Apogee Instruments SU-220 Manual do Proprietário - Página 14
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TROUBLESHOOTING AND CUSTOMER SUPPORT
Independent Verification of Functionality
Apogee SU-100 sensors are self-powered devices and output a voltage signal proportional to incident UV radiation.
A quick and easy check of sensor functionality can be determined using a voltmeter with millivolt resolution.
Connect the positive lead of the voltmeter to the white wire from the sensor and the negative lead (or common) to
the black wire from the sensor. Direct the sensor head toward the sun and verify the sensor provides a signal.
Blocking all UV radiation from the sensor should force the sensor signal to zero.
Compatible Measurement Devices (Dataloggers/Controllers/Meters)
-2
-1
SU-100 UV sensors are calibrated with a standard calibration factor of 5.0 µmol m
s
per mV, yielding a sensitivity
-2
-1
of 0.2 mV per µmol m
s
. Thus, a compatible measurement device (e.g., datalogger or controller) should have
-2
-1
resolution of at least 0.2 mV in order to provide a measurement resolution of 1 µmol m
s
.
An example datalogger program for Campbell Scientific dataloggers can be found on the Apogee webpage at
http://www.apogeeinstruments.com/content/UV-Sensor.CR1.
Cable Length
When the sensor is connected to a measurement device with high input impedance, sensor output signals are not
changed by shortening the cable or splicing on additional cable in the field. Tests have shown that if the input
impedance of the measurements device is greater than 1 mega-ohm there is negligible effect on the calibration,
even after adding up to 100 m of cable. All Apogee sensors use shielded, twisted pair cable to minimize
electromagnetic interference. For best measurements, the shield wire must be connected to an earth ground. This
is particularly important when using the sensor with long lead lengths in electromagnetically noisy environments.
Unit Conversion
-2
-1
SU-100 UV sensors are calibrated in photon flux units of µmol m
s
. It is possible to convert the photon flux value
-2
to energy flux units of W m
. Example of this conversion can be found in the Knowledge Base of the Apogee
website (http://www.apogeeinstruments.com/knowledge-base/; scroll down to UV Sensors section).
Modifying Cable Length
See Apogee webpage for details on how to extend sensor cable length:
(http://www.apogeeinstruments.com/how-to-make-a-weatherproof-cable-splice/).