Campbell LP02 User manual

INSTRUCTION MANUAL
LP02 Pyranometer
Revision: 1/14
Copyright © 2006-2014
Campbell Scientific, Inc.

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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
3.1 Ships With............................................................................................1
3.2 Calibration Certificate..........................................................................1
4. Quickstart ....................................................................2
4.1 Siting Considerations ...........................................................................2
4.2 Mounting..............................................................................................2
4.3 Use SCWin to Program Datalogger and Generate Wiring Diagram ....5
5. Overview......................................................................8
6. Specifications .............................................................8
7. Operation...................................................................10
7.1 Wiring ................................................................................................10
7.2 Programming......................................................................................11
7.2.1 Input Range.................................................................................11
7.2.2 Multiplier ....................................................................................12
7.2.3 Offset ..........................................................................................12
7.2.4 Example Programs ......................................................................12
7.2.4.1 CR1000 Example Program...............................................13
7.2.4.2 CR10X Example Program................................................14
7.2.5 Output Format Considerations ....................................................15
8. Maintenance ..............................................................16
9. Troubleshooting........................................................16
Appendix
A. CM245 Adjustable Angle Mounting Stand............ A-1
A.1 Installation....................................................................................... A-1
Figures
4-1. CM225 Bracket Attached to a Crossarm..............................................2
4-2. CM225 Bracket Attached to a Mast .....................................................3
4-3. LP02 Mounting Hole............................................................................3
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Table of Contents
4-4. CM225 Bracket Mounting Holes ........................................................ 4
4-5. LP02 Pyranometer Attached to CM225 Solar Sensor Mounting
Stand ................................................................................................ 4
7-1. LP02 Schematic................................................................................. 10
A-1. CM245 bracket with 2.125 in. U-bolts positioned to mount the
pyranometer horizontally on a crossarm...................................... A-1
A-2. CM245 bracket with 1.5 in. U-bolts positioned to mount
pyranometer at a 40° angle on a vertical pipe .............................. A-2
Tables
7-1. Differential Connections to Campbell Scientific Dataloggers........... 10
7-2. Single-Ended Connections to Campbell Scientific Dataloggers........ 11
7-3. Multipliers Required for Flux Density and Total Fluxes................... 12
7-4. Wiring for Example Programs........................................................... 13
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LP02 Pyranometer
1. Introduction
The LP02 is an ISO-second-class pyranometer that monitors solar radiation for
the full solar spectrum range. It produces a millivolt signal that can be
measured directly by a Campbell Scientific datalogger. The LP02 can provide
solar radiation measurements for many meteorological applications. This
pyranometer is manufactured by Hukseflux.
Before using the LP02, please study:
•Section 2, Cautionary Statements
•Section 3, Initial Inspection
•Section 4, Quick Start
2. Cautionary Statements
•Although the LP02 is rugged, it is also a highly precise scientific
instrument and should be handled as such.
•Care should be taken when opening the shipping package to not damage or
cut the cable jacket. If damage to the cable is suspected, consult with a
Campbell Scientific application engineer.
3. Initial Inspection
•Upon receipt of the LP02, inspect the packaging and contents for damage.
File damage claims with the shipping company.
•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 correct product and cable length are received.
•See Section 3.1, Ships With, to ensure that all of your parts are included.
3.1 Ships With
(1) Bolt for mounting from original manufacturer
(2) Nuts for mounting from original manufacturer
(1) Calibration certificate (see Section 3.2, Calibration Certificate)
(2) Bolts for mounting from original manufacturer
(1) ResourceDVD
3.2 Calibration Certificate
Included with the sensor is a calibration certificate with the sensor calibration
constant and serial number. Cross check this serial number against the serial
number on your LP02 to ensure that the given calibration constant corresponds
to your sensor.
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LP02 Pyranometer
4. Quickstart
Please review Section 7, Operation, for wiring, CRBasic programming, and
Edlog programming.
