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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


    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.


  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
  4. John Fields

    John Fields Guest

  5. CFoley1064

    CFoley1064 Guest

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