Campbell Scientific P2546A-L User Manual

P2546A-L Anemometer

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Copyright © 2012

Campbell Scientific, Inc.

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33

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Table of Contents

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

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

2. Cautionary Statements...............................................1

3. Initial Inspection .........................................................1

4. Quickstart .................................................................... 2

4.1 Step 1 — Mount the Sensor .................................................................2

4.2 Step 2 — Use SCWin ShortCut to Program Datalogger and

Generate Wiring Diagram.................................................................3

5. Overview......................................................................5

6. Specifications .............................................................6

6.1 Calibration............................................................................................7

6.2 Switching Characteristics.....................................................................7

7. Installation...................................................................7

7.1 Wiring ..................................................................................................7

7.2 Programming........................................................................................8

7.2.1 Example Program..........................................................................9

8. Troubleshooting........................................................10

9. Maintenance ..............................................................10

10. References ................................................................11

Figures

4-1. 27739 pole mounted to a crossarm via the CM220..............................2

5-1. P2546A Anemometer...........................................................................5

Tables

7-1. Connections to Campbell Scientific Dataloggers Pulse Channels .......8

7-2. Connections to Campbell Scientific Dataloggers Control Ports...........8

7-3. Wind Speed Multiplier and Offset .......................................................9

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P2546A-L Anemometer

1. Introduction

The P2546A is a Class 1 anemometer used in wind energy applications. It
primarily provides wind speed resource assessment, and wind turbine power
performance monitoring. Wind speed is sensed by a three-cup rotor assembly.
Magnets mounted on the shaft cause a switch to close and open two times per
revolution. Our dataloggers measure the switch closure and convert the signal
to engineering units (mph, m/s, knots).

Before using the P2546A-L Anemometer, please study

• Section 2. Cautionary Statements

• Section 3. Initial Inspection

• Section 4. Quickstart

More details are available in the remaining sections.

2. Cautionary Statements

• The P2546A is a precision instrument. Please handle it with care.

• If the P2546A is to be installed at heights over 6 feet, be familiar with

tower safety and follow safe tower climbing procedures.

• Danger — Use extreme care when working near overhead electrical wires.

Check for overhead wires before mounting the P2546A or before raising a
tower.

3. Initial Inspection

• Upon receipt of the P2546A, inspect the packaging and contents for

damage. File damage claims with the shipping company. Immediately
check package contents against the shipping documentation. Contact
Campbell Scientific about any discrepancies.

• The model number and cable length are printed on a label at the

connection end of the cable. Check this information against the shipping
documents to ensure the expected product and cable length are received.

• Each P2546A anemometer is shipped with a MEASNET calibration

certificate that contains information concerning where the anemometer
was calibrated, the calibration procedure used, the calibration equation
obtained, and the serial number of the anemometer. Cross check the serial
number in the calibration certificate against the serial number on the
anemometer to ensure that the given sensitivity value corresponds to your
sensor.

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P2546A-L Anemometer

4. Quickstart

4.1 Step 1 — Mount the Sensor

To mount the sensor, do the following.

1. Mount a CM202, CM204, or CM206 crossarm to a tripod or tower.

2. Orient the crossarm north-south, with the CM220 Mount on the north end.

3. Place the 27739 30 inch pole in the bottom of the P2546A.

4. Place the bottom of the 27739 pole in the CM220's u-bolt and tighten the

nuts (see FIGURE 4-1).

5. Use a bubble level to ensure that the anemometer is level.

6. Route the sensor cable along the underside of the crossarm to the tripod or

tower, and to the instrument enclosure.

7. Secure the cable to the 27739 pole, crossarm, and tripod or tower using

cable ties.

2

FIGURE 4-1. 27739 pole mounted to a crossarm via the CM220

P2546A-L Anemometer

4.2 Step 2 — Use SCWin ShortCut to Program Datalogger and Generate Wiring Diagram

The simplest method for programming the datalogger to measure an P2546A is
to use Campbell Scientific's SCWin Short Cut Program Generator.

