Product manual

Model HC2S3 Temperature and Relative Humidity Probe
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3. Verify the green power wire is connected to the 12V, SW12V, or 5V
terminal. When SW12V is used with a CR10X datalogger, verify the
SW 12V CTRL is jumpered to the Control Port specified in the program.
Cables longer than 3 m (10') should be powered by the 12V, rather than
the 5V terminal.
A voltmeter can be used to check the output voltage for temperature and
relative humidity on the brown and white wires respectively (temperature
°C = mV * 0.1 – 40.0; relative humidity % = mV * 0.1).
Symptom: Incorrect temperature or relative humidity
1. Verify the multiplier and offset parameters are correct for the desired
units (Table 5-1) and temperature range.
2. Default settings are listed in Appendix A, which include the setting
“Limit humidity output to 100%”. This setting is “disabled” for probes
purchased through CSI. Accuracy of the humidity measurement over
temperature is shown in the graph in Section 2.2. For example, at -20°C
the accuracy is ±2.3%, so a reading of 102.3% at 100% humidity is within
the accuracy specification. Programs created by Short Cut set humidity
values >100% and <103% to 100%. Humidity values >103% are left
unchanged to indicate a problem with the probe or measurement.
9. References
Goff, J. A. and S. Gratch, 1946: Low-pressure properties of water from -160°
to 212°F, Trans. Amer. Soc. Heat. Vent. Eng., 51, 125-164.
Lowe, P. R., 1977: An approximating polynomial for the computation of
saturation vapor pressure, J. Appl. Meteor., 16, 100-103.
Weiss, A., 1977: Algorithms for the calculation of moist air properties on a
hand calculator, Amer. Soc. Ag. Eng., 20, 1133-1136.