4.1 Siting Considerations
The LP02 is usually installed horizontally, but can also be installed at any
angle including an inverted position. In all cases, it will measure the flux that
is incident on the surface that is parallel to the sensor surface.
Site the LP02 to allow easy access for maintenance while ideally avoiding any
obstructions above the plane of the sensing element. It is important to mount
the LP02 such that a shadow will not be cast on it at any time. If this is not
possible, try to choose a site where any obstruction over the azimuth range
between earliest sunrise and latest sunset has an elevation not exceeding 5°.
Diffuse solar radiation is less influenced by obstructions near the horizon. For
instance, an obstruction with an elevation of 5° over the whole azimuth range
of 360° decreases the downward diffuse solar radiation by only 0.8%.
4.2 Mounting
Below shows the steps for using the CM225 mounting bracket kit to mount the
LP02 to a vertical pipe (1.0 to 2.1 in. OD), or to a CM202, CM203, CM204, or
CM206 crossarm. If the sensor needs to be mounted at an angle, the CM245
Adjustable Angle Mounting Stand can be used instead (see Appendix A,
CM245 Adjustable Angle Mounting Stand).
1. Attach the CM225 to a mast or crossarm (see FIGURE 4-1 and FIGURE
4-2).
FIGURE 4-1. CM225 Bracket Attached to a Crossarm
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LP02 Pyranometer
FIGURE 4-2. CM225 Bracket Attached to a Mast
2. Place the LP02 in the center of the CM225 with the cable pointing to the
nearest magnetic pole, and align the sensor’s mounting holes with two of
the bracket’s mounting holes (see FIGURE 4-3 and FIGURE 4-4).
FIGURE 4-3. LP02 Mounting Hole
Mounting Hole
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LP02 Pyranometer
FIGURE 4-4. CM225 Bracket Mounting Holes
3. Place the mounting screws in the mounting holes and slightly tighten
them. The leveling screws should lightly touch the mounting plate (see
FIGURE 4-5).
FIGURE 4-5. LP02 Pyranometer Attached to CM225 Solar Sensor
Mounting Stand
4. Starting with the leveling screw nearest the bubble level, turn the leveling
screws to bring the bubble of the bubble level within the ring (see
FIGURE 4-5).
Mounting
Hole
Mounting
Hole
Mounting
Hole
Bubble Level
(3) Leveling Screws
CM225 Solar
Sensor
Mounting Stand
(2) Mounting Screws
CM200 Series
Crossarm
LP02 Pyranometer
Cable Tie
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LP02 Pyranometer
5. Tighten the mounting screws to secure the assembly in its final position.
6. Route the sensor cable to the instrument enclosure.
7. Use cable ties to secure the cable to CM225 bracket and to the vertical
pipe or crossarm and tripod/tower (see FIGURE 4-5).
4.3 Use SCWin to Program Datalogger and Generate Wiring
Diagram
The simplest method for programming the datalogger to measure the LP02 is to
use Campbell Scientific’s SCWin Program Generator.
1. Open Short Cut and click on New Program.
2. Select the Datalogger Model and enter the Scan Interval.
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LP02 Pyranometer
3. Select LP02 Pyranometer, and select the right arrow (in center of
screen) to add it to the list of sensors to be measured, and then select Next.
4. Enter the Sensitivity supplied on the manufacturer’s certificate of
calibration; this sensitivity is unique to each sensor. The public variables
defaults can typically be used. After entering the information, click on
OK, and then select Next.
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LP02 Pyranometer
5. Choose the Outputs and then select Finish.
6. In the Save As window, enter an appropriate file name and select Save.
7. In the Confirm window, click Yes to download the program to the
datalogger.
8. Click on Wiring Diagram and wire according to the wiring diagram
generated by Short Cut.
