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jibipaul
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Join Date: Nov 2011
Posts: 11

Instrumentation

11/14/2011 1:15 PM

why we are using 4-20 mA in instrumentation
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lyn
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#1

Re: instrumentation

11/14/2011 1:18 PM

Google Answers: 4-20 milliamp circuits

Sounds like homework to me.
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PWSlack
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United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

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#2

Re: Instrumentation

11/15/2011 3:09 AM

Dunno. Ask "we"?

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irelandeng
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Location: Waterford, Ireland
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#5
In reply to #2

Re: Instrumentation

11/17/2011 7:42 PM

LOL

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tonykuphaldt
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Engineering Fields - Instrumentation Engineering - New Member Engineering Fields - Control Engineering - New Member Technical Fields - Technical Writing - New Member Technical Fields - Education - New Member Fans of Old Computers - Apple II -

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#3

Re: Instrumentation

11/15/2011 8:18 AM

4 to 20 milliamp current loops allow the instrument to be powered by the same two wires carrying the measurement signal, which is more cost-effective than providing another pair of wires to convey power. Also, the 4-20 mA loop has a low impedance which helps it reject noise. Voltage signal standards such as 1 to 5 volt or 0 to 10 volts are more susceptible to induced noise.

You are welcome to consult the chapter in my online book for more detailed information:

"Analog Electronic Instrumentation" (Chapter 13) in http://www.openbookproject.net/books/socratic/sinst/book/liii.pdf

- Tony

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Anonymous Poster #1
#4

Re: Instrumentation

11/15/2011 1:17 PM

Because 4-20 MEGA amps would just be silly...

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Anonymous Poster (1); irelandeng (1); lyn (1); PWSlack (1); tonykuphaldt (1)

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