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Need 4-20mA converted to fiber optics

Need 4-20mA converted to fiber optics

Need 4-20mA converted to fiber optics

I have a 4-20mA pressure transducer in a well and the cable is run several hundred feet in the ground.  

We have had problems with lightening and are looking to covert the signal to fiber to isolate it from our DDC.  
anyone know a converter that does this?

We also need power isolators which I don't know much about.


RE: Need 4-20mA converted to fiber optics


will also look into a galvanic isolator and / or surge arrestor  

RE: Need 4-20mA converted to fiber optics

The purpose of the powered Isolator would be more than likely due to the distance from the source to the reciever while also providing isolation of the two areas.  If you take into account voltage drop for the wire a powered isolator will help but may be required to be repeated based on the distance traveled.  The isolator can provide an intrinically safe signal from a single or dual channel isolator repeated from the hazardous location to the safe location such as the model 9160's from Stahl.  www.rstahl.com can also provide information on the products that can help with this application.


RE: Need 4-20mA converted to fiber optics

ScottyUK's solution is the best in my humble opinion provided you have power available at both ends. FO cable is immune to lightning unless it gets a direct hit of course.

RE: Need 4-20mA converted to fiber optics

Weed Instruments.. I took them out of the dark ages with a new micro design for their flagship product.

dubbed:  Is there a question here?  A specific question?
I see the sketch what is your specific question?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Need 4-20mA converted to fiber optics

I don't understand the purpose of the relay, or the 2nd battery for that matter.
Your transmitter only draws 20 mA so a battery will last a long time.
You will also need to supply the FO converter.
Perhaps just one battery with a small solar panel.
Another option with a well that only changes slowly is to just sample the level for a few seconds every hour that way you could run on a couple of small dry batteries without a charger.

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