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LP02 Pyranometer
5. Overview
The LP02 pyranometer is designed for continuous outdoor use. Due to its flat
spectral sensitivity from 280 to 3000 nm, it can be used in natural sunlight,
under plant canopies, in green houses or buildings, and inverted to measure
reflected solar radiation. Two LP02s can be used in combination to measure
albedo. The LP02 can also be used to measure most types of artificial light
(Xenon lamps, Halogen lamps, etc.).
The LP02 pyranometer consists of a thermopile sensor, housing, dome, and
cable. The thermopile is coated with a black absorbent coating. The paint
absorbs the radiation and converts it to heat. The resultant temperature
difference is converted to a voltage by the copper-constantan thermopile. The
thermopile is encapsulated in the housing in such a way that it has a field of
view of 180 degrees and the angular characteristics needed to fulfill the cosine
response requirements.
The LP02’s cable has a user-specified length that can terminate in:
•Pigtails that connect directly to a Campbell Scientific datalogger
(cable termination option –PT).
•Connector that attaches to a prewired enclosure (cable termination
option –PW).
•Connector that attaches to a CWS900 Wireless Sensor Interface (cable
termination option –CWS). The CWS900 enables the pyranometer to
be used in a wireless sensor network.
6. Specifications
Features:
•Compatible with most Campbell Scientific dataloggers
•Measures reflected solar radiation when inverted
•Provides measurements in direct sunlight, under plant canopies, when
the sky is cloudy, and in artificial light
•Includes bubble level and leveling screws eliminating need for a
separate leveling base, which simplifies installation
•Compatible with the CWS900-series interfaces, allowing it to be used
in a wireless sensor network
•Acceptable for providing the solar radiation data used in stability
estimations
•Dome protects thermopile and allows water to roll off of it
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LP02 Pyranometer
Compatible Dataloggers: CR800
CR850
CR1000
CR3000
CR9000(X)
CR5000
CR23X
CR10(X)
CR510
CR500
21X
CR7
Overall classification according to ISO
9060 / WMO:
Second class pyranometer
Response time for 95% response:
18 s
Zero offset (response to 200 W m–2 net
thermal radiation):
<15 W m–2
Zero offset (response to 5 K/h change
in ambient temperature):
<4 W m–2
Non-stability:
<1% change per year
Non-linearity:
<±1% (100 to 1000 W m–2)
Directional response for beam
radiation:
within ±25 W m–2
Spectral selectivity:
±5% (280 to 3000 nm)
Temperature response
(within an interval of 50°C):
±3% (–10° to +40°C)
Tilt response:
within ±2%
Sensitivity (nominal):
15 μV(W m–2)
Expected voltage output:
0.1 to +50 mV in natural sunlight
Operating temperature range:
–40° to +80°C
Sensor resistance:
Between 40 and 60 Ω
Range:
0 to 2000 W m–2
Cable replacement:
Cable can be replaced by the user
Spectral range:
280 to 3000 nm (50% transmission
points)
Leveling:
Level and leveling feet included
Expected accuracy for daily sums:
±10%
Dome diameter:
3 cm (1.2 in)
Height:
5.9 cm (2.3 in)
Body diameter:
7.8 cm (3.1 in)
Weight with 15 ft cable:
363 g (0.8 lb)
1Guide to Meteorological Instruments and Methods of Observation, fifth
edition, WMO, Geneva and ISO9060
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LP02 Pyranometer
7. Operation
7.1 Wiring
A schematic diagram of the LP02 is shown in FIGURE 7-1.
White
Green
Clear
FIGURE 7-1. LP02 Schematic
When Short Cut is used to create the datalogger program, the sensor should be
wired to the channels shown in the wiring diagram created by Short Cut.
A differential voltage measurement is recommended because it has better noise
rejection than a single-ended measurement. If a differential channel is not
available, a single-ended measurement can be used.
Connections to Campbell Scientific dataloggers for a differential measurement
are given in TABLE 7-1. A user-supplied jumper wire should be connected
between the low side of the differential input and ground (AG or
) to keep
the signal in common mode range.
