Campbell CNR4 Bedienerhandbuch PDF herunterladen (Seite 34)

CNR4 Net Radiometer

8.4 Testing the Pt-100

Using a multimeter, measure the resistance between the two opposite wires of

the Pt-100 (gray-yellow, gray-brown, green-yellow, green-brown), and

compare the measured value with the resistance values listed in TABLE 7–2.

The resistance should be above 100 Ω at 0 °C, and the cable resistance should

add about 0.026 Ω per each foot of cable. When in doubt, the thermistor

resistance (temperature) can be checked as well for reference.

9. Maintenance and Recalibration

The CNR4 is weatherproof, and is intended for a continuous outdoor use. The

materials used in the pyranometer and the pyrgeometer are robust and require

little maintenance. For optimal results, however, proper care must be taken.

9.1 Cleaning Windows and Domes

The radiometer readings can be reduced if domes and windows are not clean.

The site operator should check the windows and domes of the CNR4 regularly,

and clean them as needed. Use distilled water or alcohol as cleaning solution,

being careful not to scratch the windows and domes during cleaning.

9.2 Recalibration

For quality assurance of the measured data, the manufacturer recommends the

CNR4 be recalibrated on a regular schedule by an authorized Kipp & Zonen

calibration facility.

The CNR4 should be recalibrated every two years. Alternatively, one can

check the sensor calibration by letting a higher standard run parallel to it over a

two-day period and, then, comparing the results. For comparison of

pyranometers, one should use a clear day. For comparison of pyrgeometers,

one should compare the nighttime results. If the deviations are greater than

6%, the sensor should be recalibrated.

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 replacing the drying cartridge every 6 to

12 months. The three screws holding the white solar shield and the six screws

holding the aluminium base plate need to be removed to access the drying

cartridge, as shown in FIGURE 9-1. Make sure that the black rubber gasket is

put in place properly before the base plate is put back to keep the compartment

sealed. The CNR4 comes with two spare drying cartridges. Additional drying

cartridges, pn 26006, can be purchased from Campbell Scientific.

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Campbell CNR4 Bedienerhandbuch Seite 34