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5.2
Special calibration.
With special calibration is meant that the sensitivity of the sensor
(pyranometer) is used to adjust the gain. This is to obtain for
instance a conversion of 200 W/m
Example:
CM 11 with a sensitivity of 5.14 x 10
irradiance of 2000 W/m
The zero point is set as described above under standard
calibration.
2
For 200 W/m
/ mA the applied voltage to the input to set the gain,
is calculated in the following way:
-6
5.14 x 10
x 2000 = 10,28 mV, and adjust the output to
+4 mA + (2000/200) = 14 mA
This should always be smaller than 20 mA.
An input signal change of 0 to 2000 W/m
of 4 to 14 mA.
With the 500 Ohm resistor this results in a voltage change of 2 to 7
Volt.
Depending on the sensor output it can be better to use a
conversion of 50 or 100 W/m
Of course using the total +16 mA range gives the optimal
resolution on the output.
20
INSTRUCTION MANUAL CT 24
CALIBRATION PROCEDURE
2
per mA.
-6
V / W/m
2
2
gives an output change
2
per mA.
2
and max.
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