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Campbell CNR4 User Manual
Summary of CNR4
Page 1
Cnr4 cnr4 net radiometer issued: 29.7.13 copyright © 2000-2013 campbell scientific, inc. Printed under licence by campbell scientific ltd. Csl 874 user manual.
Page 3: Guarantee
Guarantee this equipment is guaranteed against defects in materials and workmanship. This guarantee applies for twelve months from date of delivery. We will repair or replace products which prove to be defective during the guarantee period provided they are returned to us prepaid. The guarantee will...
Page 5: Please Read First
Please read first about this manual please note that this manual was originally produced by campbell scientific inc. Primarily for the north american market. Some spellings, weights and measures may reflect this origin. Some useful conversion factors: area: 1 in 2 (square inch) = 645 mm 2 length: 1 ...
Page 7: Contents
I 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. General description..................................................... 1 2. Sensor specifications ....................................
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Ii 9. Maintenance and recalibration ................................ 29 9.1 cleaning windows and domes .............................................................. 29 9.2 recalibration .......................................................................................... 29 9.3 replacing the d...
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Iii tables 5-1. Resistance values versus cnr4's thermistor temperature in °c ........... 11 5-2. Resistance values versus cnr4's pt-100 temperature in °c ................. 12 6-1. Datalogger connections for differential measurement ........................ 16 6-2. Datalogger connections for single-e...
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Iv.
Page 11: Cnr4 Net Radiometer
1 cnr4 net radiometer 1. General description the cnr4 is a four component net radiometer that measures the energy balance between the incoming short-wave and long-wave radiation versus the surface- reflected short-wave and outgoing long-wave radiation. The cnr4 net radiometer consists of a pyranomet...
Page 12: 2. Sensor Specifications
Cnr4 net radiometer 2 the design of cnr4 is such that the short-wave radiation and the long-wave radiation are measured separately. The short-wave radiation is measured by two pyranometers, one for measuring incoming short-wave radiation from the sky, and the other, which faces downward, for measuri...
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User manual 3 figure 2-2. The cnr4 net radiometer with cnf 4 heater/ventilator unit, top view. 2.1 cnr4 specifications sensor sensitivities: four probes have unique sensitivity values. Please refer to the calibration sheets or label on the bottom of the sensor for the sensitivity values. Operating t...
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Cnr4 net radiometer 4 wrr traceable calibration certificate for pyranometers wrr traceable calibration certificate for pyrgeometers extra calibration sticker (to be put on cnf4, if used) cnf4 package includes: cnf4 heater/ventilator cnf4 cable 2.2 pyranometer specifications * indicates iso specifica...
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User manual 5 typical signal output for atmospheric application: 0 to 15 mv impedance: 20 to 200 Ω, typically 50Ω detector: copper-constantan multi junction thermopile level accuracy: 1 degree irradiance: 0 to 2000 w/m 2 spectral selectivity: uncertainty in daily total: instrument calibration: indoo...
Page 16: 3. Installation
Cnr4 net radiometer 6 2.4 optional cnf4 heater/ventilator the purpose of the heater/ventilator is to prevent dew deposition on the pyrgeometer and pyrgeometer window, thus enhancing the measurement accuracy and reliability. Using the heater/ventilator will have negligible effect on the pyranometer r...
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User manual 7 3. Insert the mounting rod of the cnr4 sensor into the mounting block of the mounting bracket, making sure the sensor points to the direction of the arrows marked as “sensor” on top of the bracket (see figure 3-2). Perform a coarse levelling of the sensor using the bubble level on the ...
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Cnr4 net radiometer 8 figure 3-2. Attaching the cnr4 onto the mounting rod (010759) using vertical pole or horizontal crossarm. For installation in buildings or in solar energy applications, one will often have to mount the cnr4 parallel to the surface that is being studied. This may be in a tilted ...
