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How do I use this Test Function on a DMM? Answered

 My DMM has a function for a 20mA loopback circuit. It rates 4mA at 5% and 20mA at 100%
So what would I use this test function for?  Instead of using  the Amps test function?

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steveastrouk
steveastrouk

11 years ago

Its used for testing industrial control systems that use what is called a 4-20mA loop. The instrument modulates the current with whatever its reading, and the voltage developed across the instrument powers it.

It is a robust way of reading and driving remote instruments and is very popular.

http://en.wikipedia.org/wiki/Current_loop explains the principles.

Steve

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ricoplace
ricoplace

Answer 11 years ago

steveastrouk,
 Oh, so cool! Thank you so much! I am looking it up on the wikipedia. Thanks for the link.

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NachoMahma
NachoMahma

11 years ago

.  What steveastrouk said plus 4mA should be 0%, not 5%.

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Sandisk1duo
Sandisk1duo

11 years ago

Leds use 20ma, maybe it's used for that?