Precision notation for voltmeters

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From the technical details of a multimeter:




AC Voltage: - Range and Accuracy: 200mV ± (1.0%+2); 2V ± (0.7%+3); 20 ± (1.0%+3); 200/600V ± (1.2%+3)




What does the notation "± (0.7%+3)" mean? Specifically, what does "+3" mean?










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$endgroup$







  • 3




    $begingroup$
    You wrote it so where did the information come from?
    $endgroup$
    – Andy aka
    Mar 8 at 10:17










  • $begingroup$
    See this similar question and its answers.
    $endgroup$
    – Uwe
    Mar 8 at 11:50

















6












$begingroup$


From the technical details of a multimeter:




AC Voltage: - Range and Accuracy: 200mV ± (1.0%+2); 2V ± (0.7%+3); 20 ± (1.0%+3); 200/600V ± (1.2%+3)




What does the notation "± (0.7%+3)" mean? Specifically, what does "+3" mean?










share|improve this question











$endgroup$







  • 3




    $begingroup$
    You wrote it so where did the information come from?
    $endgroup$
    – Andy aka
    Mar 8 at 10:17










  • $begingroup$
    See this similar question and its answers.
    $endgroup$
    – Uwe
    Mar 8 at 11:50













6












6








6





$begingroup$


From the technical details of a multimeter:




AC Voltage: - Range and Accuracy: 200mV ± (1.0%+2); 2V ± (0.7%+3); 20 ± (1.0%+3); 200/600V ± (1.2%+3)




What does the notation "± (0.7%+3)" mean? Specifically, what does "+3" mean?










share|improve this question











$endgroup$




From the technical details of a multimeter:




AC Voltage: - Range and Accuracy: 200mV ± (1.0%+2); 2V ± (0.7%+3); 20 ± (1.0%+3); 200/600V ± (1.2%+3)




What does the notation "± (0.7%+3)" mean? Specifically, what does "+3" mean?







accuracy voltmeter






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edited Mar 8 at 11:39









SamGibson

11.7k41739




11.7k41739










asked Mar 8 at 10:07









user31264user31264

1311




1311







  • 3




    $begingroup$
    You wrote it so where did the information come from?
    $endgroup$
    – Andy aka
    Mar 8 at 10:17










  • $begingroup$
    See this similar question and its answers.
    $endgroup$
    – Uwe
    Mar 8 at 11:50












  • 3




    $begingroup$
    You wrote it so where did the information come from?
    $endgroup$
    – Andy aka
    Mar 8 at 10:17










  • $begingroup$
    See this similar question and its answers.
    $endgroup$
    – Uwe
    Mar 8 at 11:50







3




3




$begingroup$
You wrote it so where did the information come from?
$endgroup$
– Andy aka
Mar 8 at 10:17




$begingroup$
You wrote it so where did the information come from?
$endgroup$
– Andy aka
Mar 8 at 10:17












$begingroup$
See this similar question and its answers.
$endgroup$
– Uwe
Mar 8 at 11:50




$begingroup$
See this similar question and its answers.
$endgroup$
– Uwe
Mar 8 at 11:50










2 Answers
2






active

oldest

votes


















12












$begingroup$


What does the notation "± (0.7%+3)" mean? Specifically, what does "+3" mean?




The "+3" in that context, is the number of least-significant digits (LSD) on that range, which can be in error. This notation is one of a few "industry standard" ways of specifying measurement accuracy.



The accuracy specification you quoted is from the 2V range of whichever meter is in the question. Therefore using that as an example, the accuracy on a reading on the 2V range is between:



(reading +0.7% +3 LSD) and (reading -0.7% -3 LSD)



I found the Etekcity MSR-A600 meter has the same AC voltage specification as you quoted, so I'll use that one to illustrate LSD a little more. That is a 3.5 digit meter i.e. maximum count = 1999. The maximum count value is important for this next calculation.



For a 3.5 digit meter on the 2V range (actual maximum value shown is 1.999V), the LSD value is 1mV (0.001V).



