water level control project

Development Boards Arduino
1

hi

in my first project, I devised a circuit that would work as I want my water pump to pump water in Upper tank from ground level tank.It is working as I want but with some strange observation that I can’t explain.

The working is as follows.

  1. It starts manually by a push button connection only if water level in upper tank is below one (receiving)probe in the upper tank.

  2. It continues pumping till the receiving pole touches the water level.

This part is working smoothly over past few months.

  1. The circuit is designed so that the pumping will not start (or stop) if the water level in lower tank is below ( or goes below)certain level in the lower tank.

(The third requirement is just opposite to that of upper tank.)

Few months back I tried with two probes in the lower water tank and it didn’t work.Since I wanted to start filling for our daily need, I followed the following. I kept a plastic bucket,full of water,and inserted same probes in the bucket. If I were to take one probe out of bucket, pumping would stop. This arrangement worked fine, without giving me any protection (as it is designed to give)for water level in the lower tank, since probes were in the bucket!.

I tried again lowering two probes in the lower water tank, where they belong and they still don’t work!

I am unable to see any reason. Since the probes work in the outside bucket, the circuit is correct and working. It seems the environment is causing the problem.

Pumping motor’s earthing is to the body and hence in the water of water tank(?). So immersing probes in the water the probe with voltage gets grounded immediately! Hence no starting of the pump.

Some explanation about my desire for such requirements is in order. With my circuit probes aren’t continuously having voltage 24 x 7! It has voltage only when the pumping is on.

I hope that I have explained my problem well enough so an expert would find an answer for what I am observing.

Thanking you

sureshparanjape

2

It would help if you could post a complete circuit diagram. At the very least describe the water sensor probes plus their associated circuitry, and explain how the probes are supposed to work. Conductivity probes that have a DC voltage between the probe tips are guaranteed to fail after a certain amount of time in the water.

3

Many thanks Mr. Jremington,

Can you guide me to attach circuit drawing or paste circuit drawing in the answer?

I couldn’t get the instruction.

Thanks

sureshparanjape

4

sureshparanjape:

  1. It starts manually by a push button connection only if water level in upper tank is below one (receiving)probe in the upper tank.

  2. It continues pumping till the receiving pole touches the water level.

This part is working smoothly over past few months.

  1. The circuit is designed so that the pumping will not start (or stop) if the water level in lower tank is below ( or goes below)certain level in the lower tank.

I hope that I have explained my problem well enough so an expert would find an answer for what I am observing.

The first thing to do is to describe or post a link to the "probes" being used.

Second … I find your requirements (above) in conflict with the description you then gave, with either 2 probes in the same bucket or 2 probes in the lower tank. I’d have thought you’d have 1 “high water = stop pumping” sensor/pole in the upper tank … and then 1 “low water = stop/don’t start pumping” sensor/pole in the lower tank. So in order for the pump to be on it would seem the upper sensor needs to be dry while the lower sensor needs to be wet. When the upper sensor gets wet OR the lower sensor goes dry, the pump stops (or doesn’t even start).

Yet you have the system working when both sensors are in the same bucket. That sounds like a logic error in your code (depending on how the sensors work). Please post your code as well.

5

I am a newbie also for forum-don’t know how to add a picture or attach a picture to the post.

If someone let me know how to go about it, I would post the circuit.

At present, I can best try my description skill !

I have two probes in each tank- upper and lower.One probe of each tank receives 12 V dc when circuit is active.

Part of the circuit that controls upper tank behavior is using one transistor based switch.Lower one is having just opposite requirement of the upper tank, therefore it uses two transistors as switches, first one converts input from the lower tank to opposite of the input-High becomes low and low becomes High. It then functions just like above tank configuration.

I had read some comments about such level controllers developing problem after some period, rust getting deposited over the probes due to ionization(?). To overcome this difficulty, I have seen a method of making main probe receiving ac voltage,by converting dc voltage to ac.

I put the requirement that there shouldn’t be any dc voltage at probes if pump is not working.This was achieved by putting one relay based push button starter by my friend.The probes receive dc voltage when push button activates the circuit and the system starts functioning.It is therefore semi automatic- starting being governed by the user.

By the way the same friend suggested me yesterday that I should connect a wire to pumps inlet of lower tank and put other end in the bucket where there are two working probes of the lower tank and see if motor works.I tried it this morning and well the motor didn’t work!

So it appears that it is earthing of pumping motor that is causing problem.

Any suggestion would be welcome.I have very limited knowledge but a good friend with good practical knowledge.

