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1. Measurement range 0 to 4000 W m Sensitivity range 7 to 25 x 105 V W m Sensitivity nominal 12 x 10 V W m Expected voltage output application under natural solar radiation 0 1 to 50 X 10 W Measurement function reguired programming E U S Optional measurement function reguired programming for correction of sensitivity as a function of instrument body temperature E U So a T 2 b T c Measurement function optional programming for sunshine duration programming according to WMO guide paragraph 8 2 2 Reguired readout 1 differential voltage channel or 1 single ended voltage channel input resistance gt 10 Q Internal temperature sensor measuring the body temperature version code T1 for Pt100 DIN class A version code T2 for thermistor 10 kQ at 25 C Optional readout 1 temperature channel in case the temperature sensor is used Rated operating temperature range 40 to 80 C Sensor resistance range 100 to 200 Q Required sensor power zero passive sensor Spectral range 20 transmission points 190 to 4000 x 10 m Standard governing use of the instrument ISO TR 9901 1990 Solar energy Field pyranometers Recommended practice for use ASTM G183 05 Standard Practice for Field Use of Pyranometers Pyrheliometers and UV Radiometers Standard cable length see options 5m Cable diameter 5
2. SR22 manual v1506 29 43 Hukseflux Thermal Sensors 7 4 Data quality assurance Quality assurance can be done by e analysing trends in solar irradiance signal e plotting the measured irradiance against mathematically generated expected values e comparing irradiance measurements between sites e analysis of night time signals The main idea is that one should look out for any unrealistic values There are programs on the market that can semi automatically perform data screening See for more information on such a program http www dqms com SR22 manual v1506 30 43 Hukseflux Thermal Sensors SR22 manual v1506 31 43 Hukseflux Thermal Sensors 8 Appendices 8 1 Appendix on cable extension replacement The sensor cable of SR22 is equipped with a M16 straight connector In case of cable replacement it is recommended to purchase a new cable with connector at Hukseflux An alternative is to choose for a Do it yourself DIY approach please ask for the DIY connector assembly guide In case of cable extension the user may choose purchasing a new cable with connector at Hukseflux or extending the existing cable himself Please note that Hukseflux does not provide support for DIY connector and cable assembly SR22 is equipped with one cable Keep the distance between data logger or amplifier and sensor as short as possible Cables act as a source of distortion by picking up capacitive noise In an electrically quiet envi
3. 6 In uncertainty analysis for modern pyrheliometers tilt dependence often is so low that one single typical observation may be sufficient 7 In case of special measurement conditions typical specification values are chosen These should for instance account for the measurement conditions shaded unshaded ventilated unventilated horizontal tilted and environmental conditions clear sky cloudy working temperature range 8 Among the various sources of uncertainty some are correlated i e present during the entire measurement process and not cancelling or converging to zero when averaged over time the off diagonal elements of the covariance matrix are not zero Paragraph 5 2 of GUM 9 Among the various sources of uncertainty some are uncorrelated cancelling or converging to zero when averaged over time the off diagonal elements of the covariance matrix are zero Paragraph 5 1 of GUM 10 Among the various sources of uncertainty some are not included in analysis this applies for instance to non linearity for pyranometers because it is already included in the directional error and the spectral response for pyranometers and pyrheliometers because it is already taken into account in the calibration process SR22 manual v1506 25 43 Hukseflux Thermal Sensors Table 6 4 1 1 Preliminary estimates of achievable uncertainties of measurements with Hukseflux pyranometers The estimates are based on typical pyr