Page 19: Mode
User manual 9 5. Using the cnr4 in the four separate components mode in the four separate components mode configuration (measuring two short-wave radiation signals, two long-wave signals), all signals are measured separately. Calculation of net-radiation and albedo can be done on-line by the datalog...
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Cnr4 net radiometer 10 for the pyrgeometer only e = v/c + 5.67*10 -8 * t 4 (5-2) in this equation c is the sensitivity of the sensor. Please bear in mind that t is in kelvin, and not in celsius or fahrenheit. The downward-facing pyrgeometer measures the far infrared radiation that is emitted by the ...
Page 21
User manual 11 alternatively, you can use the pt-100 to make the temperature measurement. In order to make the temperature measurement, using the pt-100 sensor, you will need one current excitation channel, and one differential analogue channel. Please refer to appendix c for a sample program to mea...
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Cnr4 net radiometer 12 table 5-2. Resistance values versus cnr4's pt-100 temperature in °c. Temperature [°c] resistance [ Ω] temperature [°c] resistance [ Ω] temperature [°c] resistance [ Ω] -30 -29 -28 -27 -26 -25 -24 -23 -22 -21 -20 -19 -18 -17 -16 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -...
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User manual 13 the calculation of the albedo can also serve as a tool for quality control of your measured data at the specific site. 5.5 calculation of net short-wave radiation the net short-wave solar radiation is equal to the incoming (downwelling) short- wave radiation minus the reflected (upwel...
Page 24: 6. Wiring
Cnr4 net radiometer 14 where e upper/lower pyranometers are calculated according to equation 5-1, and e upper/lower pyrgeometers are calculated according to equation 5-2. The terms with t cancel each other out. 6. Wiring the cnr4 has two outputs for the short-wave radiation, two outputs for the long...
Page 25
User manual 15 the four radiation outputs can be measured using differential or single-ended inputs on the datalogger. A differential voltage measurement is recommended because it has better noise rejection than a single-ended measurement. When differential inputs are used, jumper the low side of th...
Page 26: 7. Datalogger Programming
Cnr4 net radiometer 16 table 6-1. Datalogger connections for differential measurement function wire colour cr1000 cr3000/cr5000 pyranometer up signal red differential input (h) differential input (h) pyranometer up reference *blue differential input (l) differential input (l) pyranometer down signal...
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User manual 17 7.1 sensor sensitivity unlike the cnr1, the cnr4 comes with four different sensor sensitivity values for four separate probes. The cnr4 sensor comes with two copies of ‘certificate of calibration’ by the manufacturer that show the sensor serial number and sensitivity values for four i...
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Cnr4 net radiometer 18 'cr1000 series datalogger ' '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...
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User manual 19 'voltage excitation ' 'ex1 ' 'ex2 cnr4 thermistor voltage excitation (red) ' 'ex3 ' 'cnr4 sensor public logger_temp, batt_volt public cnr4(4) alias cnr4(1) = short_up alias cnr4(2) = short_dn alias cnr4(3) = long_up alias cnr4(4) = long_dn public cnr4_t_c 'cnr4 thermistor temperature ...
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Cnr4 net radiometer 20 'cnr4 multipliers public cnr4_mult(4) const pyranometer_up_mult = 1000/pyranometer_up_sensitivity '(w/m^2/mv) const pyranometer_dn_mult = 1000/pyranometer_dn_sensitivity '(w/m^2/mv) const pyrgeometer_up_mult = 1000/pyrgeometer_up_sensitivity '(w/m^2/mv) const pyrgeometer_dn_mu...
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User manual 21 albedo = short_dn/short_up 'compute net radiation rn = rs_net + rl_net calltable cnr4_data calltable cnr4_ts nextscan endprog 7.2.2 example 2, cr3000 program using differential measurements the program example 2 requires four differential channels to measure the four radiation outputs...
