Sequential or random switching

[Paul2011]

I have a rainwater harvesting system with three tanks each with a separate pump. I will have a pressure vessel and pressure switch to automatically start pumping when water is required. However, I do not want to run all three pumps together but one at a time. I need a switch which will ensure all three pumps are used in roughly equal proportions. It seems to me this could be sequential, switching to each pump in turn or completely random i.e. starting a different pump randomly each time.

Does such a switch exist and if so what is its technical name? Any suggestions - other than changing configuration of tanks and pumps which cannot be done!

thanks

 

[snowhead]

Don't know the cost but this does exactly what you want;

http://www.google.co.uk/url?sa=t&rc...niNhNxhYwe99SXQ&bvm=bv.62922401,d.d2k&cad=rja

 

[snowhead]

Update

120v as you'd expect.


Time Mark Multi-Stage Alternator, B471-120VAC, 60 day warranty | eBay

 

[Paul2011]

Update

120v as you'd expect.


Time Mark Multi-Stage Alternator, B471-120VAC, 60 day warranty | eBay

Thanks. At least I know what I am looking for now. Just need to find one 240v and at a reasonable price.

 

[Paul2011]

Update

120v as you'd expect.


Time Mark Multi-Stage Alternator, B471-120VAC, 60 day warranty | eBay

I have found a 240v version of this, but the cost is almost £200!! I wonder if any forum members can think of more economical solutions

 

[tazz]

I can if your good with a soldering iron

 

[Marvo]

Why have the tanks got 3 pumps? Surely the tanks are linked so they self-level. I'd just use one pump all the time and keep the other two as redundancy in the case of failure.

 

[Paul2011]

Why have the tanks got 3 pumps? Surely the tanks are linked so they self-level. I'd just use one pump all the time and keep the other two as redundancy in the case of failure.

Sorry. Without going into detail the tank/pump configuration has to stay the same so I need an electrical switching solution

 

[Paul2011]

I can if your good with a soldering iron

well I've used one but not an expert! But maybe find someone who is.

 

[tazz]

ok will draw it out for you

 

[Marvo]

I still don't understand why there's 3 different pumps.

 

[Paul2011]

I still don't understand why there's 3 different pumps.

Okay. The tanks have to stay separate and unlinked. One surface mounted pump could be used but that would mean that I have to be sure of the one pump drawing equal amounts of water from the three tanks. I have considered this as an option but on balance I think the three submersible pumps with an electrical switching system is the better solution.

 

[tazz]

Hope you can work this out...each time the contacts are closed on your time switch it latches an on/off function......so sequence is
off / pump1 on / off / pump2 on / off /pump3 on/off / then pump1 on again.......hope this helps

View attachment Pump Sequencer.pdf

 

[Richard]

I'v little experience, but if your prepared to doa bit of research then I imagine a mircocontroller like this might be an option.

Arduino Uno R3 Microcontroller: Amazon.co.uk: Computers & Accessories

 

[Paul2011]

Hope you can work this out...each time the contacts are closed on your time switch it latches an on/off function......so sequence is
off / pump1 on / off / pump2 on / off /pump3 on/off / then pump1 on again.......hope this helps

View attachment 23629

Thanks tazz. Much appreciated.

 

[guest119]

https://www.google.co.uk/search?q=s..._en-GBGB439&gfe_rd=cr&ei=pUUnU6iYIqbR8gfe14Ag

 

[Engineer54]

Okay. The tanks have to stay separate and unlinked. One surface mounted pump could be used but that would mean that I have to be sure of the one pump drawing equal amounts of water from the three tanks. I have considered this as an option but on balance I think the three submersible pumps with an electrical switching system is the better solution.

What Marvo is asking, ...is ''WHY'', because basically it makes no sense??

If the the 3 tanks are linked, they will self level themselves (the larger the linking pipes, the faster the self leveling will be), and only one pump will be required rather than three pumps. Oh, and motorised pumps, be they submersible or otherwise, are very reliable bits of kit today and not something you need to constantly watch over....

 

[Darkwood]

If asked id build a small panel PLC controlled, water level, flow switches and alarm status... Pumps would work as requested if flow switch failed to monitor water flow the pump in question would be locked out and other pump takes over. Alarm would be raised.

A little bit more money but you won't get a call out in the middle of the night saying its flooded because one pump failed.

 

[tazz]

With electronics moving so fast now Darkwood adding features and fail safes ontop of fail safes, does not really add any more cost in development, it seems to be the final sale price where it is bumped up.

 

[Darkwood]

Know what your saying was just referring to the concept of having a design fail-safe set-up is going to cost more than a cheaper sequencing device thats switching existing controls.

Enclosure, Selv - DC power source, door interlock, float level relay etc etc just the basic will ramp cost up and like when i design systems from scratch i do charge for design and commissioning 'if complex' so it soon can mount up although in the OP case id probably russle up the panel without much thinking.