4. In an irradiance measurement by definition the response to beam radiation varies with the cosine of the angle of incidence i e it should have full response when the solar radiation hits the sensor perpendicularly normal to the surface sun at zenith 0 angle of incidence zero response when the sun is at the horizon 90 angle of incidence 90 zenith angle and 50 of full response at 60 angle of incidence A pyranometer should have a so called directional response older documents mention cosine response that is as close as possible to the ideal cosine characteristic SR22 is responsive to the total solar spectrum 190 to 4000 x 10 m According to the ISO 9060 specification a pyranometer should cover the spectral range from 350 to 1500 x 10 m with a spectral selectivity that is as flat as possible In order to attain the proper directional and spectral characteristics a pyranometer s main components are e athermal sensor with black coating It has a flat spectrum covering the 190 to 50000 x 10 m range and has a near perfect directional response The coating absorbs all solar radiation and at the moment of absorption converts it to heat The heat flows through the sensor to the sensor body The thermopile sensor generates a voltage output signal that is proportional to the solar irradiance e a quartz dome This dome limits the spectral range from 190 to 4000 x 10 m cutting off the part above 400
5. 2 Check if the sensor reacts to light put the multimeter at its most sensitive range of DC voltage measurement typically the 100 x 10 VDC range or lower Expose the sensor to a strong light source for instance a 100 W light bulb at 0 1 m distance The signal should read gt 2 x 10 V now Darken the sensor either by putting something over it or switching off the light The instrument voltage output should go down and within one minute approach O V 3 Remove the sun screen see chapter on installation of the sun screen Inspect the bubble level 4 Inspect the instrument for any damage 5 Inspect if the humidity indicator is blue Blue indicates dryness The colour pink indicates it is humid in the latter case replace the desiccant see chapter on maintenance SR22 manual v1506 8 43 Thermal Sensors 4 Hukseflux 2 Instrument principle and theory Figure 2 1 Overview of SR22 cable standard length 5 metres optional longer cable fixation of sun screen thumb screw inner quartz dome thermal sensor with black coating outer quartz dome sun screen humidity indicator desiccant holder levelling feet bubble level connector SR22 manual v1506 9 43 Hukseflux Thermal Sensors SR22 s scientific name is pyranometer A pyranometer measures the solar radiation received by a plane surface from a 180 field of view angle This quantity expressed in W m is called hemispherical solar radiation
6. 0 is by definition the cable exit direction also called north east is 90 ASTM G113 09 Sunshine duration sunshine duration during a given period is defined as the sum of that sub period for which the direct solar irradiance exceeds 120 W m ref WMO SR22 manual v1506 39 43 Hukseflux Thermal Sensors 8 10 Appendix on converting resistance to temperature SR22 is equipped with an internal temperature sensor This can be either a Pt100 SR22 T1 version or a 10 kQ thermistor SR22 T2 version as ordered Both versions require the user to measure the resistance of the temperature sensor and convert this value to temperature Many dataloggers have built in functions to perform such a conversion In case the user wishes to calculate temperature in degrees Celsius from resistance in Ohms himself there are two distinct procedures SR22 T1 T1 versions are equipped with a Pt100 platinum resistance thermometer It is classified as class A according to DIN EN 60751 It has a resistance of 100 Q at a temperature of 0 C To convert resistance in Q to temperature in C one can use the following equation R A a 4B 1 Pt100 Formula 8 10 1 2B T with Rpizoo the resistance in Q T the temperature in C A and B the Pt100 coefficients A 3 908 x 10 B 5 775 x 107 SR22 T2 T2 versions are equipped with a 10 kQ thermistor of type 44031RC It has a resistance of 10000 Q at a temperature of
