If the fully insulated sensor plate gets wet (e.g. raindrops), then a relay switches on. Unlike rain detectors with a metal sensor, this sensor works capacitively. This means that it also switches when it comes into contact with distilled water (when the rain is completely clean). This means that skylights can be
closed, awnings retracted or only rain can be reported. 2 built-in LEDs indicate the function. The sensitivity is adjustable.