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4-20 mA to 2-10 mA conversion

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timbu007

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Dear All,
I have a 4-20 mA current loop configuration. I have been asked to build a 2-10 mA configuration. I was told that by adding a resistance in parallel to it that should solve the problem.But this does not make sense to me.Please correct me if I am wrong. I did add a 2.4k resistor but that did not work.
Please any help is appreciated..
Regards,
Tim
 

alexan_e

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Usually there is a current sense resistor at the output, if you double the value or that resistor it should provide half the current.
If you can provide some kind of schematic it would help.

Alex
 

kak111

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You tried 2.4k resistor, that is too big resistance to shunt half of 20mA.
Normally there is 24V supply for current loop. (Can be even low as 12V)

ie. 24V / 20mA = 1.2 k (max) 12V / 20mA = 600 ohms (max)

(i guess right value is in 100...600 ohm in 24V loop)

You should (or must) check the resistance of receiver.
Measure voltage over receiver with several current values and you
can calculate resistance.

Connect resistor with calculated value parallel to receiver.
Receiver takes now current = Iloop / 2.

Read these ....

Current loop - Wikipedia, the free encyclopedia

http://www.bapihvac.com/CatalogPDFs/I_App_Notes/Understanding_Current_Loops.pdf

http://www.bapihvac.com/content/uploads/2010/07/4-20-mA-Current-Loop-Configurations.pdf

Regards KAK
 
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