Kipp & Zonen CNR 4 Instruction Manual
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Kipp & Zonen CNR 4 Instruction Manual

Net radiometer
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CNR 4
Net Radiometer
Instruction Manual

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Summary of Contents for Kipp & Zonen CNR 4

  • Page 1 CNR 4 Net Radiometer Instruction Manual...

  • Page 2: Important User Information

    IMPORTANT USER INFORMATION Reading this entire manual is recommended for full understanding of the use of this product. The exclamation mark within an equilateral triangle is intended to alert the user to the presence of important operating and maintenance instructions in the literature accompanying the instrument. Should you have any comments on this manual we will be pleased to receive them at: Kipp &...

  • Page 3: Declaration Of Conformity

    Kipp & Zonen B.V. Delftechpark 36 2628 XH Delft The Netherlands Declare under our sole responsibility that the product Type: CNR 4 Name: Net-Radiometer To which this declaration relates is in conformity with the following standards Imissions EN 50082-1 Group standard...

  • Page 4: Table Of Contents

    The (optional) CNF 4 connector ..................8     1.1.5 Using the CNR 4 calibration factors ................. 8     1.1.6 Using the CNR 4 measuring Net Radiation ............... 9     1.1.6.1 Measuring Solar radiation with the pyranometer ................9     1.1.6.2 Measuring Far Infrared radiation with the pyrgeometer ..............

  • Page 5: General Information

    4 requires very low maintenance. For optimal results however, proper care must be taken. More about maintenance can be found in chapter 4. Chapter 5 can be consulted if a problem with the CNR 4 is suspected; this chapter addresses trouble shooting.

  • Page 6: Connecting The Cnr 4

    The shield of the cable is twisted together and covered with a black sleeve. If the CNR 4 (rod) is grounded to the mast it is advised not to connect the shielding on the data logger side.
  • Page 7 Reliez à la terre si le radiomètre n'est pas connecté Conectar a tierra si el radiómetro no lo está Figure 1.2 The sensor connections of the CNR 4. The sensor has four mV outputs, 2 for the pyranometers and 2 for the pyrgeometers...

  • Page 8: The Radiometer Temperature Connector (T)

    10 kOhm and is therefore less influenced by cable length but has no compensation for it. The shield of the cable is twisted together and covered with a black sleeve. If the CNR 4 (rod) is grounded to the mast it is advised not to connect the shielding on the data logger side.

  • Page 9: The (Optional) Cnf 4 Connector

    (S) and (T) cables run on both sides of the ventilator to the back of the CNF 4 housing. The extra cover that comes with the CNF 4 slides under the CNR 4 cover. The 4 pins connector on the back of the CNF 4 is shown below. The CNR 4 without CNF 4 is supplied with an extra serial number label.

  • Page 10: Using The Cnr 4 Measuring Net Radiation

    1.1.6.3 Measuring the CNR 4's body temperature The CNR 4 has two temperature sensors built in as standard. The main reason to choose between the Pt-100 or the Thermistor is the connected data logger. Some data loggers have inputs for thermistors some only for thermistors some have both.
  • Page 11 109.35 120.93 98.04 109.73 121.32 98.44 110.12 121.70 98.83 110.51 122.09 99.22 110.90 122.47 99.61 111.28 122.86 Table 1.1 Resistance values versus temperature in °C of the CNR 4's Pt-100. The Pt-100 complies with the class A specifications of DIN.
  • Page 12 Resistance values versus temperature in °C of the CNR 4's thermistor. Relatively small errors occur when the CNR 4 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 real sensor temperature and Pt-100 or thermistor reading is less than 0.5 degree.

  • Page 13: Calculation Of The Albedo For Solar Radiation

    1.1.6.4 Calculation of the albedo for solar radiation The albedo is the ratio of incoming and reflected Solar radiation. It is a figure somewhere between 0 and 1. Typical values are 0.9 for snow, and 0.3 for grassland. To determine albedo, the measured values of the two pyranometers can be used.

  • Page 14: Calculation Of The Net (Total) Radiation

    Where E is the irradiance that is calculated for the pyranometer according to equation 1.1, for the pyrgeometer according to equation 1.2. the terms with T cancel from this equation. CNR 4 Performance under different conditions Below, table 1.3, shows an indication of what you might typically expect to measure under different meteorological conditions.
  • Page 15 Typical graphs for the pyrgeometers   Upper   p yrgeometer,     d ay   w ith   a lterna3ng   c loud   fi elds       p yrgeometer:     U _emf   /   S ensi3vity   [ W/m²]   Temp  ...
  • Page 16 Quality assurance of data Because of the fact that separate sensors are used in the CNR 4, there are possibilities to check the quality of the data by analysing the signals. For this, you can use the measurement results of the temperature, the albedo and the net-solar radiation.

  • Page 17: Cnr 4 Properties

    The robustness of the materials used implies that CNR 4 will not suffer from damage inflicted by birds. Figure 2.1 depicts a drawing of CNR 4. From a spectral point of view, the pyranometer and pyrgeometer are complementary. Together they cover the full spectral range: The pyranometer from 0.3 to 3 microns, and the pyrgeometer from 4.5 to 42 microns.

  • Page 18: Specifications Of The Cnr 4

    Properties of the pyranometer The pyranometer consists of a thermopile sensor and a glass dome both integrated in the CNR 4 body. The thermopile is coated with a black absorbent coating. The paint absorbs the radiation, and converts it to heat. The resulting heat flow causes a temperature difference across the thermopile.