Connections to Campbell Scientific dataloggers for a single-ended
measurement are given in TABLE 7-2.
TABLE 7-1. Differential Connections to Campbell Scientific Dataloggers
Color
Description
CR9000(X)
CR5000
CR3000
CR1000
CR800
CR850
CR510
CR500
CR10(X)
21X
CR7
CR23X
White Signal (+) DIFF Analog High DIFF Analog High DIFF Analog High
Green Signal (–) *DIFF Analog Low *DIFF Analog Low *DIFF Analog Low
Clear Shield G
* Jumper to AG or
with user supplied wire.
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LP02 Pyranometer
TABLE 7-2. Single-Ended Connections to Campbell Scientific Dataloggers
Color
Description
CR9000(X)
CR5000
CR3000
CR1000
CR800
CR850
CR510
CR500
CR10(X)
21X
CR7
CR23X
White Signal (+) Single-Ended Analog Single-Ended Analog Single-Ended Analog
Green Signal (–) AG
Clear Shield G
7.2 Programming
This section is for users who write their own datalogger programs. A
datalogger program to measure this sensor can be created using Short Cut.
You do not need to read this section to use Short Cut.
Solar radiation can be reported as an average flux density (W m–2) or daily total
flux density (MJ m–2). The appropriate multipliers are listed in TABLE 7-3.
Programming examples are given for both average and daily total solar
radiation.
The LP02 outputs a low level voltage ranging from 0 to a maximum of up to
35 mV, in natural light, depending on the calibration factor and radiation level.
A differential voltage measurement is recommended because it has better noise
rejection than a single-ended measurement. If a differential channel is not
available, a single-ended measurement can be used. The acceptability of a
single-ended measurement can be determined by simply comparing the results
of single-ended and differential measurements made under the same
conditions.
7.2.1 Input Range
The output voltage of the LP02 is usually between 10 and 35 mV per
1000 W m–2. When estimating the maximum likely value of sensor output, a
maximum value of solar radiation of 1100 W m–2 can be used for field
measurements on a horizontal surface.
Select the input range as follows:
1. Estimate the maximum expected input voltage by multiplying the
maximum expected irradiance (W m–2) by the calibration factor (µV/
W m–2). Divide the answer by 1000 to give the maximum in millivolt
units.
2. Select the smallest input range which is greater than the maximum
expected input voltage. Normally the 50 mV range for the CR3000,
CR9000(X), CR5000, CR7, CR23X, 21X, and the 25 mV or 250 mV
range for the CR800, CR850, CR1000, CR10X, CR510, and CR500 will
be suitable. The exact range will depend on the sensitivity of your
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LP02 Pyranometer
individual sensor and the maximum expected reading. With some
dataloggers, an autorange option can be used if measurement time is not
critical.
The parameter code for the input range also specifies the measurement
integration time. The slow or 60 Hz rejection integration gives a more noise-
free reading. A fast integration takes less power and allows for faster
throughput.
7.2.2 Multiplier
The multiplier converts the millivolt reading to engineering units. The
calibration supplied by the manufacturer gives the output of the sensor (c) as
microvolts (V x 10–6)per W m–2. As the datalogger voltage measurement
instructions give a default output in mV, the following equation should be used
to calculate the multiplier (m) to give the readings in W m–2:
m = 1000/c
Other units can be used by adjusting the multiplier as shown in TABLE 7-3.
TABLE 7-3. Multipliers Required for Flux Density and Total Fluxes
Units Multipliers Output Processing
W m–2 m Average
MJ m–2 M•t•0.000001 Total
kJm–2 M•t•0.001 Total
cal cm–2 M•t•0.0239*0.001 Total
cal cm–2 min–1 M•1.434•0.001 Average
m = calibration factor in W m-2/mV
t = datalogger program execution interval in seconds
7.2.3 Offset
The offset will normally be fixed at zero as the sensor should output no
significant signal in dark conditions. In practice, because of the nature of
thermopile detector sensors, there will be some offset in dark conditions;
sometimes this offset can give negative light readings. This offset varies with
several factors (for example, rate of change of sensor temperature), so it cannot
be removed with a fixed offset. Some users may wish to remove small
negative readings by including code after the measurement instructions that
sets negative readings to zero.
