Rain

Rain sensor with light detection switching hysteresis, standard relay

Article No.
52 G197
Application
The sensor detects precipitation such as rain or snow within seconds and sends a message by means of a potential-free relay contact. This switching output may be forwarded to, for instance, ventilation or shading systems in automated greenhouses or buildings. Sensitivity settings are not required. It detects even light drizzle, without giving a false rain signal in case of light dew.
Functional description
If the plate resistance drops below the adjustable sensitivity setting, the built-in relay immediately drops out. At the same time the integrated sensor heat-ing switches on. When the sur-face has dried off sufficiently (resistance drops below set value plus hysteresis) the automatic reset delay time starts.This reset time is regulated by an incorporated light sensor which provides for an optimal adjustment to the current weather situation. The reset time is increased from approx. 5 min. to up to 60 min. by darkness or by spell of bad weather. This helps to avoid on the one hand unde-sireable temperature increases in a glass house or on the otherhand e.g. to high switching frequencies of the flap actuating motors. From the moment when the reset time starts, up to the moment when the sensor signals „rain again“, the sensor heating switches back to approx. 25% of its total value. This heating beforehand serves to avoid a rain signal during e.g. fog or dew.
Components