Campbell 024A Instruction Manual

Model 024A Met One

Wind Direction Sensor

Revision: 6/10

Copyright © 1989-2010

Campbell Scientific, Inc.

Warranty and Assistance

The 024A MET-ONE WIND DIRECTION SENSOR is 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

For all returns, the customer must fill out a “Declaration of Hazardous Material
and Decontamination” form and comply with the requirements specified in it.
The form is available from our website at
completed form must be either emailed to [e-mail]
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www.campbellsci.com/repair

. A

or faxed to

024A 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. Function........................................................................1

2. Specifications ..............................................................1

3. Installation....................................................................2

3.1 Siting.........................................................................................................2

3.2 Assembly and Mounting...........................................................................2

4. Wiring............................................................................3

5. Programming ...............................................................3

5.1 Datalogger Instruction..............................................................................3

5.2 Calibration and Orientation ......................................................................4

5.3 Example Programs....................................................................................5

6. General Maintenance Schedule..................................8

6.1 6 to 12 Month Periodic Service *.............................................................8

6.2 24 to 36 Month Service * .........................................................................8

7. References .................................................................11

Appendix

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

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

Figures

3-1. Bushing Installation on 024A Sensor......................................................2

3-2. Schematic of 024A Wind Direction Sensor ............................................3

6-1. Cable Diagram.........................................................................................8

6-2. Parts Diagram..........................................................................................9

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

i

024A Table of Contents

Tables

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

4-1. Connections to Campbell Scientific Dataloggers................................... 3

5-1. Parameters for Wind Direction............................................................... 4

6-1. Met-One Parts List Reproduced by Campbell Scientific, Inc............... 10

ii

024A Met-One Wind Direction Sensor

1. Function

The Met-One 024A Wind Vane measures wind direction from 0 to 360 degrees
with a 5 degree accuracy specification. The 024A utilizes a potentiometer to
vary the sensor resistance in relation to wind direction.

Lead length for the 024A is specified when the sensor is ordered. Table 1-1
gives the recommended lead length for mounting the sensor at the top of a
tripod/tower via a CM202 or 019ALU crossarm.

TABLE 1-1. Recommended Lead Lengths

CM6 CM10 CM110 CM115 CM120 UT10 UT20 UT30

11’ 14’ 14’ 19’ 24’ 14’ 24’ 37’

2. Specifications

Range 0 to 360 degrees

Threshold 0.447 m/s (1.0 mph)

Accuracy ±5 degrees

Temperature Range -50°C to +70°C

Delay Distance Less than 1.5 m (5 ft.)

Damping Ratio
Standard 0.25
Optional 0.4

Potentiometer Specifications
Sand, Dust, and Fungus MIL-E-5272
Salt Spray MIL-E-12934
Resistance 0-10,000 Ohms

Weight 450 g (1 lb.)

Dimensions
Overall height 13.3” (33.8 cm)
Overall length 17.6” (44.7 cm)
Tail height 12” (30.5 cm)
Tail Width 3” (7.6 cm)

1

024A Met-One Wind Direction Sensor

3. Installation

3.1 Siting

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 7 for a list of references that discuss siting wind direction sensors.

3.2 Assembly and Mounting

Remove the Allen hex screw in the lower part of the sensor housing and insert
the 024A in the mounting bushing (see Figure 3-1). Tighten the screw in the
bushing onto the sensor housing.

Mount the crossarm to the tripod or tower. Orient the crossarm North-South,
with the CM220 mount or 17953 1” x 1” NU-RAIL fitting on the North end.
Insert the sensor in the CM220 or NU-RAIL fitting. Align the sensor so that
the counter weight points to true South and tighten the u-bolts on the CM220
or tighten the set screws on the NU-RAIL fitting.

NOTE

Appendix A contains detailed information on determining and
using a compass and the magnetic declination for the site.

Connect the cable assembly to the sensor receptacle.

2

FIGURE 3-1. Bushing Installation on 024A Sensor

4. Wiring

024A Met-One Wind Direction Sensor

FIGURE 4-1. Schematic of 024A Wind Direction Sensor

Figure 4-1, Figure 6-1, and Table 4-1 shows wiring. 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.

Color

Description

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

5. Programming

NOTE

5.1 Datalogger Instruction

TABLE 4-1. Connections to Campbell Scientific Dataloggers

CR800
CR5000
CR3000
CR1000

CR510
CR500
CR10(X)

AG
G

21X
CR7
CR23X

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.