7.2.4 Example Programs
The following programs measure the LP02 every 10 seconds and convert the
mV output to W m–2 and MJ m–2. A sensor calibration of 15.02 µV per W m–2
is used for the example programs. Both programs output an hourly average
flux (W m–2), and a daily total flux density (MJ m–2).
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LP02 Pyranometer
Wiring for the examples is given in TABLE 7-4.
TABLE 7-4. Wiring for Example Programs
Color Description CR1000 CR10X
White Signal (+) DIFF Analog High DIFF Analog High
Green Signal (–) *DIFF Analog Low *DIFF Analog Low
Clear Shield G
* Jumper to AG or
with user supplied wire.
7.2.4.1 CR1000 Example Program
'CR1000
'Declare Variables and Units
Public Solar_Wm2
Public Solar_MJ
Units Solar_Wm2=W/m²
Units Solar_MJ=MJ/m²
'Hourly Data Table
DataTable(Table1,True,-1)
DataInterval(0,60,Min,10)
Average(1,Solar_Wm2,FP2,False)
EndTable
'Daily Data Table
DataTable(Table2,True,-1)
DataInterval(0,1440,Min,10)
Totalize(1,Solar_MJ,IEEE4,False)
EndTable
'Main Program
BeginProg
Scan(10,Sec,1,0)
'LP02 Pyranometer measurement in Wm-2:
'The Multiplier (m) for this example is based upon a sensor calibration (c) of
'15.02 µV/Wm-2, and will be different for each sensor.
'Multiplier (m) = 1000/c = 66.577896.
VoltDiff(Solar_Wm2,1,mV25,1,True,0,_60Hz,66.577896,0) ‘use the 50 mV range for the
CR3000, CR5000 and CR9000
'Set negative readings to zero:
If Solar_Wm2<0 Then Solar_Wm2=0
'Calculate units in MJ, where MJ = m * t * 0.000001. m = Solar_Wm2 from above, and
't = 10 (scan interval)
Solar_MJ=Solar_Wm2*0.00001
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LP02 Pyranometer
'Call Data Tables and Store Data
CallTable(Table1)
CallTable(Table2)
NextScan
EndProg
7.2.4.2 CR10X Example Program
;{CR10X}
*Table 1 Program
01: 10.0000 Execution Interval (seconds)
; LP02 measurement in Wm-2
1: Volt (Diff) (P2)
1: 1 Reps
2: 23 25 mV 60 Hz Rejection Range ;use the 50 mV range for the CR7, 21X and CR23X
3: 1 DIFF Channel ;use the 250 mV range for the CR10X if
4: 3 Loc [ Solar_Wm2 ] calibration factor is > 25 µV/Wm-2
5: 66.5778 Multiplier
6: 0 Offset
; Set negative values to zero
2: If (X<=>F) (P89)
1: 3 X Loc [ Solar_Wm2 ]
2: 4 <
3: 0 F
4: 30 Then Do
3: Z=F x 10^n (P30)
1: 0 F
2: 0 n, Exponent of 10
3: 3 Z Loc [ Solar_Wm2 ]
4: End (P95)
; Calculate units in MJ, where MJ = m * t * 0.000001.
; m = Solar_Wm2 from above, and t = 10 (scan interval).
5: Z=X*F (P37)
1: 3 X Loc [ Solar_Wm2 ]
2: .00001 F
3: 4 Z Loc [ Solar_MJ ]
6: 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)
7: Set Active Storage Area (P80)
1: 1 Final Storage Area 1
2: 101 Array ID
8: Real Time (P77)
1: 1220 Year,Day,Hour/Minute (midnight = 2400)
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