The rain monitor is designed to act as a sensor detecting the start and end of precipitation. It is used as a status indicator or sensor for controlling downstream safety devices (control units) protecting windows, ventilation flaps, sunblinds, awnings, etc. The sensor area takes the form of a capacitor on glass-coated ceramic. Glass passivation ensures that the rain monitor is extremely environment-resistant as well as robust while offering good long-term stability and resistance to aggressive media.

Mode of Operation

Whenever precipitation strikes the rain monitor and wets the sensor surface, this changes the
capacitance of the surface, so triggering a switching signal, i.e. wetting of the sensor surface
signals the precipitation status “yes”.
To protect the sensor surface from bedewing and icing-up, it is heated to an overtemperature of
approx. 2 K.
When the sensor surface is wetted, it is adjusted to approx. 10 K above the ambient temperature,
so ensuring fast faster drying. Once it has dried, the device switches to the precipitation status “no”.