My pumping motor sits on the lower water tank, which is what can be described as walls of cement/concrete.Input pipe of the pump lowers in the tank.

6

If you use the “Full Editor” option to post a reply, at the bottom of the screen you will find a tab with the heading “upload attachment”. Follow the directions to post your wiring diagram. Also post a link to the data sheet or the manufacturer’s web page describing the probe you are using.

7

Let’s walk through this 1 piece at a time. You said …

The working is as follows.

  1. It starts manually by a push button connection only if water level in upper tank is below one (receiving)probe in the upper tank.

  2. It continues pumping till the receiving pole touches the water level.

So the probe in the upper/receiving water tank must be "dry" for the pump to be on. When that probe gets "wet" the upper tank is full and pumping stops. OK, this makes sense and seems correct.

Then you say …

  1. The circuit is designed so that the pumping will not start (or stop) if the water level in lower tank is below ( or goes below)certain level in the lower tank.
OK, the lower/source tank must have enough water in it and you know that because the lower/source probe must be "wet" in order for the pump to be on. When that probe is "dry" then pump goes off or doesn't even start. Again this makes sense.

Up to this point it all makes sense and looks correct to me. But then you say …

Few months back I tried with two probes in the lower water tank and it didn’t work

.

Given the logic in steps 1-3 above, you would need to have the probes at different levels, the receiving probe above the water and always dry and the source probe lower and in the water in order for the pump to turn on. If you reversed the probes or had both wet, then I would not expect the pump to ever come on given your logic above. With both probes in the lower tank, you no longer have protection against overflowing the upper/receiving tank.

Then you say …

I kept a plastic bucket,full of water,and inserted same probes in the bucket. If I were to take one probe out of bucket, pumping would stop. This arrangement worked fine, without giving me any protection (as it is designed to give)for water level in the lower tank, since probes were in the bucket!.

This doesn't make much sense given the logic above. One probe (the upper/receiving) must be dry and one probe (lower/source) must be wet in order for the pump to run ... given your logic as stated above. So which is correct ? If the pump ran with both probes wet then it sounds like the upper/receiving probe is broken or it's connection is broken in some fashion. Then when you pull the lower/source probe out of the bucket, the pumping stops ... as it should.

You then say …

I tried again lowering two probes in the lower water tank, where they belong and they still don’t work!

And again I say that doesn't make sense, given your logic above. You said in #1 above that the receiving probe is supposed to be in the upper (destination) tank. Which is correct, #1 or the underlined ?

So I repeat … if you want help, “we” need some details on the probes used … how they are supposed to work and some clarification on how the system is supposed to work … or your testing … as they seem to be in conflict. Your Arduino code would also go a long way to “us” understanding what’s supposed to happen.

8

Many many thanks for taking out time and analyzing my writing (clumsy?). Your analysis of the situation is very correct- pump works only if upper tank probe is dry and lower tank’s probe( both, as I call them receiving)is wet. As I can put it in another way- as long as both probes of the upper tank are in water the pump doesn’t start and as long as both probes in the lower want are in water, the pump can start. In fact if the motor is on and if I take any probe of the lower water tank out, I have noticed that the pumping stops.

As regards your query- " “we” need some details on the probe used…", I have this information to give. These are two simple long wires with copper tips attached to one end and lowered in the each tank; thus in all four- two for each tank.If there is current between probes a transistor switch gets activated.

There is no micro controller in the circuit( my error to put this thread under Arduino folder- sorry- ).

My friend suspects that the earthing of three phase motor could have been compromised over past few years- I would check out and report. If there is no problem there, my solution is to put one small PVC pipe union at the end, near motor, of input that goes down in the tank thereby insulating the lower water tank. However I feel that the earthing should be the culprit.

Again sorry for wrongly opening a link in wrong folder.

sureshparanjape

9

Dear Sir,

Here is my elementary/beginner’s sketch/circuit that I have been using for my project. I am pretty new to this science and you would find many unusual usage of symbols. Please tolerate them, if you can. I hope it conveys all features of the circuit for our project.

The probes that I am using are home made, very crude approximations of the probes that one would find in the market.

I checked the wiring of the three phase motor and to my surprise I found that the neutral/earthing that is from the power source is not connected to the body of the motor. However internet surfing indicated that it is the common practice for a three phase motor.

Presently my motor is working with no probes in the lower water tank. These are placed in a water bucket near the lower tank.It works even if I joined them together.

