26
Table 6.2.2
Trouble shooting for 00.16131.501000
The sensor does
not give any
signal
Check the electrical resistance of the sensor between the grey
(-
) and white (+) wire. Use a multimeter at the 1000 Ω range. Measure the sensor resistance
first with one polarity, than reverse the polarity. Take the average value. The typical resistance
of the wiring is 0.1 Ω/m. Typical resistance should be the typical sensor resistance of 50 to 150
Ω plus 1.5 Ω for the total resistance of two wires (back and forth) length of the used cable.
Infinite resistance indicates a broken circuit; zero or a low resistance indicates a short circuit.
Check if the sensor reacts to light: put the multimeter at its most sensitive range of DC voltage
measurement, typically the 100 x 10
-3
VDC range or lower. Expose the sensor to strong light
source, for instance a 100 W light bulb at 1 x 10
-1
m distance. The signal should read >
2 x 10
-3
V now. Darken the sensor either by putting something over it or switching off the light.
The instrument voltage output should go down and within one minute approach 0 V. Check the
data acquisition by applying a 1 x 10
-6
V source to it in the 1 x 10
-6
V range. Check the
condition of the connectors (on chassis as well as the cable).
The sensor
signal is
unrealistically
high or low.
Note that night-time signals may be negative due to zero offset a and heating offsets when the
heater is used. The contribution from zero offset a can be down to -5 W/m2, offset due to
heating can be -8 W/m2.
Check if the pyranometer has clean domes.
Check the location of the pyranometer; are there any obstructions that could explain the
measurement result.
Check the orientation / levelling of the pyranometer.
Check if the right calibration factor is entered into the algorithm. Please note that each sensor
has its own individual calibration factor, as documented in its calibration certificate.
Check if the voltage reading is divided by the calibration factor in review of the algorithm.
Check the condition of the wiring at the logger.
Check the cable condition looking for cable breaks. Check the condition of the connectors (on
chassis as well as the cable). Check the range of the data logger; signal can be negative (this
could be out of range) or the amplitude could be out of range. Check the data acquisition by
applying a 1 x 10
-6
V source to it in the
1 x 10
-6
V range. Look at the output. Check if the output is as expected.
Check the data acquisition by short circuiting the data acquisition input with a 100 Ω resistor.
Look at the output. Check if the output is close to 0 W/m2.
The sensor
signal shows
unexpected
variations
Check the presence of strong sources of electromagnetic radiation (radar, radio)
Check the condition of the shielding.
Check the condition of the sensor cable.
Check if the cable is not moving during the measurement
Check the condition of the connectors (on chassis as well as the cable)
The outer dome
shows internal
condensation.
In case there is a minor layer of moisture that is hardly visible: Arrange to send the sensor
back to LAMBRECHT for diagnosis.
The inner dome
shows internal
condensation
Arrange to send the sensor back to LAMBRECHT for diagnosis.
