3-1
and 3-2). The 03001 can also be mounted at the top of a CM6/CM10 tripod
mast, or to a CM110 series tripod with the CM216 as shown in Figure 3-4.

Mount the 019ALU or CM200 series crossarm to the tripod or tower. Orient
the crossarm North-South, with the 3/4” Nu-Rail or CM220 on the North end.
Appendix A contains detailed information on determining true north using a
compass and the magnetic declination for the site.

Secure the mounting pipe to the 019ALU or CM220. Place the 03001 on the
pipe, and orient the sensor crossarm North-South with the vane to the North.
Tighten the mounting post band clamp. Final sensor orientation is done after

3

R.M. Young Wind Sentry

the datalogger has been programmed to measure wind direction as described in
Appendix A.

Route the sensor cable along the underside of the crossarm to the tower/tripod
mast, and to the instrument enclosure. Secure the sensor cable to the crossarm
and mast using cable ties.

CM220

CM200 Series Crossarm

FIGURE 3-1. 03001 Mounted to CM200 Series Crossarm with CM220

PN 1049 Nu-Rail

CM200 Series Crossarm

4

FIGURE 3-2. 03001 Mounted to 019ALU or CM200 Series Crossarm

with PN 1049

R.M. Young Wind Sentry

CM220

CM200 Series Crossarm

FIGURE 3-3. 03101 Anemometer Mounted to CM200 Series Crossarm

with CM220

CM216

FIGURE 3-4. 03001 Mounted to CM100 Series Tripod Mast

with CM216

5

R.M. Young Wind Sentry

3.4 03101 Anemometer

3.5 03301 Vane

Install the cupwheel to the anemometer shaft using the Allen wrench provided
with the sensor.

The 03101 mounts to a threaded 0.75” IPS schedule 40 pipe (1.05” O.D.). A
10” long mounting pipe ships with the 03101 for attaching the sensor to a
019ALU or CM200 series crossarm with CM220 (Figures 3-3) or PN 1049.
The 03001 can also be mounted at the top of a CM6/CM10 tripod mast, or to a
CM110 series tripod with the CM216.

Mount the 019ALU or CM200 series crossarm to the tripod or tower. Screw
the mounting pipe into the base of the 03101, and attach the sensor / mounting
pipe to the crossarm.

Route the sensor cable along the underside of the crossarm to the tower/tripod
mast, and to the instrument enclosure. Secure the sensor cable to the crossarm
and mast using cable ties.

The 03301 Vane is typically ordered as a replacement vane for the 03001
Wind Sentry Set, and includes the bracket for attaching it to the 03001
crossarm. PN 4913 pipe mount (not included with the sensor) can be used to
attach the 03301 to a 019ALU or CM200 series crossarm (with the CM220 or
PN 1049), and the mounting pipe that ships with the sensor.

4. Wiring

Connections to Campbell Scientific dataloggers are given in Table 4-1. When
Short Cut for Windows software is used to create the datalogger program, the
sensor should be wired to the channels shown on the wiring diagram created
by Short Cut.

TABLE 4-1. Connections to Campbell Scientific Dataloggers

Color

Description

CR800
CR5000
CR3000
CR1000

CR510
CR500
CR10(X)

CR21X
CR7
CR23X

CR200

Black Wind Spd. Signal Pulse Pulse Pulse P_LL
White Wind Spd. Reference
Clear Wind Spd. Shield

G
G

Red Wind Dir. Signal SE Analog SE Analog SE Analog SE Analog
Black Wind Dir. Excitation Excitation Excitation Excitation Excitation
White Wind Dir. Reference
Clear Wind Dir. Shield

AG
G

6

R.M. Young Wind Sentry

Wind Speed Wind Direction

5. Example Programs

This section is for users who write their own programs. A datalogger program
to measure this sensor can be created using Campbell Scientifics’ Short Cut
Program Builder software. You do not need to read this section to use Short
Cut.