7. 2 Trouble shooting Table 7 2 1 Trouble shooting for SR22 The sensor does not give any signal Check the electrical resistance of the sensor between the green and white wire Use a multimeter at the 1000 Q range Measure the sensor resistance first with one polarity than reverse the polarity Take the average value The typical resistance of the wiring is 0 1 Q m Typical resistance should be the typical sensor resistance of 100 to 200 Q plus 1 5 Q for the total resistance of two wires back and forth of each 5 m Infinite resistance indicates a broken circuit zero or a low resistance indicates a short circuit Check if the sensor reacts to light put the multimeter at its most sensitive range of DC voltage measurement typically the 100 x 10 VDC range or lower Expose the sensor to strong light source for instance a 100 W light bulb at 1 x 107m distance The signal should read gt 2 x 10 V now Darken the sensor either by putting something over it or switching off the light The instrument voltage output should go down and within one minute approach 0 V Check the data acquisition by applying a 1 x 10 V source to it in the 1 x 10 V range Check the condition of the connectors on chassis as well as the cable The sensor signal is unrealistically high or low Note that night time signals may be negative down to 5 W m on clear windless nights due to zero offset a Check if the pyranometer has clean do
8. 25 C To convert resistance in Q to temperature in C one can use the Steinhart Hart equation Measure the resistance of the thermistor and then calculate the temperature from the resistance 1 T 1111 1 273 15 Formula 8 10 2 a p In Rthermistor Y In Rthermistor with Rtnermistor the thermistor resistance in Q T the temperature in C a B and y the Steinhart Hart coefficients 1 0295 x 10 a B 2 391 x 10 y 1 568 x107 SR22 manual v1506 40 43 Hukseflux Thermal Sensors 8 11 EC declaration of conformity We Hukseflux Thermal Sensors B V Delftechpark 31 2628 XJ Delft The Netherlands in accordance with the reguirements of the following directive 2004 108 EC The Electromagnetic Compatibility Directive hereby declare under our sole responsibility that Product model SR22 Type Pyranometer has been designed to comply and is in conformity with the relevant sections and applicable reguirements of the following standards Emission EN 61326 1 2006 Immunity EN 61326 1 2006 Emission EN 61000 3 2 2006 Emission EN 61000 3 3 1995 Al 2001 A2 2005 jo o O lt I N Kees VAN DEN BOS Director Delft July 14 2015 SR22 manual v1506 41 43 2015 Hukseflux Thermal Sensors B V www hukseflux com Hukseflux Thermal Sensors B V reserves the right to change specifications without notice
9. 3x 10 m Chassis connector M16 panel connector male thread 10 pole Chassis connector type HUMMEL AG 7 840 200 000 panel connector front mounting short version Cable connector M16 straight connector female thread 10 pole Cable connector type HUMMEL AG 7 810 300 00M straight connector female thread for cable 3 to 6 x 10 m special version Connector protection class IP 67 IP 69 K per EN 60 529 connected Cable replacement replacement cables with connector can be ordered separately from Hukseflux Mounting 2 x M5 bolt at 65 x 10 m centre to centre distance on north south axis or 1 x M6 bolt at the centre of the instrument connection from below under the bottom plate of the instrument Levelling bubble level and adjustable levelling feet are included Levelling accuracy lt 0 1 bubble entirely in ring Desiccant two bags of silica gel 0 5 g 35 x 20 mm Humidity indicator blue when dry pink when humid IP protection class IP 67 SR22 manual v1506 13 43 Hukseflux Thermal Sensors Table 3 1 1 Specifications of SR22 started on previous pages Gross weight including 5 m cable 2 05 kg Net weight including 5 m cable 0 85 kg Packaging HPRC casing of 255 x 225 x 165 mm HEATING Heater operation the heater is not necessarily switched on recommended operation is to activate the heater when the sun is below the horizon Requ
10. evaluation Maintenance and trouble shooting Recommended maintenance and guality assurance Trouble shooting Calibration and checks in the field Data guality assurance Appendices Appendix on cable extension replacement Appendix on tools for SR22 Appendix on spare parts for SR22 Appendix on standards for classification and calibration Appendix on calibration hierarchy Appendix on meteorological radiation guantities Appendix on ISO and WMO Classification tables Appendix on definition of pyranometer specifications Appendix on terminology glossary Appendix on converting resistance to temperature EC declaration of conformity SR22 manual v1506 OONN NU PA W N 3 43 Hukseflux Thermal Sensors List of symbols Quantities Voltage output Sensitivity Sensitivity at reference conditions Temperature Electrical resistance Solar irradiance Solar radiant exposure Time in hours Temperature coefficient Temperature coefficient Temperature coefficient Resistance of Pt100 Pt100 coefficient Pt100 coefficient Resistance of 10 kQ thermistor Steinhart Hart coefficient Steinhart Hart coefficient Steinhart Hart coefficient see also appendix 8 6 on meteorological quantities SR22 manual v1506 Symbol o oO TIMP AVUNC ow R Pt100 A B R thermistor a B Y Unit V V W m V W m C Q W m W h m h 1 C 1 C Q Q 4 43 Hukseflux Thermal Sensors Introductio
