Campbell CNR4 Instruction Manual
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Campbell CNR4 Instruction Manual

Net radiometer
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CNR4 Net Radiometer
Revision: 9/13
C o p y r i g h t
©
2 0 0 0 - 2 0 1 3
C a m p b e l l
S c i e n t i f i c ,
I n c .

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  • Page 1 CNR4 Net Radiometer Revision: 9/13 C o p y r i g h t © 2 0 0 0 - 2 0 1 3 C a m p b e l l S c i e n t i f i c ,...
  • Page 3 WARRANTY AND ASSISTANCE This equipment is warranted by CAMPBELL SCIENTIFIC (CANADA) CORP. ("CSC") to be free from defects in materials and workmanship under normal use and service for ***** twenty-four (24) months from date of shipment unless specified otherwise. ***** Batteries are not warranted.
  • Page 4 PLEASE READ FIRST About this manual Please note that this manual was originally produced by Campbell Scientific Inc. (CSI) primarily for the US market. Some spellings, weights and measures may reflect this origin. Some useful conversion factors: Area: 1 in...

  • Page 5: Table Of Contents

    Pyrgeometer Specifications..............11 Optional CNF4 Heater/Ventilator ............12 6.4.1 CNF4 Specifications ..............12 7. Operation ..............13 Using the CNR4 in the Four Separate Components Mode....13 7.1.1 Measuring Short-wave Solar Radiation with Pyranometer ..13 7.1.2 Measuring Long-wave Far Infrared Radiation with Pyrgeometer................13 7.1.3 Measuring CNR4 Temperature with Thermistor ......14 7.1.4 Calculation of Albedo ..............16...
  • Page 6 7-1. The CNR4 sensor with SOLAR and TEMP cables ......18 7-2. The marks on the end of the CNR4: S for SOLAR cable, and T for TEMP cable................19 7-3. Labels on the pigtail end of the SOLAR cable ........19 7-4.
  • Page 7 Table of Contents B-2. Attaching the CNF4 to CNR4 using pan-head screws and washers ..................B-4 B-3. Making sure the cables are clear from the edges......B-5 B-4. CNF4 solar shield and four flat-head screws ........B-5 B-5. Attaching the solar shield to CNF4 using four flat-head screws ..B-6 B-6.
  • Page 8 Table of Contents...

  • Page 9: Introduction

    CNR4 Net Radiometer Introduction The CNR4 is a research-grade net radiometer that measures the energy balance between incoming and outgoing radiation. Our dataloggers measure the CNR4’s output. This net radiometer offers a professional solution for scientific-grade energy balance studies. Before using the CNR4, please study:...

  • Page 10: Quickstart

    3. Orient the sensor towards the nearest pole to avoid potential problems from shading. Mounting A mounting bracket kit, pn 26120, is used to mount the CNR4 directly to a vertical pipe, or to a CM202, CM203, CM204, or CM206 crossarm. Mount the sensor as follows: 1.

  • Page 11: Attaching The Cnr4 Onto The Mounting Rod (Pn 26120) Using Vertical Pole Or Horizontal Crossarm

    2. Attach the 26120 mounting bracket to the vertical mounting pipe, or CM200-series crossarm using the provided U-bolt (see FIGURE 4-2). FIGURE 4-2. Attaching the CNR4 onto the mounting rod (pn 26120) using vertical pole or horizontal crossarm 3. Insert the sensor’s support arm into the mounting block of the mounting bracket kit.

  • Page 12: Use Scwin To Program Datalogger And Generate Wiring Diagram

    Use SCWin to Program Datalogger and Generate Wiring Diagram The simplest method for programming the datalogger to measure the CNR4 is to use Campbell Scientific’s SCWin Program Generator. The SCWin example provided here uses the thermistor to NOTE provide the temperature correction.
  • Page 13 CNR4 Net Radiometer 2. Select the datalogger and enter the scan interval. 3. Select CNR4 Net Radiometer, and select the right arrow (in center of screen) to add it to the list of sensors to be measured, and then select Next.
  • Page 14 CNR4 Net Radiometer 4. Enter the sensitivity values supplied on the manufacturer’s certificate of calibration; these sensitivity values are unique to each sensor. The public variables defaults can typically be used. After entering the information, click on OK, and then select Next.