1. Open Short Cut and click on New Program.

2. Select datalogger and enter scan interval.

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P2546A-L Anemometer

3. Select P2546A and select the right arrow to add it to the list of sensors to

be measured then select next.

4. Select the outputs then select finish.

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P2546A-L Anemometer

5. Wire according to the wiring diagram generated by SCWin Short Cut.

5. Overview

The P2546A-L cup anemometer is a sturdy device that senses wind speed with
a three-cup rotor assembly (see FIGURE 5-1). Permanent magnets mounted on
the shaft cause a switch to close and open two times per revolution. The switch
has no bounce, and is equipped with a special mechanism that reduces the
variation in operating time over the frequency range. This feature facilitates
obtaining instantaneous wind speed by measuring the time interval of each
revolution.

FIGURE 5-1. P2546A Anemometer

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P2546A-L Anemometer

The P2546A anemometer is manufactured by Windsensor and cabled by
Campbell Scientific. Lead length for the P2546A is specified when the sensor
is ordered.

The P2546A's cable can terminate in:

6. Specifications

Features:

• Pigtails that connect directly to a Campbell Scientific datalogger

(option –PT).

• Connector that attaches to a prewired enclosure (option –PW). Refer

to www.campbellsci.com/prewired-enclosures for more information.

• Calibration — The P2546A-L is shipped with a MEASNET

certificate containing information about where the anemometer was
calibrated, the calibration procedure used, the calibration equation
obtained, and the serial number of the anemometer.

• Quality — Constructed only of durable materials such as anodized

aluminum and stainless steel.

NOTE

Compatibility

Dataloggers: CR800 / 850, CR1000, CR3000, CR5000,

CR10(X), CR510, CR23X, 21X, CR7

The specifications are based on 80 wind tunnel calibrations
performed according to the Measnet Cup Anemometer
Calibration Procedure. The specified offset and gain figures
represent the mean values of these calibrations. Variation among
units designates the maximum deviation of any unit from the
straight line representing these mean values. All units are run-in
for 225 hours at 9 m/s, in order to reduce the initial bearing
friction to a level close to the steady state value. After run-in,
bearing friction is tested at –15 °C and at room temperature. The
allowed limits for this test assures that the temperature influence
on the calibration is within the specified limit.

Starting Threshold: < 0.4 m/s

Starting Speed: 0.27 m/s

Gain: 0.6201 m

Distance Constant: λ0 = 1.81 ± 0.04 m

6

Standard Deviation of Offset: 0.014 m/s

Standard Deviation of Gain: 0.027 m

Variation Among Units: ±1%

Nonlinearity: < 0.04 m/s

Temperature Influence
(-15° to 60°C): < 0.05 m/s

6.1 Calibration

Standard: U=A0+B0×f ,
Where:
U=Wind speed in m/s
f = Output frequency in Hz
A0 = 0.27 m/s
B

6.2 Switching Characteristics

Signal Type: potential free contact closure

Duty Cycle: 40% to 60%

Maximum Switching Voltage: 30 V

= 0.620 m

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P2546A-L Anemometer

7. Installation

7.1 Wiring

Maximum Recommended
Switching Current: 10 mA

Series Resistance: 330 Ω, 1 W

Operating Temperature: –35° to 60°C

Locate wind sensors away from obstructions (e.g., trees and building). As a
general rule, there should be a horizontal distance of at least ten times the
height of the obstruction between the wind set and the obstruction. If mounting
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 10 for a list
of references that discuss siting wind speed and direction sensors. For power
performance applications, refer to IEC 61400-12-1 which specifies the
mounting and location of anemometers.

Connections to Campbell Scientific dataloggers are given in TABLE 7-1 and
TABLE 7-2. When Short Cut program generator software is used to create the
datalogger program, wire the sensor to the datalogger as directed by the wiring
diagram created by Short Cut.