11. is a minor layer of moisture that is hardly visible replace the desiccant and wait a few days to see if the situation improves In case of condensation of droplets disassemble the instrument and dry out the parts The inner dome shows internal condensation Arrange to send the sensor back to Hukseflux for diagnosis SR22 manual v1506 28 43 Hukseflux Thermal Sensors 7 3 Calibration and checks in the field Recalibration of field pyranometers is typically done by comparison in the field to a reference pyranometer The applicable standard is ISO 9847 International Standard Solar Energy calibration of field pyranometers by comparison to a reference pyranometer At Hukseflux an indoor calibration according to the same standard is used Hukseflux recommendation for re calibration if possible perform calibration indoor by comparison to an identical reference instrument under normal incidence conditions In case of field comparison ISO recommends field calibration to a higher class pyranometer Hukseflux suggests also allowing use of sensors of the same model and class because intercomparisons of similar instruments have the advantage that they suffer from the same offsets It is therefore just as good to compare to pyranometers of the same brand and type as to compare to an instrument of a higher class ISO recommends to perform field calibration during several days 2 to 3 days under cloudless conditions 10 days un
12. resistance lt 0 1 Q m Length cables should be kept as short as possible in any case the total cable length should be less than 100 m Outer sheath with specifications for outdoor use for good stability in outdoor applications SR22 manual v1506 32 43 Hukseflux Thermal Sensors 8 2 Appendix on tools for SR22 Table 8 2 1 Specifications of tools for SR22 tooling required for sun screen fixation and removal by hand tooling required for bottom plate fixation and removal hex key 2 5 mm tooling required for desiccant holder fixation and removal spanner size 20 mm tooling required for wire fixation and removal internal wiring inside SR22 body screwdriver blade width 2 mm 8 3 Appendix on spare parts for SR22 e Desiccant holder with glass window and rubber ring e Desiccant set of 5 bags in air tight bag e Humidity indicator e Levelling feet set of 2 e Static foot e Sun screen with metal ring and thumb screw e SR22 cable with connector specify length in multiples of 5 m e O ring SR22 NOTE Outer dome level and sensor of SR22 cannot be supplied as spare parts In SR22 manual v1506 case of possible damage to the SR22 after repair the instrument must be tested to verify performance within specification limits This is reguired by ISO 9060 Testing involves verification of the directional response after dome thermal sensor and level replacement and verification of the
13. sensitivity due to change in ambient ISO response temperature within an interval of 50 K the temperature of the 9060 interval of 50 K pyranometer body 1990 Tilt response percentage deviation from the sensitivity at 0 tilt horizontal due ISO 0 to 90 at to change in tilt from 0 to 90 at 1000 W m irradiance Tilt 9060 1000 W m response describes changes of the sensitivity due to changes of 1990 the tilt angle of the receiving surface Sensitivity the change in the response of a measuring instrument divided by WMO the corresponding change in the stimulus 1 6 3 Spectral range the spectral range of radiation to which the instrument is Hukseflux sensitive For a normal pyranometer with glass dome s this should be in the 0 3 to 3 x 10 m range Some pyranometers with coloured glass domes have a limited spectral range SR22 manual v1506 38 43 Hukseflux Thermal Sensors 8 9 Appendix on terminology glossary Table 8 9 1 Definitions and references of used terms TERM DEFINITION REFERENCE Solar energy or solar radiation solar energy is the electromagnetic energy emitted by the sun Solar energy is also called solar radiation and shortwave radiation The solar radiation incident on the top of the terrestrial atmosphere is called extra terrestrial solar radiation 97 of which is confined to the spectral range of 290 to 3 000 x 10 m Part of the extra terrestrial solar radiation penetrates the atmo
