Yes so this is a startrek soundbite. The issue is getting alerts, and knowing if they have been. One way to get notification of ‘triggers’ is with the use of the Venus, who has 5 digital inputs. But that only notifies me via email, thus for urgent situations it is not a perfect solution.
Using the digital I/O of the Venus for bilges etc is great, so I can tell from far away if the bilge pump went on, and then when it is done it shows ‘situation normal’.
But I also wanted some other way of knowing and also hear/see it immediately when we are on the boat. So looking to all kind of relais systems I was baffled by the high prices. A chat with Daniel Boekel landed me on a relais with 2 contacts ( din-rail ofcourse) Wago 788-312. Here is a picture of a 220V one
And here is the schema.
So you use the input to switch both switches on, while you use one of them to keep the relais on, until you press a reset button. The second switch connection is then used for a light, or buzzer, like here.
Now if you have these automatic whale bilge pumps ( 3 wires) you face the dilemma that the switch closed by the relais, will feed 24V to the bilge pump again, even though it might be done working, so in order to prevent current to go to the test wire of the pump, we drop a diode there. ( like on the side of the schema)
Just a recap of wires
24V -> float. -> A1
Ground -> A2
24V -> ON/(OFF) switch -> 11 . when triggered > 14 -> A1
24V -> 21, when triggered > 24 -> buzzer -> ground