  • Page 15: Overview

    The pyranometer pair measures short-wave solar radiation, and the pyrgeometer pair measures long-wave far infrared radiation. The upper long- wave detector of CNR4 has a meniscus dome to ensure that water droplets roll off easily while improving the field of view to nearly 180°, compared with a 150°...

  • Page 16: Specifications

    An optional ventilation unit with a heater, CNF4, is designed as an extension of the solar shield and can be fitted to the CNR4 or retrofitted later. The heater/ventilation unit is compact and provides efficient air-flow over the domes and windows to minimize the formation of dew and to reduce the frequency of cleaning.

  • Page 17: The Cnr4 Net Radiometer With Cables And Mounting Rod, Top View

    CNR4 Net Radiometer The properties of the CNR4 are mainly determined by the properties of the individual probes. Generally the accuracy of the CNR4 will be higher than that of competitive net-radiometers, because the solar radiation measurement performed by the pyranometer is accurate, and offers a traceable calibration.

  • Page 18: Cnr4 Specifications

    CNR4 Net Radiometer CNR4 Specifications Four probes with unique sensitivity Sensor sensitivities: values. Please refer to the calibration sheets or label on the bottom of the sensor for the sensitivity values. –40 to +80°C (–40 to 176°F) Operating temperature: 0 to 100% RH Operating humidity: <...

  • Page 19: Pyrgeometer Specifications

    CNR4 Net Radiometer < 20 W/m at angle up to 80° with Directional error*: 1000 W/m Zero offset due to 0 to -200 W/m < 15 W/m IR net irradiance*: Zero offset due to temperature < 3 W/m (5 K/hr temperature change) change*: <...

  • Page 20: Optional Cnf4 Heater/Ventilator

    CNR4 Net Radiometer Field of view 180 degrees Upper: 150 degrees Lower: –250 to +250 W/m Net-irradiance: < 1% (sensitivity change per year) Non-stability: < 6 W/m (1000 W/m solar Window heating offset: irradiance) < 10% (95% confidence level) indoor...

  • Page 21: Operation

    T, into account. This is why the temperature sensors are incorporated in the CNR4’s body near the pyrgeometer sensing element, and has, therefore, the same temperature as the pyrgeometer sensor surface. The calculation of the long-wave far infrared irradiance, E, is done according to Equation 7-2.

  • Page 22: Measuring Cnr4 Temperature With Thermistor

    7.1.3 Measuring CNR4 Temperature with Thermistor The CNR4 has two temperature sensors built inside: thermistor and Pt-100; both have identical accuracy. Using the thermistor is recommended when using Campbell Scientific dataloggers. The thermistor has a greater resistance (10 k @ 25°C) than Pt-100 sensor (100...
  • Page 23 8523 2854 Relatively small errors occur when the CNR4 is not in thermal equilibrium. This happens for example when the heater is on, or when the sun is shining. When the heater and ventilator are on, the largest expected deviation between the real sensor temperature and the thermistor reading is 1 degree.

  • Page 24: Calculation Of Albedo

    CNR4 Net Radiometer TABLE 7–2. Resistance values versus CNR4’s Pt–100 temperature in °C. Temperature Resistance Temperature Resistance Temperature Resistance [°C] [°C] [°C] –30 88.22 100.00 111.67 –29 88.62 100.39 112.06 –28 89.01 100.78 112.45 –27 89.40 101.17 112.83 –26 89.80 101.56...

  • Page 25: Calculation Of Net Short-Wave Radiation

    Therefore, if one is only interested in the net long-wave radiation, instead of separate upper and lower components of the long-wave radiation, the CNR4 temperature measurement is not required. The E measured with the pyrgeometer actually represents the irradiance of the sky (for upward-facing pyrgeometer) or the ground (for downward-facing pyrgeometer).

  • Page 26: Calculation Of Net (Total) Radiation

    CNR4. The wiring diagrams for the thermistor in this manual is applicable only if the CNR4 and the cables were purchased from Campbell Scientific, Inc.

  • Page 27: The Marks On The End Of The Cnr4: S For Solar Cable, And T For Temp Cable

    CNR4 Net Radiometer FIGURE 7-2. The marks on the end of the CNR4: S for SOLAR cable, and T for TEMP cable The measurement details for Pt-100 sensor, including the wiring diagram and sample program, are explained in Appendix C, CR3000 Program for Measuring Pt-100 Temperature Sensor.