14. solar spectrum 4 o z a aa 5 2 2 gt Oo E oO O tara 1 6 O 0 oO BS E e jus tui Cc 90 S 2 D Eu gt Oo v 4 North A East South West N ISO secondary N standard N directional response limit zenith angle Figure 2 3 Directional response of a SR22 pyranometer of 4 azimuth angles compared to secondary standard limits SR22 manual v1506 11 43 Hukseflux Thermal Sensors 3 Specifications of SR22 3 1 Specifications of SR22 SR22 is a pyranometer of the highest category in the ISO 9060 classification system secondary standard It measures the solar radiation received by a plane surface from a 180 field of view angle This quantity expressed in W m is called hemispherical solar radiation Working completely passive using a thermopile sensor SR22 generates a small output voltage proportional to this flux It can only be used in combination with a suitable measurement system SR22 has an onboard heater and a temperature sensor Heating the sensor measuring the body temperature and using the correction of the temperature response all contribute to the dependability and accuracy of the measurement However also when not using these features SR22 still complies with the secondary standard requirements The instrument should be used in accordance with the recommended practices of ISO IEC WMO and ASTM Table 3 1 1 Specificat
15. to 5 K h in ambient 2 W m 4 W m 8 W m temperature Non stability change per year 0 8 1 5 3 Non linearity 100 to 1000 W m 0 5 1 3 Directional response 10 W m 20 W m 30 W m Spectral selectivity 350 to 1 500 x 10 m 3 5 10 WMO 300 to 3 000 x 10 m Temperature response interval of 50 K 2 4 8 Tilt response 0 5 2 5 0 to 90 at 1000 W m ADDITI ONAL WMO SPECIFICATI ONS WMO CLASS HIGH OUALITY GOOD QUALITY MODERATE QUALITY WMO achievable accuracy for daily sums 2 5 10 WMO achievable accuracy for hourly sums 3 8 20 WMO achievable accuracy for minute sums not specified not specified not specified WMO resolution 1 W m 5 W m 10 W m smallest detectable change CONFORMITY TESTI NG ISO 9060 individual group group instrument only compliance compliance all specs must comply WMO 7 2 1 The estimated uncertainties are based on the following assumptions a instruments are well maintained correctly aligned and clean b 1 min and 1 h figures are for clear sky irradiances at solar noon c daily exposure values are for clear days at mid latitudes WMO 7 3 2 5 Table 7 5 lists the expected maximum deviation from the true value excluding calibration errors At Hukseflux the expression 1 is used instead of a range of 2 an instrument is subject to conformity testing of its specifications Depending on the classification co
16. used unless this is done separately from the normal measurement by more than 5 times the sensor response time and with a small current only Thermopile sensors are sensitive to the current that is used during open circuit detection The current will generate heat which is measured and will appear as an offset SR22 manual v1506 21 43 Hukseflux Thermal Sensors 6 Making a dependable measurement 6 1 The concept of dependability A measurement with a pyranometer is called dependable if it is reliable i e measuring within required uncertainty limits for most of the time and if problems once they occur can be solved quickly The requirements for a measurement with a pyranometer may be expressed by the user as e required uncertainty of the measurement see following paragraphs e requirements for maintenance and repairs possibilities for maintenance and repair including effort to be made and processing time e arequirement to the expected instrument lifetime until it is no longer feasible to repair It is important to realise that the uncertainty of the measurement is not only determined by the instrument but also by the way it is used See also ISO 9060 note 5 In case of pyranometers the measurement uncertainty as obtained during outdoor measurements is a function of e the instrument class e the calibration procedure uncertainty e the duration of instrument employment under natural sunlight involving t