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Cnr4 net radiometer 22 'wiring instructions ' 'analog channels '1h cnr4 pyranometer upper signal (red) '1l cnr4 pyranometer upper signal reference (blue) 'gnd jumper to 1l ' '2h cnr4 pyranometer lower signal (white) '2l cnr4 pyranometer lower signal reference (thin black) 'gnd jumper to 2l ' '3h cnr...
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User manual 23 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_sensitivi...
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Cnr4 net radiometer 24 scan (1,sec,3,0) paneltemp (logger_temp,250) battery (batt_volt) 'cnr4 radiation measurements 'cnr4 thermistor measurement brhalf (vs_vx,1,mv5000,16,vx1,1,2500,true ,0,250,1.0,0) rs = 1000*(vs_vx/(1-vs_vx)) cnr4_t_c = 1/(1.0295e-3+2.391e-4*ln(rs)+1.568e-7*(ln(rs))^3)-273.15 'c...
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User manual 25 average cnr4 thermistor temperature (kelvin) average corrected long-wave radiation (pyrgeometer up) average corrected long-wave radiation (pyrgeometer down) average short-wave net radiation average long-wave net radiation average albedo average net radiation 'cr5000 series datalogger ...
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Cnr4 net radiometer 26 'cnr4 sensor public logger_temp, batt_volt public cnr4(4) alias cnr4(1) = short_up alias cnr4(2) = short_dn alias cnr4(3) = long_up alias cnr4(4) = long_dn public cnr4_t_c 'cnr4 thermistor temperature in celsius public cnr4_t_k 'cnr4 thermistor temperature in kelvin public lon...
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User manual 27 average (1,albedo,ieee4,false) average (1,rn,ieee4,false) 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) = pyra_up_mult cnr4_mult(...
Page 38: 8. Troubleshooting
Cnr4 net radiometer 28 8. Troubleshooting if there is no indication as to what may be the problem, start performing the following "upside-down test", which is a rough test for a first diagnosis. It can be performed both outdoors and indoors. Indoors, a lamp can be used as a source for both short-wav...
Page 39
User manual 29 the cnr4 body and ambient air should be at the same temperature as much as possible. 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, we suggest putting ...
Page 40
Cnr4 net radiometer 30 please contact campbell scientific, to obtain an rma number for recalibration. 9.3 replacing the drying cartridge the cnr4 has a drying cartridge inside the sensor to help keep the electronics dry. The manufacturer recommends that this drying cartridge be replaced every 6 to 1...
Page 41: Conditions
A-1 appendix a. Cnr4 performance and measurements under different conditions below, table a-1 shows what one might typically expect to measure under different meteorological conditions. The first parameter is day and night. At night, the solar radiation is zero. The second column shows if it is clou...
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Cnr4 net radiometer a-2 figure a-1. Different measurement conditions and signals. Upper pyrgeometer day with alternating cloud fields ‐180 ‐170 ‐160 ‐150 ‐140 ‐130 ‐120 ‐110 ‐100 ‐90 ‐80 ‐70 ‐60 ‐50 ‐40 ‐30 ‐20 ‐10 0 10 20 30 0:00 :00 1:00 :00 2:00 :00 3:00 :00 4:00 :00 5:00 :00 6:00 :00 7:00 :00 8:...
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Appendix a. Cnr4 performance and measurements under different conditions a-3 upwelling signal (downward facing) pyrgeometer ‐30 ‐20 ‐10 0 10 20 30 0: 00: 00 1: 00: 00 2: 00: 00 3: 00: 00 4: 00: 00 5: 00: 00 6: 00: 00 7: 00: 00 8: 00: 00 9: 00: 00 10 :00: 00 11 :00: 00 12 :00: 00 13 :00: 00 14 :00: 0...
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Cnr4 net radiometer a-4 4 / 1 8 10 67 . 5 ⎥⎦ ⎤ ⎢⎣ ⎡ ⋅ = − cg3 upper e ature sky temper (b-1) 4 / 1 8 10 67 . 5 ⎥⎦ ⎤ ⎢⎣ ⎡ ⋅ = − cg3 lower e e temperatur ground (b-2).