I am hesitant,for lack of knowledge and for it involves 220 v supply, to connect the neutral/earthing from the power source to the body of the motor. I feel nothing untoward would happen,but …

Thanking you, all who responded to my query, for your patience and guidance.

sureshparanjape

10

That schematic helps a lot ! Frankly I am amazed it works at all but I will guess it all depends on the “un-freshness” of the water. Let me explain. Pure water is actually a very good insulator. It doesn’t conduct electricity very well. If you put your probes in a bucket of pure H2O, the pump would never come on.

But real life water isn’t pure, it’s has salts and other chemicals in it that allow electricty to flow through it. Ocean water is a fairly good conductor, fresh water less so. I’m going to guess that the reason it works in a bucket is because the +probe tips are much closer to the other “sense” probe tips (that are connected to the transistor bases via 2.2K resistors) when in a bucket vs when in the tank. The resistance of the water will vary with the distance through the water, in some fashion I won’t guess at. But the closer the probe tips (+ to “sensing”) are to each other, the less the resistance of the water and the more current will flow … to turn on the appropriate transistor(s).

If you can’t put the probe tips closer together in the tanks (like they are in the bucket) then I would reduce the 2.2K resistors that are attached to the base(s). How much … I can’t say but even 220 ohms is not out of question. Perhaps a 0-5k pot, used as a rheostat, would be the best option, as it would allow you to dial up the resistance that works.

As for the grounding I will say this … as a safety measure any conductive (metal) surface that you could ever come into contact with should be (Earth) grounded. That way if any high voltage ever gets shorted to that surface, it’s also shorted to true Earth ground, and thus unlikely to shock you to death.

11

Thanks for your very quick reply and enlightening me with the practical/theoretical experience.

Two facts puzzles me. The probes in the upper tank works and water quality in both tanks is same.

If I connect the input pipe by a wire to water in the bucket, pump doesn’t work.

I would be very much interested to know shortcomings( which could be many?) of the circuit.

Thanks again sureshparanjape

12

What are the tanks made of ? Can you clarify the following a bit more, the input pipe to what ? And do you mean that you take the bucket where some of the probes are and where the pump has worked, and put a wire into the water in that bucket, with the other end electrically connected to the “input pipe”, that the previously working pump stops working ?

If I connect the input pipe by a wire to water in the bucket, pump doesn’t work.

Is this mystery pipe connected to Earth ground and/or the 12V return ? Is the 12V return connected to Earth ground ? or anything other that what's shown in your schematic above ? And when you use the word "probe", do you mean 1 wire or a pair of wires, what I called the +probe (which is wired to +12V) and "sensing" probe ? How far apart (distance) are the +probe and sensing probe tips when in the tank and when in the bucket ?
13

Dear Sir,Please excuse me for my poor earlier explanations of everything . I hope my explanations this time would be good.

i)Both Water tanks are concrete/cement, roughly about 5 x4x5 (depth).

ii) ‘input pipe’ is for the water pump(inlet for the pump). Pump is located on the top of lower water tank.It has galvanized metal pipe as inlet and outlet.

iii)bucket of water,which has two probes, instead being in the lower water tank, is placed near the lower tank.By creating a continuity between inlet pipe and bucket water I wanted to check whether such continuity would stop the running motor. I connected a wire, one end wrapped around inlet pipe and put the other end in the bucket. This created ‘simulation’ of the inlet pipe being in the lower tank. Since the working motor stops if I put the free end of the wire in the bucket or if the free end is in the bucket, the motor doesn’t start. This simulation indicates that the motor not starting/stop working is caused by the inlet pipe which is necessarily immersed in the lower water tank.

iv)I hope that the above explanation will solve the mystery of ‘mystery’ pipe.It is not connected to anything but to the pumping motor.

v) A probe is just a wire ,one end connected to the board and other end lowered in a tank. The end in the tank has brass end attached to it. One probe receives 12 V and other probe, in the same tank, would receive a current/voltage if there is water between two probes.

vi)The +probe in the upper tank is about three feet below sensing probe;however both probes in the bucket rest at the bottom, about five inch distance between them.

I was watching water level rising in the upper tank while it was getting filled. I was amazed to see motor stopping instant water touching sensing probe!

I am of the opinion that both probes in both tank can be almost at the same height.The upper tanks probes should be near the top while the lower water tank probes should be just above the end (non returned valve)of the inlet (to the motor) pipe.

I hope my this explanation is better than earlier writings.

Many thanks for your patience and sorry for my earlier writings, which wasn’t very clear(I hope this one is!?). This stems out of my poor knowledge.

sureshparanjape