17. window In case of upwelling E t composed of long wave electromagnetic energy emitted by the earth s surface and by the gases aerosols and clouds of the atmosphere it is also partly absorbed within the atmosphere For a temperature of 300 K 99 99 of the power of the terrestrial radiation has a wavelength longer than 3 000 x 10 m and about 99 per cent longer than 5 000 x 10 m For lower temperatures the spectrum shifts to longer wavelengths ref WMO World measurement standard representing the SI unit of irradiance with an uncertainty Radiometric of less than 0 3 see the WMO Guide to Meteorological Instruments and Reference Methods of Observation 1983 subclause 9 1 3 The reference was adopted by WRR the World Meteorological Organization WMO and has been in effect since 1 July 1980 ref ISO 9060 Albedo ratio of reflected and incoming solar radiation Dimensionless number that varies between 0 and 1 Typical albedo values are lt 0 1 for water from 0 1 for wet soils to 0 5 for dry sand from 0 1 to 0 4 for vegetation up to 0 9 for fresh snow Angle of angle of radiation relative to the sensor measured from normal incidence varies incidence from 0 to 90 Zenith angle angle of incidence of radiation relative to zenith Equals angle of incidence for horizontally mounted instruments Azimuth angle angle of incidence of radiation projected in the plane of the sensor surface Varies from 0 to 360
18. 0 x 10 m while preserving the 180 field of view angle Another function of the dome is that it shields the thermopile sensor from the environment convection rain e a second inner quartz dome For a secondary standard pyranometer two domes are used and not one single dome This construction provides an additional radiation shield resulting in a better thermal equilibrium between the sensor and inner dome compared to using a single dome The effect of having a second dome is a strong reduction of instrument offsets Pyranometers can be manufactured to different specifications and with different levels of verification and characterisation during production The ISO 9060 1990 standard Solar energy specification and classification of instruments for measuring hemispherical solar and direct solar radiation distinguishes between 3 classes secondary standard highest accuracy first class second highest accuracy and second class third highest accuracy From second class to first class and from first class to secondary standard the achievable accuracy improves by a factor 2 SR22 manual v1506 10 43 Hukseflux Thermal Sensors 0 8 0 6 0 4 0 2 relative spectral content response arbitrary units solar radiation pyranometer response 1000 10000 wavelength x 10 9 m Figure 2 2 Spectral response of the pyranometer compared to the solar spectrum SR22 is responsive to the total
19. 2 1 Standards with recommendations for instrument use in solar radiation measurement STANDARDS FOR INSTRUMENT USE FOR HEMISPHERICAL SOLAR RADIATION ISO STANDARD EQUIVALENT WMO ASTM STANDARD ISO TR 9901 1990 ASTM G183 05 WMO No 8 Guide to Solar energy Field Standard Practice for Field Meteorological Instruments pyranometers Recommended Use of Pyranometers and Methods of Observation practice for use Pyrheliometers and UV chapter 7 measurement of Radiometers radiation 7 3 measurement of global and diffuse solar radiation 4 3 General use for sunshine duration measurement According to the World Meteorological Organization WMO 2003 sunshine duration during a given period is defined as the sum of that sub period for which the direct solar irradiance exceeds 120 W m SR22 manual v1506 16 43 Hukseflux Thermal Sensors WMO has approved the pyranometric method to estimate sunshine duration from pyranometer measurements Chapter 8 of the WMO Guide to Instruments and Observation 2008 This implies that a pyranometer may be used in combination with appropriate software to estimate sunshine duration Ask for our application note Table 4 3 1 Standards with recommendations for instrument use in sunshine duration measurement STANDARDS FOR INSTRUMENT USE FOR SUNSHINE DURATION WMO WMO No 8 Guide to Meteorological Instruments and Methods of Observation chapter 8 measurement of sunshine dur