5.1 Wind Speed

Wind speed is measured with the Pulse Count instruction, and with the low
level AC configuration. For dataloggers programmed with Edlog, specify
configuration code 21 to output frequency in Hertz.

The expression for wind speed (U) is:
U = MX + B
where
M = multiplier

X = number of pulses per second (Hertz)
B = offset

Table 5-1 lists the multipliers (M) and offsets (Off) to obtain meters/second or
miles/hour when the Pulse Count instruction is configured to output the result
in Hz.

TABLE 5-1. Wind Speed Multiplier

(With Configuration Code 21*)

Model Meters/Second Miles/Hour

03001 / 03101 M = 0.750

Off = 0.2
*When configuration code 11 is used, the multiplier above is
divided by the execution interval in seconds.

M = 1.677
Off = 0.4

7

R.M. Young Wind Sentry

5.2 Wind Direction

The wind vane is coupled to a 10K potentiometer, which has a 5 degree
electrical dead band between 355 and 360 degrees.

The EX-DEL_SE measurement instruction (P4) is used for dataloggers that are
programmed with Edlog (e.g. CR10X, CR23X) and the CR200. The multiplier
to convert the measurement result (mV) to degrees is 355 deg/excitation mV.

The BRHalf measurement instruction is used for dataloggers that are
programmed with CRBasic (e.g. CR1000, CR3000). The multiplier to convert
the measurement result (mV/excitation mV) to degrees is 355.

Excitation voltages, range codes, and multipliers for CSI dataloggers are listed
in Table 5-2. Appendix B has additional information on the P4 and BRHalf
measurement instructions.

TABLE 5-2. Parameters for Wind Direction

CR10(X)

CR510
CR200

Measurement
Range

Excitation
Voltage

Multiplier 0.142 0.071 355 355
Offset 0 0 0 0

2500 mV,
slow

2500 mV 5000 mV 2500 mV 5000 mV

CR7
21X
CR23X

5000 mV,
slow/60 Hz

5.3 Wind Vector Processing Instruction

The Wind Vector output instruction is used to process and store mean wind
speed, unit vector mean wind direction, and Standard Deviation of the wind
direction (optional) from the measured wind speed and direction values.

5.4 Example Programs

The following programs measure the 03001 every 5 seconds, and store mean
wind speed, unit vector mean direction, and standard deviation of the direction
every 60 minutes. Wiring for the examples is given in Table 5-3.

CR800
CR1000

2500 mV,
60 Hz,
reverse
excitation

CR5000
CR3000

5000 mV,
60 Hz,
reverse
excitation

8

R.M. Young Wind Sentry

TABLE 5-3. Wiring for Example Programs

Color Description CR1000 CR10X

Black Wind Spd. Signal P1 P1
White Wind Spd. Reference
Clear Wind Spd. Shield

G
G

Red Wind Dir. Signal SE 1 SE 1
Black Wind Dir. Excitation EX 1 E1
White Wind Dir. Reference
Clear Wind Dir. Shield

AG
G

5.4.1 CR1000 Example Program

'CR1000
'Declare Variables and Units

Public Batt_Volt
Public WS_ms
Public WindDir

Units Batt_Volt=Volts
Units WS_ms=meters/second
Units WindDir=Degrees

'Define Data Tables

DataTable(Table1,True,-1)
DataInterval(0,60,Min,10)
WindVector (1,WS_ms,WindDir,FP2,False,0,0,0)
FieldNames("WS_ms_S_WVT,WindDir_D1_WVT,WindDir_SD1_WVT")
EndTable

'Main Program

BeginProg
Scan(5,Sec,1,0)

'Default Datalogger Battery Voltage measurement Batt_Volt:

Battery(Batt_Volt)

'03001 or 03101 RM Young Wind Sentry Wind Speed Sensor measurement - WS_ms:

PulseCount(WS_ms,1,1,1,1,0.75,0.2)
If WS_ms<0.21 Then WS_ms=0

'03001 or 03301 RM Young Wind Sentry Wind Direction Sensor measurement - WindDir:

BrHalf(WindDir,1,mV2500,1,1,1,2500,True,0,_60Hz,355,0)

'Use mV5000 range and 5000 mV excitation for CR3000 and CR5000 dataloggers.

