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Noob multimeter question
2

Noob multimeter question

Noob multimeter question

(OP)
I'm going to pre-apologize for this question, as it's pretty simple:

I have a multimeter that I'm trying to figure out what the accuracy is when measuring small values of ohms (.5-10ohms). The booklet for the meter states:

Range:500.00ohms, Resolution: 0.01 ohms, Accuracy 0.05%+10^3

I don't understand the last part of the accuracy reading. The 0.05% I understand (say 20ohms: 20*.0005 = 0.01ohm, so I could read 19.99 to 20.01) but what does the 10^3 mean?

Thanks for any assistance.

RE: Noob multimeter question

Can you look at a datasheet from the same manufacturer to get a better description?  

Offhand, it looks to be a typo, since most such specifications are usually a percentage, which represents a scaling error, and the measurement noise, which is usually given as "counts."  

So, it would normally read "0.05% +/- 3 counts," or something to that effect.

TTFN

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RE: Noob multimeter question

(OP)
This is for a Fluke Multimeter. They state that its accuracy is supposed to be represented as:

+/-([% of reading] + [number of least significant digits])

Isn't 10^3 = 10,000? I don't understand at all. Maybe it is a typo...

RE: Noob multimeter question

(OP)
On their website the accuracy is listed as:

Accuracy ± (0.05%+2)

The 2 means 2 LSD, so is it accurate to 0.1 ohm then since the range is listed as 500.00?

RE: Noob multimeter question

>On their website the accuracy is listed as:
>Accuracy ± (0.05%+2)
>The 2 means 2 LSD, so is it accurate to 0.1 ohm then since the range is listed as 500.00?

The accuracy depends on the reading.
Let's work through it.
Suppose you are measuring roughly 500 ohms.
0.05% of the reading is 0.25 ohms.
2 LSDs is 0.02 ohms.
The accuracy is ±(0.25 + 0.02) = ±0.27 ohms.

If you are measuring only 50 ohms on this same scale the error is then ±(0.025 + 0.02) = ±0.05 ohms

RE: Noob multimeter question

(OP)
IRStuff: OMG, I am a frikin' tard. The 3 is a reference to a note below that states: Using relative mode (REL delta) to zero residual reading). I was stuck looking at it as engineering notation.

This does not, however resolve everything as the specs seem to be conflicting. The book says 10 LSD and the web says 2 LSD.

Logbook: Thanks for the example, it makes the computation completely clear, but I still have the problem with the two listed specs not matching now.

RE: Noob multimeter question

Fluke using superscripted numbers and parentheses to indicate notes.   THAT! is truly lame.

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: Noob multimeter question

Which meter is it?  

Generally, the stuff on web pages tend to be the BEST possible performance, while the actual manual lists all possible configurations.  You'd need to identify the particular model, the webpage, and a link to the manual for us to get any further insight into the problem.

TTFN

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RE: Noob multimeter question

OK, but their caveat, i.e., the asterisk says "Accuracies are best accuracies for each function" on the summary spec page here: http://us.fluke.com/usen/products/specifications.htm?cs_id=26864(FlukeProducts)&category=HMA(FlukeProducts)

The extended spec: http://assets.fluke.com/datasheets/2153ExtSpecs.pdf shows that 3 of the 8 ranges has that accuracy, but they're not the particular range that you're interested in.

Everything seems consistent to me.

TTFN

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RE: Noob multimeter question

That's really helpful, IR. PLS for you.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Noob multimeter question

(OP)
Thank you IRstuff. I get it now.

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