Shown below is an HD2013.3 rain detector from Delta OHM:
The rain detector can be used in an automated control system, e.g. to start a pump immediately when there is rain. It detects the rain status only (on/off of rain) but does not measure the rainfall amount (for this purpose, a rain gauge should be used). The detector detects rain by the wetness of the sensing part (the green color pad in the photo).
There are multiple types of output types available:
- RS484 MODBUS-RTU or proprietary protocol
- Analogue (0/4-20 mA by default or 0-10 V on request)
- Voltage-free normally open contact
The voltage-free normally open contact can be connected to a relay to control other equipment.