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Accuracy readings of a Fluke multimeter

Discussion in 'Electronic Basics' started by Jim, Jan 14, 2004.

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  1. Jim

    Jim Guest

    Hi,


    Can anyone explain the accuracy data of a multimeter specification.

    I am looking at a Fluke 170 meter. The accuracy shown for the resistance is
    +/- (0.9%+1) .

    I understand the +/- bit, and I assume the percentage is a percentage of the
    reading but what is the +1 about?

    Any help appreciated.

    Rgds


    Jim
     
  2.  
  3. CFoley1064

    CFoley1064 Guest


    Hi, Jim. The accuracy specification for digital meters is frequently listed as
    +/- percent of reading +/- number of digits or counts. So, your specification
    means that, on that range, the meter is accurate to /- 0.9% of reading +/- 1
    digit or count.

    (By the way, I think the spec on the Fluke 179 and other 170 series meters is
    +/- 0.09% rather than 0.9%. This is a *very* good handheld meter, if a little
    pricey, and just about indestructible under normal use. 0.9% accuracy is
    something you'd expect from one of the generic sub-$30 knockoff meters.)

    Let's say your spec is for DC Volts on a Fluke 179. So, if you read 10.00 VDC,
    you are guaranteed accuracy of +/- 0.9% (+/- 0.09V) +/- 1 count (which would be
    0.01V on that range). That would mean your maximum error would be +/- 0.10V.
    In other words, the actual voltage could be anywhere between 9.9V and 10.1V.

    If your Fluke 179 is rated for +/- 0.09% +/- 1 digit (the correct accuracy
    specification), on a 10.00V reading your guaranteed error would be +/-0.09%
    (0.01V) +/- 1 digit (0.01V), or +/- 0.02V. You're guaranteed that the actual
    voltage is between 9.98V and 10.02V. Big difference.

    Hope this has been of help.

    Good luck
    Chris
     
  4. John Fields

    John Fields Guest

     
  5. CFoley1064

    CFoley1064 Guest

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