20. Figure 5 2 1 Installation and removal of SR22 s sun screen SR22 manual v1506 19 43 Hukseflux Thermal Sensors 5 3 Electrical connection In order to operate a pyranometer should be connected to a measurement system typically a so called datalogger SR22 is a passive sensor that does not need any power Cables generally act as a source of distortion by picking up capacitive noise We recommend keeping the distance between a datalogger or amplifier and the sensor as short as possible For cable extension see the appendix on this subject Table 5 3 1 The electrical connection of SR22 versions T1 and T2 The heater is not necessarily used The temperature sensor is not necessarily used PIN WIRE SR22 T1 SR22 T2 2 Pt100 10 kQ thermistor 3 Pt100 10 kQ thermistor 6 Pt100 10 kQ thermistor 8 Grey Pt100 10 kQ thermistor 1 heater heater 4 heater heater 9 ground ground 7 White signal signal 5 Green signal signal Note 1 Pt100 s of version T1 may be connected in a 3 wire of 4 wire configuration Note 2 10k thermistors of version T2 are usually connected in a 2 wire configuration Note 3 the heater is not necessarily connected In case it is connected the polarity of the connection is not important Note 4 signal wires are insulated from ground wire and from the sensor body Insulation resistance is tested during production and larger than 1 x 10 Q No
21. The central eguation governing SR22 is E U S Formula 0 1 SR22 s low temperature dependence makes it an ideal candidate for use under very cold and very hot conditions The temperature dependence of every individual instrument is tested and supplied as a second degree polynomial This information can be used for further reduction of temperature dependence during post processing In case the sensitivity is corrected for the instrument body temperature the optional measurement eguation becomes E U So a T b T c Formula 0 2 The temperature coefficients a b and c can be found on the calibration certificate of each instrument SR22 is equipped with an internal temperature sensor This can be either a Pt100 T1 version or a 10 kQ thermistor T2 version as ordered To calculate temperature in degrees Celsius from resistance in Ohms Formula 8 10 1 or 8 10 2 can be used See the dedicated chapter in the appendix of this manual for these eguations SR22 pyranometer uses a state of the art thermopile sensor with black coated surface two quartz domes of the highest quality and an anodised aluminium body The SR22 manual v1506 5 43 Hukseflux Thermal Sensors connector desiccant holder and sun screen fixation are very robust and designed for industrial use All parts are specified for use across SR22 s entire rated operating temperature range In order to improve overall measurement accuracy Hukseflux effectively targeted t
22. Thermal Sensors Hukseflux USER MANUAL SR22 Secondary standard pyranometer with quartz domes extended spectral range Copyright by Hukseflux manual v1506 www hukseflux com info hukseflux com Thermal Sensors f Hukseflux Warning statements A Putting more than 12 Volt across the sensor wiring can lead to permanent damage to the sensor Do not use open circuit detection when measuring N the sensor output SR22 manual v1506 2 43 Hukseflux Thermal Sensors Contents Warning statements Contents List of symbols Introduction 1 AUNE BWNH U PW N N H W Ne 00 00 00 00 09 00 HMO ON NA NN NIIDID AMMNUUUPSPEP AWWWNE EE AUNE FPrFUOAOANOAOUBWNE H O Ordering and checking at delivery Ordering SR22 Included items Quick instrument check Instrument principle and theory Specifications of SR22 Specifications of SR22 Dimensions of SR22 Standards and recommended practices for use Classification standard General use for solar radiation measurement General use for sunshine duration measurement Specific use for outdoor PV system performance testing Specific use in meteorology and climatology Installation of SR22 Site selection and installation Installation of the sun screen Electrical connection Reguirements for data acguisition amplification Making a dependable measurement The concept of dependability Reliability of the measurement Speed of repair and maintenance Uncertainty