CR200(X)

The datalogger instruction that measures the 024A is datalogger dependent.
The BRHalf measurement instruction is used for our CR800, CR850, CR1000,
CR3000, and CR5000 dataloggers. Our CR200(X)-series dataloggers use the
EX-DEL_SE. Our Edlog dataloggers (e.g., CR510, CR10(X), CR23X) use

3

024A Met-One Wind Direction Sensor

Instruction 4 – Excite, Delay, Measure. Excitation voltages, range codes, and
delays for CSI dataloggers are listed in Table 5-1. The process for determining
the correct multiplier is provided in Section 5.2.

TABLE 5-1. Parameters for Wind Direction

Measurement
Range

Excitation
Voltage

Delay or Settling
Time

Multiplier See Section

Offset 0 0 0 0 0

CR200(X)
2500 mV 250 mV, fast 500 mV, fast 2500 mV,

2500 mV 500 mV 1000 mV 2500 mV 5000 mV

2 ms 2 ms 2 ms 2 ms 2 ms

5.2

CR10(X),
CR510

See Section 5.2 See Section

CR7, 21X,
CR23X

5.2

CR800, CR850,
CR1000

250 microsecond
integration,
reverse excitation

See Section 5.2 See Section 5.2

CR5000,
CR3000

5000 mV,
250 microsecond
integration, reverse
excitation

5.2 Calibration and Orientation

Conversion of the voltage output into wind direction is done by entering the
proper multiplier. The proper multiplier is calculated by dividing 360 by the
full scale input voltage (i.e., 360/FSIV). The full scale input voltage (FSIV) is
the maximum voltage output from the wind vane. This is found by creating a
datalogger program with a multiplier of 1, the default excitation, and a fast
scan interval. With a multiplier of 1, the value stored in the variable or input
location is simply the voltage output. Slowly turn the wind vane; the shoulder
screw must first be removed. The maximum value observed is the full scale
input voltage (FSIV).

4

NOTE

If the reading is -99999, exceeds 500 on the 21X or CR7, or
exceeds 250 on the CR10, then reduce the millivolts of
excitation by 5 mV.

Multiplier 360/FSIV*
Offset 0.0

*FSIV = Full scale input voltage

Enter the calculated multiplier in the program.

Orientation of the 024A Wind Direction Sensor should be complete if the
024A counter weight was aligned due south.

5.3 Example Programs

024A Met-One Wind Direction Sensor

NOTE

'CR200(X) Series
'Created by Short Cut (2.5)

'Declare Variables and Units

Public Batt_Volt
Public WindDir
Public NewMult

Units Batt_Volt=Volts
Units WindDir=degrees

'Define Data Tables

DataTable(Table2,True,-1)
DataInterval(0,1440,Min)
Minimum(1,Batt_Volt,False,False)
EndTable

'Main Program

BeginProg
Scan(10,Sec)

'Default Datalogger Battery Voltage measurement Batt_Volt:

Battery(Batt_Volt)

'024A Wind Direction Sensor measurement WindDir:

ExDelSE(WindDir,1,1,1,2500,2000,1.0,0)
NewMult=360/WindDir

'Call Data Tables and Store Data

CallTable(Table2)
NextScan
EndProg

For these examples, the multiplier is listed as 1. The multiplier
is unique to individual devices. Follow the procedure provided
in Section 5.2 to acquire the correct multiplier for your sensor.

5

024A Met-One Wind Direction Sensor

'CR1000
'Created by Short Cut (2.5 Beta)

'Declare Variables and Units

Public Batt_Volt
Public WindDir
Public NewMult

Units Batt_Volt=Volts
Units WindDir=degrees

'Define Data Tables

DataTable(Table1,True,-1)
DataInterval(0,60,Min,10)
Sample(1,WindDir,FP2)
EndTable

DataTable(Table2,True,-1)
DataInterval(0,1440,Min,10)
Minimum(1,Batt_Volt,FP2,False,False)
EndTable

'Main Program

BeginProg
Scan(5,Sec,1,0)

'Default Datalogger Battery Voltage measurement Batt_Volt:

Battery(Batt_Volt)

'024A Wind Direction Sensor measurement WindDir:

