How to connect water level sensor to relay?

[Serhioromano]

I have a sensor which works by passing current through water. I mean it is simply naked wire in the water tank. I use 24VCD. Ground wire is at the bottom of the tank and 2 levels electrodes on different levels.

I had a special water level relay. If I connect those sensors there it works. There is sensitivity adjustment knob on that relay.

My question is. How do I connect that kind of sensors to simple 24VDC industrial coil relay? How do i strengthen current that flow through water so that it is enough for coil to engage?

 

[BobB]

It will not work - have tried it before - use one of these.
http://omron.com.au/products/family/241/download/catalog.html

 

[SilverShotBee]

I had a special water level relay. If I connect those sensors there it works. There is sensitivity adjustment knob on that relay.

Is this a Hawker probe by any chance?

Why do you want to use it without it's own controller? Is there a reason you must use a standard relay? Those type of controllers have their own relays in the controller (usually two NO/NC relays), if you need more relay contacts, why cant you connect the NO/NC to the coil of a standard relay and operate that way?

 

[Serhioromano]

Is this a Hawker probe by any chance?

No it is not. I planned to make electrodes myself.

Why do you want to use it without it's own controller? Is there a reason you must use a standard relay?

i am making video tutorial about relay logic and I want to recreate water level relay logic with a group or simple industrial relays creating logic by wiring. I want to use that kind of sensors for demonstration.

So since standard controller relay can use those sensors, if I recreate it with simple relays I have to give people a hint how to connect those sensors to simple relays.

Of course I can always use other type of censors with contacts in it, but I was hoping I can get a hint may be I can use optocoupler or something and if so, what kind.

 

[Serhioromano]

It will not work - have tried it before - use one of these.
http://omron.com.au/products/family/241/download/catalog.html

This is full controller. I plan to make controller out of simple industrial relays. So I only need to make sensor circuit to engage relay.

I suspect there should be something like optocoupler very sensitive on one side and on the other side I can pass 24V to relay coil.

 

[danatomega]

There's plenty of "water leak sensor circuit" diagrams and how-to instructions on the internet (some not so good) - they mostly all require some electronical circuit to operate.

 

[Serhioromano]

There's plenty of "water leak sensor circuit" diagrams and how-to instructions on the internet (some not so good) - they mostly all require some electronical circuit to operate.

Thank you very much. You gave me a clue what keywords to use for google search. Since English is not may first language, I did not know the terms and my search returned useless data.

Now I've got very simple scheme I am going to try.

http://www.circuitdiagram.org/water-liquid-level-sensor-relay-switch.html

 

[nehpets]

It would be advisable to use AC current as opposed to DC current, otherwise you may get electrolysis occuring between probes.

Steve

 

[Firejo]

I did just what you are doing (except I contained everything in a project box) using a standard NPN transistor. I was using 24VDC with the positive lead in the water and six different wires at different levels. Each wire fed the base of the transistor. If you’re using the ground in the water you’ll need a PNP transistor. The transistor switches the relay on and off. You’ll need to make sure that the rely isn’t drawing more current that the transistor can handle but that’s easy to do.
Having said that, I did this for a project used in a display at Automation Fair several years ago so it wasn’t a long term deal. That turned out to be a good thing because once I got the equipment back the corrosion had pretty much completely covered all of the wires so you’ll need to find a way to prevent the corrosion, which will more than likely involve removing conductivity (making it not work), or you’ll need to clean if off (probably) often.
The next time I created a water display where I needed to know the water level I used a 4-20 pressure sensor and that worked very well (and the resolution was much higher).