Page 45: B.1 General Information
B-1 appendix b. Cnf4 heater/ventilator whenever the heater is used, the hea ting may cause errors in th e measurement of the sensor temperature. Under most conditions the accuracy that is gained by heating will be larger than the errors that are introduced by heating. In both the pyranometer and the...
Page 46: To Cnr4
Appendix b. Cnf4 heater/ventilator b-2 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. Connect the power gro...
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Appendix b. Cnf4 heater/ventilator b-3 2. Attach the heater/ventilator unit unto the bottom of the cnr4 sensor, using the three pan-head screws and washers, as shown in figure b-2. Make sure that the pyranometer and the pyrgeometer windows are not scratched during the installation. Figure b-2. Attac...
Page 48
Appendix b. Cnf4 heater/ventilator b-4 3. Make sure the cables are cleared from the edges of the cnf4, as shown in figure b-3, and place the white solar shield over it. Use the four flat-head screws provided to complete the solar shield installation to the cnf4, as shown in figure b-4 and b-5. Figur...
Page 49
Appendix b. Cnf4 heater/ventilator b-5 figure 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...
Page 50: B.3 Wiring
Appendix b. Cnf4 heater/ventilator b-6 b.3 wiring the following table shows the recommended datalogger wiring for using the cnr4 sensor with the cnf4 heater/ventilator while making the differential measurement. Table b-1. Cr1000 and cr3000 datalogger connections for differential measurement with hea...
Page 51
Appendix b. Cnf4 heater/ventilator b-7 do not use the sw12 channel of a cr1000 or cr3000 to simultaneously power the heater and ventilator. Simultaneously powering the heater and ventilator will exceed the current limit of the sw12 channel. If the heater and ventilator need to be used at the same ti...
Page 52
Appendix b. Cnf4 heater/ventilator b-8 ' 'g cnf4 ventilator - (blue) ' cnf4 heater - (yellow) ' 'gnd ventilator & heater shield (clear) pipelinemode 'cnr4 sensor public logger_temp, batt_volt public flag(2) as boolean public cnr4(4) alias cnr4(1) = short_up alias cnr4(2) = short_dn alias cnr4(3) = l...
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Appendix b. Cnf4 heater/ventilator b-9 cardout (1,-1) minimum (1,batt_volt,fp2,0,false) sample (1,logger_temp,fp2) average (4,cnr4(1),ieee4,false) average (1,cnr4_t_c,ieee4,false) average (1,cnr4_t_k,ieee4,false) average (1,long_up_corr,ieee4,false) average (1,long_dn_corr,ieee4,false) average (1,rs...
Page 54
Appendix b. Cnf4 heater/ventilator b-10 'cnf4 heater control - the heater will be turned on when flag(2) is set high sw12 (2,flag(2)) calltable cnr4_data calltable cnr4_ts nextscan endprog b.5 cnf4 heater/ventilator maintenance b.5.1 testing the heater the optional cnf4 consists of a heater and a ve...
Page 55
C-1 appendix c. Cr3000 program for measuring pt-100 temperature sensor the program example c measures the pt-100 sensor for the body temperature of the cnr4. This program requires four differential channels to measure the four radiation outputs, and one current excitation channel and one differentia...
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Cnr4 net radiometer c-2 'cr3000 series datalogger ' 'cnr4 program 'this program measures 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 downloadin...
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Appendix c. Cr3000/cr5000 program that controls the heater c-3 public cnr4_t_c 'cnr4 thermistor temperature in celsius public cnr4_t_k 'cnr4 thermistor temperature in kelvin public long_up_corr 'downwelling long-wave radiation with temperature correction public long_dn_corr 'upwelling long-wave radi...
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Cnr4 net radiometer c-4 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...
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