BrHalf(WindDir,1,mV2500,1,1,1,2500,True,2000,250,1.0,0)
NewMult=360/WindDir

'Call Data Tables and Store Data

CallTable(Table1)
CallTable(Table2)
NextScan
EndProg

6

'CR3000
'Created by Short Cut (2.5)

'Declare Variables and Units

Public Batt_Volt
Public WindDir
Public NewMult

Units Batt_Volt=Volts
Units WindDir=degrees

'Define Data Tables

DataTable(Table1,True,-1)
DataInterval(0,60,Min,10)
Sample(1,WindDir,FP2)
EndTable

024A Met-One Wind Direction Sensor

DataTable(Table2,True,-1)
DataInterval(0,1440,Min,10)
Minimum(1,Batt_Volt,FP2,False,False)
EndTable

'Main Program

BeginProg
Scan(5,Sec,1,0)

'Default Datalogger Battery Voltage measurement Batt_Volt:

Battery(Batt_Volt)

'024A Wind Direction Sensor measurement WindDir:

BrHalf(WindDir,1,mV5000,1,1,1,5000,True,2000,250,1.0,0)
NewMult=360/WindDir

'Call Data Tables and Store Data

CallTable(Table1)
CallTable(Table2)
NextScan
EndProg

;{CR10X}
;

*Table 1 Program
01: 10 Execution Interval (seconds)

;Measure sensor. Multiplier is unique to individual devices.

1: Excite-Delay (SE) (P4)
1: 1 Reps
2: 14 250 mV Fast Range
3: 1 SE Channel
4: 1 Excite all reps w/Exchan 1
5: 2 Delay (0.01 sec units)
6: 500 mV Excitation
7: 1 Loc [ wind_dir ]
8: 1.0 Multiplier
9: 0.0 Offset

;Store measurements in final storage

2: If time is (P92)
1: 0000 Minutes (Seconds --) into a
2: 60 Interval (same units as above)
3: 10 Set Output Flag High (Flag 0)

3: Set Active Storage Area (P80)
1: 1 Final Storage Area 1
2: 101 Array ID

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

5: Sample (P70)
1: 1 Reps
2: 1 Loc [ wind_dir ]

7

024A Met-One Wind Direction Sensor

6. General Maintenance Schedule

6.1 6 to 12 Month Periodic Service *

Inspect sensor for physical damage and verify that the vane assembly rotates
freely. To verify parts and locations, refer to the parts diagram (Figure 6-2)
and the parts list (Table 6-1).

6.2 24 to 36 Month Service *

A complete factory overhaul of the sensor, including the replacement of the
potentiometer, is recommended. Contact Campbell Scientific and get a Return
Materials number (RMA) before sending it to Campbell Scientific.

* Schedule is based on average to adverse environments.

8

FIGURE 6-1. Cable Diagram

024A Met-One Wind Direction Sensor

FIGURE 6-2. Parts Diagram

9

024A Met-One Wind Direction Sensor

Item Part No. Description. Qty./Assy

1 102105 Vane Assembly 1
2 101685-1 Wind Dir. Support 1
3 101049-2 Label, Wind Dir. 1
4 101789 Label, Caution 1
5 860015 Screw, Shoulder 1
6 601100 Screw, Pan Hd Ph, 2-56x3/16 3
7 601680 Scrw, Set A/H, 8-32x3/8 2
8 101687 Label, Met-One 1
9 102017 Assy, Potentiometer 1
10 980495 Wire, 22Ga, Yel 1
11 980450 Wire, 22Ga, Blu 1

TABLE 6-1. Met-One Parts List Reproduced by

Campbell Scientific, Inc.

12 980475 Wire, 22Ga, Orn 1
13 995425 Loctite 222 A/R
14 500280 Connector, 6 Pin 1
15 995100 Adhesive, Epoxy A/R
16 995060 Adhesive, Silicone 5ml
17 510020 Cap 1
18
19
20
21 101806 Assembly, Cable Ref
22 101699 Assy Instructions Ref
23 101706 014 & 024 Installation Ref
24 101697 Wir. Diagram Ref
25
26 601850 Scrw, Cap A/H SS 10-32x5/8 1

10

7. References

024A Met-One Wind Direction Sensor

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.

11

024A Met-One Wind Direction Sensor

12

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/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 g et Tru e
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°

22 E

20 E

18 E

16 E

14 E

12 E

10 E

8 E

6 E

4 E

2 E

2 W

0

20 W

18 W

16 W

14 W

12 W

10 W

8 W

6 W

4 W

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

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