If WindDir>=360 OR WindDir<0 Then WindDir=0

9

R.M. Young Wind Sentry

'Call Data Tables and Store Data

CallTable(Table1)
NextScan
EndProg

5.4.2 CR10X Example Program

;{CR10X}

*Table 1 Program
01: 5.0000 Execution Interval (seconds)

1: Batt Voltage (P10)
1: 1 Loc [ Batt_Volt ]

;03001 or 03101 RM Young Wind Sentry Wind Speed Sensor measurement - WS_ms:

2: Pulse (P3)
1: 1 Reps
2: 1 Pulse Channel 1
3: 21 Low Level AC, Output Hz
4: 2 Loc [ WS_ms ]
5: 0.75 Multiplier
6: 0.2 Offset

3: If (X<=>F) (P89)
1: 2 X Loc [ WS_ms ]
2: 4 <
3: 0.21 F
4: 30 Then Do

4: Z=F x 10^n (P30)
1: 0 F
2: 0 n, Exponent of 10
3: 2 Z Loc [ WS_ms ]

5: End (P95)

;03001 or 03301 RM Young Wind Direction Sensor measurement - WindDir:

6: Excite-Delay (SE) (P4)
1: 1 Reps
2: 5 2500 mV Slow Range ;5000 mV(slow/60hz) range for CR23X, 21X, or CR7
3: 1 SE Channel
4: 1 Excite all reps w/Exchan 1
5: 2 Delay (0.01 sec units)
6: 2500 mV Excitation ;5000 mV for CR23X, 21X, or CR7
7: 3 Loc [ WindDir ]
8: 0.142 Multiplier ;0.071 for CR23X, 21X, or CR7
9: 0 Offset

10

7: If (X<=>F) (P89)
1: 3 X Loc [ WindDir ]
2: 3 >=
3: 360 F
4: 30 Then Do

8: Z=F x 10^n (P30)
1: 0 F
2: 0 n, Exponent of 10
3: 3 Z Loc [ WindDir ]

9: End (P95)

10: If (X<=>F) (P89)
1: 3 X Loc [ WindDir ]
2: 4 <
3: 0 F
4: 3 Then Do

11: Z=F x 10^n (P30)
1: 0 F
2: 0 n, Exponent of 10
3: 3 Z Loc [ WindDir ]

12: End (P95)

13: If time is (P92)
1: 0 Minutes (Seconds --) into a
2: 60 Interval (same units as above)
3: 10 Set Output Flag High (Flag 0)

14: Set Active Storage Area (P80)^15464
1: 1 Final Storage Area 1
2: 101 Array ID

15: Real Time (P77)^6687
1: 1220 Year,Day,Hour/Minute (midnight = 2400)

16: Wind Vector (P69)^28601
1: 1 Reps
2: 0 Samples per Sub-Interval
3: 0 S, theta(1), sigma(theta(1)) with polar sensor
4: 2 Wind Speed/East Loc [ WS_ms ]
5: 3 Wind Direction/North Loc [ WindDir ]

R.M. Young Wind Sentry

5.5 Long Lead Lengths

When sensor lead length exceeds 100 feet, the settling time allowed for the
measurement of the vane should be increased to 20 milliseconds.

11

R.M. Young Wind Sentry

For dataloggers programmed with Edlog (and the CR200), the EX-DEL-SE
(P4) measurement instruction should be used. Enter a 2 in the P4 “Delay”
parameter for a 20 millisecond delay.

For dataloggers programmed with CRBasic, increase the “Settling Time”
parameter of the BRHalf instruction to 20 milliseconds (20,000 microseconds).

CAUTION

The 60 Hz rejection option can not be used with the DC
Half Bridge instruction, when the delay is not zero. Do not
use long lead lengths in electrically noisy environments.