23. a is also assumed to be present during daytime Zero offset b response to 5 K h change in ambient temperature ISO 5 K hin ambient Zero offsets are a measure of the stability of the zero point 9060 temperature 1990 Non stability percentage change in sensitivity per year The dependence of ISO change per sensitivity resulting from ageing effects which is a measure of the 9060 year long term stability 1990 Non linearity percentage deviation from the sensitivity at 500 W m due to the ISO 100 to 1000 change in irradiance within the range of 100 W m to 1000 W m 9060 W m Non linearity has an overlap with directional response and 1990 therefore should be handled with care in uncertainty evaluation Directional the range of errors caused by assuming that the normal incidence ISO response sensitivity is valid for all directions when measuring from any 9060 direction a beam radiation whose normal incidence irradiance is 1990 1000 W m Directional response is a measure of the deviations from the ideal cosine behaviour and its azimuthal variation Spectral percentage deviation of the product of spectral absorptance and ISO selectivity 350 spectral transmittance from the corresponding mean within 350 x 9060 to 1500 x 10 m 10 m to 1500 x 10 m and the spectral distribution of irradiance 1990 WMO 300 to Spectral selectivity is a measure of the spectral selectivity of the 3000 x 10 m sensitivity Temperature percentage deviation of the
24. ability but also involves the reaction to problems if the processing time of service and repairs is short this contributes to the dependability Hukseflux pyranometers are designed to allow easy maintenance and repair The main maintenance actions are e replacement of desiccant e replacement of cabling For optimisation of dependability a user should e estimate the expected lifetime of the instrument e design a schedule of regular maintenance e design a schedule of repair or replacement in case of defects When operating multiple instruments in a network Hukseflux recommends keeping procedures simple and having a few spare instruments to act as replacements during service recalibrations and repair 6 4 Uncertainty evaluation The uncertainty of a measurement under outdoor or indoor conditions depends on many factors see paragraph 1 of this chapter It is not possible to give one figure for pyranometer measurement uncertainty The work on uncertainty evaluation is in progress There are several groups around the world participating in standardisation of the method of calculation The effort aims to work according to the guidelines for uncertainty evaluation according to the Guide to Expression of Uncertainty in Measurement or GUM SR22 manual v1506 24 43 Hukseflux Thermal Sensors 6 4 1 Evaluation of measurement uncertainty under outdoor conditions Hukseflux actively participates in the discussions about pyranom
25. able Common options are e Longer cable in multiples of 5 m Specify total cable length e Internal temperature sensor This can be either a Pt100 or a 10 kQ thermistor Specify respectively T1 or T2 e Five silica gel bags in an air thight bag for SR22 desiccant holder Specify order number DCO1 e VUOI ventilation unit 1 2 Included items Arriving at the customer the delivery should include e pyranometer SR22 e sun screen e cable of the length as ordered e calibration certificate matching the instrument serial number e product certificate matching the instrument serial number including temperature response and directional response test e any other options as ordered Please store the certificates in a safe place SR22 manual v1506 7 43 Hukseflux Thermal Sensors 1 3 Quick instrument check A quick test of the instrument can be done by using a simple hand held multimeter and a lamp 1 Check the electrical resistance of the sensor between the green and white wire Use a multimeter at the 1000 Q range Measure the sensor resistance first with one polarity than reverse the polarity Take the average value The typical resistance of the wiring is 0 1 m Typical resistance should be the typical sensor resistance of 100 to 200 Q plus 1 5 Q for the total resistance of two wires back and forth of each 5 m Infinite resistance indicates a broken circuit zero or a low resistance indicates a short circuit
26. anometer properties and calibration uncertainty for sunny clear sky days and well maintained stations without uncertainty loss due to lack of maintenance and due to instrument fouling The table specifies expanded uncertainties with a coverage factor of 2 and confidence level of