ROTRONIC HC2 - Manual (Page 23)

E-M-HC2 Probes-V1_26
Rotronic AG
Bassersdorf, Switzerland
Document code Unit
HygroClip 2 (HC2) Humidity Temperature
Probes: User Guide
Instruction Manual
Document Type
Page 23 of 31
Document title
© 2009-2013; Rotronic AG E-M-HC2 Probes-V1_26
Analog connection example:
7.5 Hand-held probes used with an indicator
The most common source of error when measuring relative humidity with a hand-held probe is a difference
between the temperature of the probe and the temperature of the environment. At a humidity condition of 50
%RH, a temperature difference of 1
C (1.8 F) typically results in an error of 3 %RH on relative humidity.
When using a humidity probe with a portable indicator, it is good practice to monitor the display for
temperature stability. When moving the probe from one area to another, the probe should be given sufficient
time to equilibrate with the environment to be measured. This time can be shortened, and errors avoided, by
using the probe configuration that fits best for your application.
In extreme situations, condensation may occur on the sensors when the probe is colder than the environment.
As long as the humidity / temperature limits of the humidity sensor are not exceeded, condensation does not
alter the calibration of the sensor. However, the sensor has to dry out before it can provide a valid
measurement.
Non-moving air is an excellent insulator. When there is no air movement, surprising differences in temperature
and humidity can noted over short distances. Air movement at the probe generally results in measurements
that are both faster and more accurate.
E2-01XX-ACT
Voltage
Adapter
HC2 probe
Voltage Source
5…24 VDC
or
5…16 VAC
Controller
(or other)
Cable ended with open wires
2 x analog signal
0…1 VDC