6. Sensor Maintenance

Every month do a visual/audio inspection of the anemometer at low wind
speeds. Verify that the cup assembly and wind vane rotate freely. Inspect the
sensor for physical damage.

Replace the anemometer bearings when they become noisy, or the wind speed
threshold increases above an acceptable level. The condition of the bearings
can be checked with a paper clip as described in the R.M. Young manual.

The potentiometer has a life expectancy of fifty million revolutions. As it
becomes worn, the element can produce noisy signals or become non-linear.
Replace the potentiometer when the noise or non-linearity becomes
unacceptable.

Contact Campbell Scientific for a Return Materials Authorization (RMA)
number at [phone].

7. Troubleshooting

12

7.1 Wind Direction

Symptom: -9999 or no change in direction

1. Check that the sensor is wired to the Excitation and Single-Ended channel
specified by the measurement instruction.

2. Verify that the excitation vo ltage and Range code are correct for the
datalogger type.

3. Disconnect the sensor from the datalogger and use an ohm meter to check
the potentiometer. Resistance should be about 10K ohms between the
black and white wires. The resistance between either the black/red or
white/red wires should vary from 1K to 11K depending on vane position.
Resistance when the vane is in the 5 degree dead band should be about
1M ohm.

7.2 Wind Speed

R.M. Young Wind Sentry

Symptom: Incorrect wind direction

1. Verify that the Excitation voltag e, Range code, multiplier and offset
parameters are correct for the datalogger type.

2. Check orientation of sensor as described in Section 3.

Symptom: No wind speed

1. Check that the sensor is wired to the Pulse channel specified by the Pulse
count instruction.

2. Disconnect the sensor from the datalogger and use an ohm meter to check
the coil. The resistance between the white and black wires should be a
nominal 1350 ohms. Infinite resistance indicates an open coil; low
resistance indicates a shorted coil.

3. Verify that the Configuration Code, and Multiplier and Offset parameters
for the Pulse Count instruction are correct for the datalogger type.

8. References

Symptom: Wind speed does not change

1. For the dataloggers that are programmed with Edlog, the input location
for wind speed is not updated if the datalogger is getting “Program Table
Overruns”. Increase the execution interval (scan rate) to prevent
overruns.

The following references give detailed information on siting wind speed and
wind direction sensors.

EPA, 1989: Quality Assurance Handbook for Air Pollution Measurements
System, Office of Research and Development, Research Triangle Park, NC,

27711.

EPA, 1987: On-Site Meteorological Program Guidance for Regulatory
Modeling Applications, EPA-450/4-87-013, Office of Air Quality Planning
and Standards, Research Triangle Park, NC 27711.

The State Climatologist, 1985: Publication of the American Association of
State Climatologists: Height and Exposure Standards, for Sensors on
Automated Weather Stations, vol. 9, No. 4.

WMO, 1983: Guide to Meteorological Instruments and Methods of
Observation, World Meteorological Organization, No. 8, 5th edition, Geneva,
Switzerland.

13

R.M. Young Wind Sentry

This is a blank page.

14

Appendix A. Wind Direction Sensor Orientation

A.1 Determining True North and Sensor Orientation

Orientation of the wind direction sensor is done after the datalogger has been
programmed, and the location of True North has been determined. True North is
usually found by reading a magnetic compass and applying the correction for
magnetic declination; where magnetic declination is the number of degrees
between True North and Magnetic North. Magnetic declination for a specific site
can be obtained from a USGS map, local airport, or through a computer service
offered by the USGS at www.ngdc.noaa.gov/seg/geomag/. A general map
showing magnetic declination for the contiguous United States is shown in Figure
A-1.

Declination angles east of True North are considered negative, and are subtracted
from 0 degrees to get True North as shown Figure A-2. Declination angles west
of True North are considered positive, and are added to 0 degrees to get True
North as shown in Figure A-3. For example, the declination for Logan, Utah is
14° East. True North is 360° - 14°, or 346° as read on a compass.

