User`s guide

Chapter 2 __________________________________________________________ Product Overview
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Rain Detector
0105-062
Figure 48 Rain Detector DRD11A
Rain and snow are detected quickly and accurately with Rain Detector
DRD11A. It operates via droplet detection.A special delay circuitry
allows about two-minute interval between raindrops before assuming
an OFF (no rain) position. This enables the sensor to accurately
distinguish between rain cessation and light rain.
DRD11A is positioned at a 30° angle. This design, together with the
internal heating element, ensures that the surface dries quickly, an
essential factor in calculating intensity. The same heating element also
protects the surface from fog and condensed moisture. In addition, the
heating element is activated at low temperatures in order to melt snow,
thus allowing snow detection. Sensor performance is not affected by
reasonable amounts of dirt and dust due to droplet detection.
Due to the heating power requirements, DRD11A is recommended to be
used only at stations equipped with AC power.
The DRD11A sensor set includes the sensor itself, cable, connector,
small signal conditioner card, and installation accessories for the sensor
arm.