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Hygro and Hygrothermal Transducers (Capacitive) for Air Conditioning Applications (907020)


For measuring relative air humidity and temperature

  • Available in the indoor, wall-mounted, and duct version
  • Compact rod versions with connecting cable or robust terminal head
  • With current and voltage outputs as well as passive temperature output
  • Indoor and wall-mounted version can be delivered with two-line LCD display


  • For versatile air conditioning and ventilation applications


Designed for the most frequently used ventilation and air conditioning applications, these measuring probes are characterized in particular by their easy installation, robust form, and reliable humidity measurement technology.
The relative air humidity is recorded by a humidity-dependent capacitor. The capacitive sensor element consists fundamentally of a carrier plate upon which electrodes are placed with a hygroscopic layer of polymer over the top. This polymer film absorbs or releases water molecules from the medium being measured (air), thereby changing the capacity of the capacitor. A downstream electronic circuit converts the capacity corresponding to air humidity, and produces a standardized current or voltage signal.
The measuring probes are only designed for atmospheric pressure systems and non-aggressive gases. They are non-condensing and guarantee a reliable humidity measurement for each working range. Versions are available with an additional temperature duct for extended application.
The measured values are transferred by way of standardized output signals with 4 to 20 mA, 0 to 1 V, or 0 to 10 V at the subsequent electronics. Some versions are also optionally available with a passive Pt100 temperature output, which rules out costs for extended electronics.
The new indoor and wall-mounted case was specifically designed to meet the requirements of the user with regard to ease of assembly and maintenance, as well as looking to optimize measurement technology.. A separate, removable case bottom section with predefined mounting holes ensure, among other things, very simple installation of the indoor version. The holes are also suitable for flush-mounted socket assembly. The simple but practical sealing system also enables easy opening and closing of the device without requiring a great deal of effort. The robust wall case with increased IP65 humidity protection accounts for this requirement. For example, only a single screw is necessary here to secure the device.
Both new variants can be delivered with a two-line LCD display, which enables the simultaneous display of current humidity and temperature measured values in the range of -30 to +60 (+80) °C depending on the version.