Some liquid level controls involve a capacitance sensor, the controller that converts the sensor's voltage to a 4-20ma output, and an I/P transducer to control air flow.

I am looking for the same setup, only would like a device that converts the sensor's voltage to 4-20ma, and then route the 4-20ma to a PLC.

What I want to do is different in that ther will me no controller for scaling, I will have to do all of that in the PLC.

 

See the link below for a custom capacitance probe. You may want to be careful as capacitance is not good if the temperature varies. The dielectric constant of the liquid changes with temperature. Capacitance is excellent with constant temps.

A continuous level sensor with 4-20 out is best if you have temp changes. Custom lengths can be made for most applications.

"http://www.almegcontrols.com/continuous.htm":http://www.almegcontrols.com/continuous.htm

You will also see 4-20 manuals on the opening or main page.

Thanks Bob Hogg
PS Cap. pictures can be emailed direct - not on line yet.

 

Nowadays the capacitive level sensors come with 4-20mA output. I suggest that you can connect the same to the PLC. Please note that they are
powered separately not loop powered.

With best regards,

S. Elavazhagan,
Engineer - I&C,
TCE Consulting Engineers Ltd.,
Bangalore, India.

 

Consider also the use of a pressure sensor for analog level detection. It is cheaper, more rubust and works absolutelly fine.

 

Mr. S Elavazhagan,
I am a student of last yr Electronics Engg working on my project on Water Level Controller with the help of capacitance sensor.Can you be of any help regarding this subject even witrh regards to how the signal conditioning is done after detection?
It will be highly grateful,
thanking you
Deepti
[email protected].



> Nowadays the capacitive level sensors come with 4-20mA output. I suggest that you can connect the same to the PLC. Please note that they are
> powered separately not loop powered.
>
> With best regards,
>
> S. Elavazhagan,
> Engineer - I&C,
> TCE Consulting Engineers Ltd.,
> Bangalore, India.