8
EE33 Humidity / Temperature Sensor for High Humidity and Chemical Applications
RH [%]
start automatic recovery ARC
heating
time
10 s
cool-
down time
3 min
definable threshold e.g. 99 %
ambient humidity
ambient temperature
interval / 30 min
T [°C]
T [min]
T [min]
Please n
ote:
When heating has ended, the system blocks any subsequent heating for 30 minutes. In
other words, if the ambient humidity remains above the defined set point after the initial heating, the next
heating starts again after 30 minutes.
The following types support the condensation prevention function: T4/T5/T8/T10.
4.1.2 Automatic ReCovery (ARC) against Chemical Pollution
When capacitive humidity sensing elements are exposed to chemical pollution (e.g. detergent residues),
the presence of foreign molecules can distort the measurement reading of the sensor. With the ARC
function foreign molecules can be evaporated from the sensing element by brief and intensive heating.
The start of the ARC function can be triggered as follows:
Manual:
by pressing the pushbutton S3 on the circuit board (see chapter 7.1 “Circuit Board”). A manual
start of the ARC function is recommended when
chemical pollution on the sensing element is expected (cleaning/sterilization)
measurement readings deviate significantly from a calibration reference
Cyclic:
by using EE-PCS, ARC can be configured to start periodically at a certain time interval.
Periodic heating shall be used to minimize drift effects in applications with high chemical pollution.
The ideal cycle time depends on the type of pollution and its concentration and has to be determined
empirically.
heating
time
cool-down
time
freezing
heating 1
heating 2
definable interval time
T [°C]
T [min]