Orientation is most easily done with two people, one to aim and adjust the
sensor, while the other observes the wind direction displayed by the
datalogger.

1. Establish a reference point on the horizon for True North.

2. Sighting down the instrument center line, aim the nose cone, or
counterweight at True North. Display the input location or variable for wind
direction using a hand-held keyboard display, PC, or palm.

3. Loosen the u-bolt on the CM220 or the set screws on the Nu-Rail that secure
the base of the sensor to the crossarm. While holding the vane position,
slowly rotate the sensor base until the datalogger indicates 0 degrees.
Tighten the set screws.

A-1

Appendix A. Wind Direction Sensor Orientation

Subtract declination from 360° Add declination to 0°

20 W

18 W

16 W

14 W

12 W

10 W

8 W

6 W

4 W

20 E

18 E

22 E

16 E

14 E

12 E

10 E

8 E

6 E

4 E

2 E

2 W

0

FIGURE A-1. Magnetic Declination for the Contiguous United States

A-2

FIGURE A-2. Declination Angles East of True North Are Subtracted

From 0 to Get True North

Appendix A. Wind Direction Sensor Orientation

FIGURE A-3. Declination Angles West of True North Are Added to 0 to

Get True North

A-3

Appendix A. Wind Direction Sensor Orientation

This is a blank page.

A-4

Appendix B. Wind Direction

A

(

+

=

(

+⋅=

Measurement Theory

It is not necessary to understand the concepts in this section for the general
operation of the 03001 with Campbell Scientific’s datalogger.

Rt

Rs

FIGURE B-1. 03001 / 03301 Potentiometer in a Half Bridge Circuit

B.1 BRHalf Instruction

The BRHalf instruction outputs a precise excitation voltage (Vx), and measures
the voltage between the wiper and ground (V
wiper and ground, R
result is the ratio of the measured voltage to the excitation voltage (V
ratio is related to the resistance as shown below:

The maximum value that R
west side of north to the east side of north (at this point R
its maximum value of 1.0 mV/mV at 355 degrees. The multiplier to convert

to degrees is 355 degrees / 1.0 Vs/Vx = 355. Since the datalogger outputs

V

s/Vx

the ratio V
even though they use a different excitation voltage. See Section 13.5 in the
datalogger manual from more information on the b rid ge measurements.

s / Vx

EXCITATION VOLTAGE (Vx)

SIGNAL + (Vs)

ZIMUTH REFERENCE

EARTH GROUND CONNECT N

). The resistance between the

s

, and Vs varies with wind direction. The measurement

s

)

RRRVV

stsxs

will reach is Rf, just before it crosses over from the

s

= 0). Vs / Vx reaches

t

, the multiplier is the same for both the CR10(X) and CR3000,

s/Vx

IO

). This

B.2 EX-DEL-SE (P4) Instruction

Instruction 4 outputs a precise excitation voltage (Vx) and measures the voltage
between the wiper and analog ground, V
and analog ground, R
the measured voltage, V
shown below:

The maximum value that R
west side of north to the east side of north (at this point R
maximum value of V

, and Vs varies with wind direction. Instruction 4 outputs

s

. This measured voltage is related to resistance as

s

)

RRRVV

stsxs

will reach is Rf just before it crosses over from the

s

. This maximum voltage equals 2500 mV for an

x

. The resistance between the wiper

s

= 0). Vs reaches its

t

B-1

Appendix B. Wind Direction Measurement Theory

excitation voltage of 2500 mV recommended for the CR10( X) and 5000 mV
for an excitation voltage of 5000 mV recommended for the CR23X at 355
degrees. The multiplier to convert V

0.142 for the CR10X, or, 355 degrees / 5000 mV = 0.071 for the CR23X. See
Section 13.5 in the datalogger manual from more information on the bridge
measurements

to degrees is 355 degrees / 2500 mV =

s

B-2

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