Campbell Scientific SP-LITE Solar Radiation Sensor - Manual (Page 17)

SP-LITE Silicon Pyranometer
13
6. Maintenance
The SP-LITE is an ‘all weather’ instrument and is very stable, but should be
handled with care. It requires little periodic maintenance, apart from cleaning
the sensor surfaces carefully with a soft cloth using water or alcohol.
6.1 Calibration
It is recommended that the SP-LITE is checked, and re-calibrated if necessary,
every two years. The calibration can be checked by running the SP-LITE in
parallel with a reference sensor for at least two sunny days, and then comparing
the daily readings. The reference sensor should either be a higher standard
pyranometer, or an SP-LITE that is kept stored and used solely for this
purpose. If results differ by more than 5 percent, the sensor should be returned
for re-calibration. Please contact Campbell Scientific or your local
representative for further details.
7. Troubleshooting
7.1 Pyranometer produces no apparent output
If your pyranometer does not appear to be working at all, do the following
checks:
• With the SP-LITE disconnected from the datalogger, connect a volt meter
to the white (+) and green (-) wires. The voltage range should be 0-15 mV
for 0-1500 W m
-2
radiation.
• If this appears to produce no results, measure the impedance of the sensor
across the white and green wires. The impedance reading should be close
to 50 Ohms. If it is less than 5 Ohms, a short circuit is indicated. If it is
‘infinite’, the sensor is damaged, or the cable is broken.
7.2 Readings are not as expected
• Under full sunlight the expected radiation value is about 1000 W m -2
.
• Verify that the multiplier parameter in the measurement instruction is
correct for the desired units (e.g., W m -2 , see Section 5 above).
• Check the datalogger program for errors.
If you cannot resolve your problems, please contact Campbell Scientific for
further advice.