Apogee Instruments SP-212 Benutzerhandbuch - Seite 18
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Independent Verification of Functionality
Apogee SP-200 series pyranometers provide an amplified voltage output that is proportional to incident total
shortwave radiation. A quick and easy check of sensor functionality can be determined using a DC power supply
and a voltmeter. Power the sensor with a DC voltage by connecting the positive voltage signal to the red wire from
the sensor and the negative (or common) to the black wire from the sensor. Use the voltmeter to measure across
the white wire (output signal) and black wire. Direct the sensor head toward a light source and verify the sensor
provides a signal. Increase and decrease the distance from the sensor head to the light source to verify that the
signal changes proportionally (decreasing signal with increasing distance and increasing signal with decreasing
distance). Blocking all radiation from the sensor should force the sensor signal to zero.
Compatible Measurement Devices (Dataloggers/Controllers/Meters)
Serial Number Range 0-10516. SP-200 series pyranometers are calibrated with a standard calibration factor of 0.5
-2
W m
per mV (SP-212) or 0.25 W m
-2
m
, respectively. Thus, a compatible measurement device (e.g., datalogger or controller) should have resolution of
at least 2 mV, in order to provide shortwave radiation resolution of 1 W m
Serial Numbers 10517 and above. SP-200 series pyranometers are calibrated with a standard calibration factor of
-2
0.8 W m
per mV (SP-212) or 0.4 W m
-2
W m
, respectively. Thus, a compatible measurement device (e.g., datalogger or controller) should have resolution
of at least 1.25 mV, in order to provide shortwave radiation resolution of 1 W m
Effect of 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 1 mega-ohm or higher then there is negligible effect on the
pyranometer calibration, even after adding up to 100 m of cable. Apogee model SP series pyranometers use
shielded, twisted pair cable, which minimizes electromagnetic interference. This is particularly important for long
lead lengths in electromagnetically noisy environments.
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/).
-2
per mV (SP-215), yielding a sensitivity of 2.0 mV per W m
-2
per mV (SP-215), yielding a sensitivity of 1.25 mV per W m
-2
or 4.0 mV per W
-2
.
-2
-2
.
or 2.5 mV per