The rain monitor serves as a signal transmitter for determining the start and end of precipitation. It is used as a status indicator or signal transmitter for controlling downstream safety devices (control systems) for protecting windows, ventilation flaps, blinds, awnings, etc. The sensor surface is a capacitor on a glass-coated ceramic. The glass passivation makes the rain monitor highly environmentally resistant, robust, long-term stable, and resistant to aggressive media.
Precipitation that hits the rain monitor and wets the sensor surface changes the capacitance of the surface. This change triggers a switching signal, meaning a wetted sensor surface signals the precipitation status "yes."
To protect against condensation and icing, the sensor surface is heated to an excess temperature of approx. 2 K.
When the sensor surface is wetted, it is regulated to approximately 10 K above the ambient temperature, thus accelerating drying. After drying, the device switches to the "no" precipitation status.