  • Page 28: Labels On The Pigtail End Of The Temp Cable

    CNR4 Net Radiometer FIGURE 7-4. Labels on the pigtail end of the TEMP cable. TABLE 7-3. Datalogger Connections for Differential Measurement Function Wire Color CR1000 CR3000/CR5000 Pyranometer Up Signal Differential Input (H) Differential Input (H) Pyranometer Up R eference *Blue...

  • Page 29: Datalogger Programming

    Datalogger Pro gram ming The CNR4 outputs four voltages that typically range from 0 to 15 mV for the pyranometers, and 5 mV for the pyrgeometers. A differential voltage measurement is recommended because it has better noise rejection than a single-ended measurement.
  • Page 30 'Search for the text string "unique" to find places to enter the sensitivity values. 'Wiring Instructions 'ANALOG CHANNELS CNR4 Pyranometer Upper signal (red) CNR4 Pyranometer Upper signal reference (blue) 'gnd jumper to 1L CNR4 Pyranometer Lower signal (white) CNR4 Pyranometer Lower signal reference (black)
  • Page 31 Units albedo = W/m^2 Units Rn = W/m^2 Dim Rs, Vs_Vx 'CNR4 sensitivities: refer to the Certificate of Calibration from Kipp & Zonen for sensitivity values 'for each probes, and enter them below. Const pyranometer_up_sensitivity = 15.35 'unique sensitivity for upper pyranometer '(microV/W/m^2) Const pyranometer_dn_sensitivity = 15.41...

  • Page 32: Example 2, Cr3000 Program Using Differential Measurements

    (pyranometer up) rage short-wave radiation (pyranometer down) rage long-wave radiation (pyrgeometer up) Aver age long-wave radiation (pyrgeometer down) Average CNR4 thermistor temperature (degrees C) Average CNR4 thermistor temperature (Kelvin) Average corrected long-w ave radiation (pyrgeometer up) Average corrected long-w...
  • Page 33 'CNR4 program 'This program measures CNR4 four-component net radiometer 'This program also measures the thermistor inside the CNR4 'User must enter the sensitivity values for all four probes in the program and save/compile 'prior to downloading it to the datalogger.
  • Page 34 Units albedo = W/m^2 Units Rn = W/m^2 Dim Rs, Vs_Vx 'CNR4 sensitivities: refer to the Certificate of Calibration from Kipp & Zonen for sensitivity values 'for each probes, and enter them below. Const pyranometer_up_sensitivity = 15.35 'unique sensitivity for upper pyranometer '(microV/W/m^2) Const pyranometer_dn_sensitivity = 15.41...

  • Page 35: Example 3, Cr5000 Program Using Differential Measurements

    (pyranometer down) Average long-wave radiation (pyrgeometer up) Average long-wave radiation (pyrgeometer down) Average CNR4 thermistor temperature (degrees C) Average CNR4 thermistor temperature (Kelvin) Average corrected long-wave radiation (pyrgeometer up) Average corrected long-wave radiation (pyrgeometer dow Average short-wave net radiation...
  • Page 36 'CNR4 program 'This program measures CNR4 four-component net radiometer 'This program also measures the thermistor inside the CNR4 'User must enter the sensitivity values for all four probes in the program and save/compile 'prior to downloading it to the datalogger.
  • Page 37 Units albedo = W/m^2 Units Rn = W/m^2 Dim Rs, Vs_Vx 'CNR4 sensitivities: refer to the Certificate of Calibration from Kipp & Zonen for sensitivity values 'for each probes, and enter them below. Const pyra_up_sensitiv = 15.35 'unique sensitivity for upper pyranometer (microV/W/m^2) Const pyra_dn_sensitiv = 15.41...

  • Page 38: Troubleshooting

    CNR4 Net Radiometer 'Convert CNR4 temperature to Kelvin cnr4_T_K = cnr4_T_C+273.15 'Correct the long-wave radiation values from pyrgeometers long_up_corr = long_up+5.67e-8*cnr4_T_K^4 long_dn_corr = long_dn+5.67e-8*cnr4_T_K^4 'Compute short-wave net radiation Rs_net = short_up - short_dn 'Compute long-wave net radiation Rl_net = long_up - long_dn...

