Once upon a time… Peter was planning to create a sophisticated duck pond for his ducks. And he thought about Cyber Physical Systems and Internet Of Things and to mix up mechanical engineering and software engineering.
Peter was told not to solve mechanical problems using software – but he didn’t care.
Ok – well – I’m Peter…
The major issue is not to have a 220V pump near to the ducks – because sometimes they like to taste cables and that could become hazardous for them. So I decided to have an extra wellshaft where the pump and the cables are placed.
So I used a 1″ tube that the water runs by gravity downhill to the wellshaft. There I have a valve with a swimmer (and a first part of a problem – that valve is only existing in 1/2″) that closes the outflow if the wellshaft is full. That is the mechanical part of my solution.
The pump is pumping 3.100litres/hour and that means the pump is much faster in pumping away the water than gravity through a 1/2″ pipe. with a swimmer based valve at the end, flows.
And the pump will become damaged if it is pumping without water.
So I need an swimmer switch – an electric one – to stop the pump on empty water…
And this is not enough – because if I would start the pump as soon as the swimmer switch says “i’m under water’ then the pump is that fast – that she would be turned off a second later – so I need a second swimmer switch – near to the valve swimmer and only if both swimmer switches are under water – then the pump is turned on.
Really complex – isn’t it?
If you want to see some Enterprise Architect documentation and some sources – just like the article 🙂