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P2546A-L Anemometer

TABLE 7-1. Connections to Campbell Scientific Dataloggers

Pulse Channels

Color

White Signal Pulse Pulse Pulse

Brown Signal Reference

Clear Shield

TABLE 7-2. Connections to Campbell Scientific Dataloggers

Color

White Signal C1-C8 C6-C8

Brown Signal Reference 5V 5V

Clear Shield

Wire Label

Wire Label

CR800
CR850
CR5000
CR3000
CR1000

Control Ports

CR510
CR500
CR10X

G

G

CR800
CR850
CR5000
CR3000
CR1000

21X
CR7
CR23X

CR10X

G

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7.2 Programming

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.

Wind speed is typically measured an a datalogger pulse channel. The P2546A
uses the CRBasic PulseCount() instruction configuring the pulse channel for
switch closure with frequency counting. For dataloggers programmed with
EDLOG, specify configuration code 22 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

The following table lists the multiplier and offset to obtain meters per second
(m/s) when the pulse count instruction is configured to output the result in Hz.

Standard Calibration is listed below. Using the MEASNET calibration will
give measurements in m/s. MEASNET calibration multiplier and offset will
be listed on the MEASNET calibration sheet included with each sensor.

Model m/s

P2546A Multiplier = 0.6207

7.2.1 Example Program

The following CR1000 example program uses a pulse port to measure the
P2546A once a second. The program stores the mean, maximum, minimum,
and standard deviation of the measured wind speed over a 10 minute interval.
Wiring for the example is given in the following table.

P2546A-L Anemometer

TABLE 7-3. Wind Speed Multiplier and Offset

Offset = 0.27

'Pulse Port Example

'CR1000 Series Datalogger
'Program to measure P2546A and store ten minute averages

'Wiring
' Datalogger
'Color Description Channel
'----- ----------- -------
'Brown Signal Reference P1
'White Signal
'Clear Shield

Const P2546A_mult = .6201
Const p2546a_offset = .27

Public PTemp, batt_volt
Public P2546A

'Define Data Tables
DataTable (Test,1,1000)
DataInterval (0,10,Min,10)
Minimum (1,batt_volt,FP2,0,False)
Sample (1,PTemp,FP2)
Average (1,P2546A,FP2,False)
Maximum (1,P2546A,FP2,False,False)
Minimum (1,P2546A,FP2,False,False)
StdDev (1,P2546A,FP2,False)
EndTable

'Main Program

BeginProg
Scan (1,Sec,0,0)
PanelTemp (PTemp,250)
Battery (batt_volt)

'Measure P2546A and correct measurement if wind speed is zero
PulseCount (P2546A,1,1,2,1,P2546A_mult,p2546a_offset)
If P2546A <= p2546a_offset Then P2546A = 0

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P2546A-L Anemometer

'Call data tables
CallTable Test

NextScan
EndProg

8. Troubleshooting

Symptom: No wind speed

1. Check that the sensor is wired to the pulse channel specified by the pulse

count instruction.

2. Verify that the Configuration Code, and Multiplier and Offset parameters

for the Pulse Count instruction are correct for the datalogger type.

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.

9. Maintenance

Every month do a visual/audio inspection of the anemometer at low wind
speeds. Verify that the anemometer bearing 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.

CAUTION

Disassembling an anemometer to change the bearings will
invalidate the MEASNET calibration.

MEASNET calibrations are normally valid for 12 months in the field
(assuming the anemometer is installed within 6 months of the calibration test).
In high-accuracy applications, Campbell Scientific recommends that the
anemometer be returned to us for maintenance/overhaul between deployments;
we can arrange for a new MEASNET calibration after maintenance/overhaul
where required.

Before the anemometer is sent to Campbell Scientific, the customer must get
an RMA (returned material authorization) and fill out the Declaration of
Hazardous Material and Decontamination form.

10

10. References

P2546A-L Anemometer

IEC 61400 Part 12-1, “Wind turbine generator systems Part 12: Wind Turbine

Power Performance Testing”.

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.

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P2546A-L Anemometer

12

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