  • Page 39: Testing The Pyrgeometer

    (see second tes t in Section 8.1, Testing the Pyranometer). The CNR4 body and the ambient air should be at the same temperature. Let the pyrgeometer rest for at least five minutes to regain its thermal equilibrium. Set the voltmeter to its most sensitive range. To test if the pyrgeometer is working properly, put your hand in front of the pyrgeometer.

  • Page 40: Maintenance And Recalibration

    Replacing the Drying Cartridge The CNR4 has a drying cartridge inside the sensor to help keep the electronics dry. The manufacturer recommends replacing the drying cartridge every 6 to 12 months. The three screws holding the white solar shield and the six...

  • Page 41: Replacement Parts

    Drying Cartridge Rubber Gasket FIGURE 9-1. Replacing the drying cartridge Replaceme nt Parts The following is the list of replacement parts for the CNR4 and CNF4 (heater/ventilator) available from Campbell Scientific. CSI Part Number Description CNR4CBL1-L Replacement CNR4 Solar Cable...
  • Page 42 CNR4 Net Radiometer...

  • Page 43: Cnr4 Performance And Measurements Under Different Conditions

    This can roughly be attributed to the water vapor in the air, which is a major contributor to the far infrared radiation. TABLE A-1. Typical output signals of CNR4 under different meteorological conditions. Explanation can be found in the text.
  • Page 45 Appendix A. CNR4 Performance and Measurements under Different Conditions Upwelling Signal (Downward Facing) Pyrgeometer upwelling signal (downward facing) pyrgeometer Pyrgeometer: U emf / sensitivity [W/m²] Temp of instrument [°C] GURE A-3. Clear day for the downwa rd facing pyrgeometer It is ass...
  • Page 46 Appendix A. CNR4 Performance and Measurements under Different Conditions upper Temperatur (A-1) lower Ground Temperatur (A-2)

  • Page 47: Cnf4 Heater/Ventilator

    Appendix B. CNF4 Heater/Ventilator Whenever the heater is used, the heating may cause errors in the NOTE measurement of the sensor temperature. Under most conditions, the accuracy gained by heating will be larger than the errors introduced by heating. In both the pyranometer and the pyrgeometer, thermal sensors are used, and these sensors, in principle, measure a heat flow.
  • Page 48 1 hour after sunrise. The heater power can be controlled using one of the SW12V channels of the Campbell Scientific dataloggers. The heater’s current drain is approximately 850 mA at 12 Vdc (10 watts). The ventilator draws additional 5 watts of power at 12 Vdc.

  • Page 49: Attaching The Optional Cnf4 Heater/Ventilator Unit To Cnr4

    Appendix B. CNF4 Heater/Ventilator B.2 Attaching the Optional CNF4 Heater/Ventilato Unit to CNR4 1. The CNF4 heater/ventilator unit comes with the following: the heater/ventilator, the white solar shield, three pan-head screws with washers, and four flat-head screws as shown in FIGURE B-1.

  • Page 50: Attaching The Cnf4 To Cnr4 Using Pan-Head Screws And

    Appendix B. CNF4 Heater/Ventilator 2. Attach the heater/ventilator unit unto the bottom of the CNR4 sensor, using the t hree pan-head scre ws and washers, as shown in FIGURE B-2. Make sure that the pyranometer and the pyrgeometer windows are not scratched during the installation.

  • Page 51: B-3. Making Sure The Cables Are Clear From The Edges

    Appendix B. CNF4 Heater/Ventilator 3. Make sure the cables are cleared from the edges of the CNF4, as show n in FIGURE B-3, and place the white solar shield over it. Use the four fl ead screws provided to complete the solar shield installation to the CNF4, as show n in FIGURE B-4 and FIGURE B-5.

  • Page 52: B-5. Attaching The Solar Shield To Cnf4 Using Four Flat-Head Screws

    4. Once the CNF4 heater/ventilator unit is attached to the bottom side of the CNR4, the CNF4 will cover the label that contains the serial number and the sensitivity values for the four sensors. Affix the extra label that came with the sensor to the bottom side of the CNF4’s anodized aluminium base...