  • Page 19: Specifications Of The Pyranometer

    2.2.1 Specifications of the pyranometer Pyranometers Specification Unit Value (All indicated values are absolute values) Spectral range 300 - 2800 (50% points) Definition Instrument sensitivity within a specific spectral range Sensitivity µV/ W/m² 10 to 20 Definition Calibration factor Impedance 20 to 200, typically 50 Ω...
  • Page 20 Irradiance: W/m² 0 to 2000 Definition Measurement range Non-stability < 1 Definition Maximum change of sensitivity per year, percentage of full scale Spectral selectivity < 3% (350 – 1500 nm spectral interval) Deviation of the product of spectral absorption and spectral Definition transmittance from the corresponding mean within the indicated spectral range...

  • Page 21: Spectral Properties Of The Pyranometer

    2.2.2 Spectral properties of the pyranometer The spectral properties of the pyranometer are mainly determined by the properties of the absorber paint and the glass dome. These are depicted in figure 2.3 Figure 2.3 The spectral sensitivity of the pyranometer in combination with the spectrum of the sun, under a clear sky.
  • Page 22 Figure 2.4 The directional response, or cosine response, of the pyranometer: On the horizontal axis, the zenith angle is shown (0E zenith angle equals 90E angle of incidence). The vertical axis shows the deviation from the ideal cosine behaviour expressed in percents.

  • Page 23: Properties Of The Pyrgeometer

    Far Infrared radiation, that is emitted by the sky or the ground you also need to take the pyrgeometer temperature into account. This temperature is measured by a Pt-100 that is incorporated in the body of CNR 4. The calculation of the Far Infrared irradiance is described in chapter 1.
  • Page 24 Definition Instrument sensitivity within a specific spectral range Sensitivity µV/W/m² 5 to 15 Definition Calibration factor Impedance 20 to 200, typically 50 Ω Definition Typical resistance measured at the output < 18 (95% response) Response time Definition Sensor response time Non-linearity <...

  • Page 25: Spectral Properties Of The Pyrgeometer

    2.3.4 Spectral properties of the pyrgeometer The spectral properties of the pyrgeometer are mainly determined by the properties of the absorber paint and the silicon window. The silicon window is coated on the inside with an interference filter, which blocks the solar radiation.

  • Page 26: Properties Of The Cnf 4 (Optional) Ventilation Unit

    8 … 13.5 VDC Heater 10 W @ 12 VDC (15 Ohm) Weight 0.5 kg (CNR 4 + CNF 4 = 1.35 kg) without cables Operating temperature: -40 to +80 °C There is one major reason for heating and ventilation: avoiding water deposition on the pyrgeometer window and on the pyranometer dome.

  • Page 27: Properties Of The Pt-100 And Thermistor

    Properties of the Pt-100 and thermistor The Pt-100 is a common temperature sensor. Essentially it is a resistor that is temperature dependent. The Pt-100 complies with the specifications of DIN, class A. A table stating the resistance values can be found in chapter 1.1.6.3 Alternatively the thermistor, (nominal value is 10k Ohms at 25 degrees Celsius) can be used.

  • Page 28: Calibration

    There is no primary standard for pyrgeometer measurements. The pyrgeometers in the CNR 4 are calibrated relative to the reference that is present at Kipp & Zonen. In turn this reference has been calibrated against the World Reference at WMO in Davos...

  • Page 29: Installation And Maintenance

    It is suggested that the CNR 4 is mounted at a height of at least 1.5 metres above the surface, to avoid shading effects of the instruments on the soil and to promote spatial averaging of the measurement. If the instrument is H metres above the surface, 99% of the input of the lower sensors comes from a circular area with a radius of 10 H.

  • Page 30: Replacing The Ventilator Filter

    The CNF 4 ventilation unit has a filter that can be checked and if required cleaned or replaced. The cover of the ventilator cover (black part in picture below) can be removed by just pulling it down from the CNR 4. The filter needs to be checked for dust and particles every 6 –...

  • Page 31: Trouble Shooting

    All connections to the CNR 4 are made with connectors and cables that can be separated from the main instrument. Check at all times that these connectors are properly attached and screwed to the body of the CNR 4.

  • Page 32: Testing The Pt-100

    The CNR 4 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 your hand in front of the pyrgeometer.

  • Page 33: Cmb 1 Optional Mounting Bracket

    The CMB 1 mounting bracket is ideal for mounting the CNR 4 to a pole or wall. The stainless steel construction ensures a durable fixation to almost any object. The top U bolts allow rotation of the CNR 4 rod, while the extra screw under the front U bolt allows the rod to tilt.
  • Page 34 Fig 7.2 CMB 1 mounting examples with CNR 4, albedometer and pyranometer...

  • Page 35: Delivery

    If there is damage, a claim should be filed with the carrier immediately. In this case, or if the contents are not complete, your dealer should be notified in order to facilitate the repair or replacement of the instrument. The CNR 4 Net-Radiometer delivery will include the following items: A delivery includes: One CNR 4...

  • Page 36: Recalibration Service

    RECALIBRATION SERVICE Pyranometers, UV-meters, pyrgeometers, Net radiometers & Sunshine duration meters Kipp & Zonen solar radiation measurement instruments comply with the most demanding international standards. In order to maintain the specified performance of these instruments, Kipp & Zonen recommends calibration of their instruments at least every two years.
  • Page 37 Our customer support remains at your disposal for any maintenance or repair, calibration, supplies and spares. Für Servicearbeiten und Kalibrierung, Verbrauchsmaterial und Ersatzteile steht Ihnen unsere Customer Support Abteilung zur Verfügung. Notre service ‘Support Clientèle’ reste à votre entière disposition pour tout problème de maintenance, réparation ou d’étalonnage ainsi que pour les accessoires et pièces de rechange.

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