Rain

Rain sensor with light-dependent reset hysteresis, with inverted switching function

Article No.
52 G197 S22
Application
The sensor recognizes rain or snow as precipitation within a few seconds and transmits the report by means of a potential-free relay contact. This switching output can be used for retransmission to e.g. ventilation or shading installations in automatically controlled greenhouses and buildings. Sensitivity settings are not necessary. It recognizes even light drizzles without giving a false rain signal with light condensation.
Functional description
If the response threshold is exceeded, the installed relay picks up without a delay. 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