  • Page 53: Wiring

    Appendix B. CNF4 Heater/Ventilator B.3 Wiring The following table shows the recommended datalogger wiring for using the CNR4 sensor with the CNF4 heater/ventilator while m aking the differential measurement. TABLE B-1. CR1000 and CR3000 Datalogger Connections for Differential Measurement with...

  • Page 54: Example B, Cr3000 Datalogger Program With Heater/Ventilator Control

    'CR3000 Series Datalogger 'CNR4 program 'This program measures CNR4 four-component net radiometer 'This program also measures the thermistor inside the CNR4 'In addition this program controls heater and ventilator using separate SW12V-1 and SW12V-2 channels 'The heater and ventilator are turned on/off by setting flag(1), and flag(2) high and low, respectively.
  • Page 55 Units albedo = W/m^2 Units Rn = W/m^2 Dim Rs, Vs_Vx 'CNR4 sensitivities: refer to the Certificate of Calibration from Kipp & Zonen for sensitivity values 'for each probes, and enter them below. Const pyranometer_up_sensitivity = 15.35 'unique sensitivity for upper pyranometer '(microV/W/m^2) Const pyranometer_dn_sensitivity = 15.41...
  • Page 56 EndTable DataTable (cnr4_ts,True,-1) DataInterval (0,1,Sec,10) CardOut (1,-1) Sample (4,cnr4(1),IEEE4) Sample (1,cnr4_T_K,IEEE4) EndTable BeginProg 'Load the multiplier values for the CNR4 cnr4_mult(1) = pyranometer_up_mult cnr4_mult(2) = pyranometer_dn_mult cnr4_mult(3) = pyrgeometer_up_mult cnr4_mult(4) = pyrgeometer_dn_mult Scan (1,Sec,3,0) PanelTemp (logger_temp,250) Battery (batt_volt) 'CNR4 radiation measurements...

  • Page 57: Cnf4 Heater/Ventilator Maintenance

    The filter can be cleaned with warm clean water, or can be replaced with the new one. You can purchase the replacement filters, pn 26010, from Campbell Scientific. B-11...
  • Page 58 Appendix B. CNF4 Heater/Ventilator B-12...

  • Page 59: Temperature Sensor

    60 minutes. It also stores the raw time-series ata from CNR4 to data table called cnr4_ts. Minimum battery voltage Sample datalogger panel temperature...
  • Page 60 'CR3000 Series Dat logger 'CNR4 program 'This program meas res CNR4 four-component net radiometer 'This program also measures the Pt-100 sensor inside the CNR4 'User must enter the sensitivity values for all four probes in the program and save/compile 'prior to download ng it to the datalogger.
  • Page 61 Units albedo = W/m^2 Units Rn = W/m^2 Dim cnr4_prt_R, Rs_R0 'CNR4 sensitivities: refer to the Certificate of Calibration from Kipp & Zonen for sensitivity values 'for each probes, and enter them below. Const pyranometer_up_sensitivity = 15.35 'unique sensitivity for upper pyranometer '(microV/W/m^2) Const pyranometer_dn_sensitivity = 15.41...
  • Page 62 Appendix C. CR3000 Program for Measuring Pt-100 Temperature Sensor 'PRT (Pt-100) temperature m easurement Resistance (cnr4_prt_R,1,mV200,8,Ix1,1,1500,True,True,0,_60Hz,1,0) Rs_R0 = cnr4_prt_R/100 PRT (cnr4_T_C,1,Rs_R0,1,0) 'Convert CNR4 temperature to Kelvin cnr4_T_K = cnr4_T_C+273.15 'Correct the long-wave radiation values from pyrgeometers long_up_corr = long_up+5.67e-8*cnr4_T_K^4 long_dn_corr = long_dn+5.67e-8*cnr4_T_K^4 'Compute short-wave net radiation...
  • Page 64 Campbell Scientific Ltd. (CSL Germany) Fahrenheitstraße 13 28359 Bremen GERMANY • info@campbellsci.de www.campbellsci.de Campbell Scientific Spain, S. L. (CSL Spain) Avda. Pompeu Fabra 7-9, local 1 08024 Barcelona SPAIN • info@campbellsci.es www.campbellsci.es Please visit www.campbellsci.com to obtain contact information for your local US or international representative.

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