So the accuracy calculation on that 3.5 digit meter's 2V range, is:



reading ±0.7% ±3mV

(where the 3mV is the 3 LSD, on that 2V range, on a 3.5 digit meter)




  • The value of the LSD will vary on other ranges. For example, on a 3.5 digit meter's 200V range (maximum value shown of 199.9V) the LSD value on that range is 0.1V.


  • The "percentage of reading" value is the gain accuracy; the "number of LSD" value is the offset accuracy. They relate to different parts of the measurement process and so have different units.



  • Some more explanations, for future reference and showing more "worked examples" for different meters:



    1. BK Precision: How to Read Accuracy Specifications


    2. Tektronix (Keithley): Specs: How Can I Apply an Accuracy Specification on a Data Sheet to My Specific Measurement (PDF download)

    3. EE.SE: What does it mean when multimeter accuracy is marked as: ±0,03%+10Digit?






share|improve this answer











$endgroup$




















    3












    $begingroup$

    A bit supplemental to the question, but that spec is incomplete. As the voltage being measured is AC (alternating current), bandwidth limitations apply. As they do to any circuit or oscilloscope.



    I have a shiny new PROSTER VC99 meter. AC accuracy is stated as ±(0.8% + 5). It's cheap. But, that is only officially for frequencies of 40 - 400Hz. Whilst you think of your meter as for measuring the mains voltage (50-60Hz), that's fine. It's alluring though to think of the meter as a kinda substitute for an oscilloscope and use it to measure all sorts of AC voltages. That's wrong, as the metered AC voltage will drop into the higher frequencies. For reference, the VC99 response stays surprisingly flat till 4kHz (tested with function generator and oscilloscope). At 40kHz, it's quickly rolled off to only 15% of the true peak to peak.



    So the moral of this answer is: stick it into your wall sockets by all means, but make sure to read the full spec if you're going to stick it into your HI-FI or radar installation.






    share|improve this answer









    $endgroup$












    • $begingroup$
      Good point. The meter I used as an example in my answer (which I found using a search for the same specification given in the question) doesn't list the frequency range for which the specification applies, in its HTML webpage. However its full manual lists similar frequency limitations to your example in its accuracy specification: "40Hz ~ 400Hz, sine wave RMS (average response)."
      $endgroup$
      – SamGibson
      Mar 8 at 15:34












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    2 Answers
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    12












    $begingroup$


    What does the notation "± (0.7%+3)" mean? Specifically, what does "+3" mean?




    The "+3" in that context, is the number of least-significant digits (LSD) on that range, which can be in error. This notation is one of a few "industry standard" ways of specifying measurement accuracy.



    The accuracy specification you quoted is from the 2V range of whichever meter is in the question. Therefore using that as an example, the accuracy on a reading on the 2V range is between:



    (reading +0.7% +3 LSD) and (reading -0.7% -3 LSD)



    I found the Etekcity MSR-A600 meter has the same AC voltage specification as you quoted, so I'll use that one to illustrate LSD a little more. That is a 3.5 digit meter i.e. maximum count = 1999. The maximum count value is important for this next calculation.



    For a 3.5 digit meter on the 2V range (actual maximum value shown is 1.999V), the LSD value is 1mV (0.001V).



    So the accuracy calculation on that 3.5 digit meter's 2V range, is:



    reading ±0.7% ±3mV

    (where the 3mV is the 3 LSD, on that 2V range, on a 3.5 digit meter)




    • The value of the LSD will vary on other ranges. For example, on a 3.5 digit meter's 200V range (maximum value shown of 199.9V) the LSD value on that range is 0.1V.


    • The "percentage of reading" value is the gain accuracy; the "number of LSD" value is the offset accuracy. They relate to different parts of the measurement process and so have different units.



    • Some more explanations, for future reference and showing more "worked examples" for different meters:



      1. BK Precision: How to Read Accuracy Specifications


      2. Tektronix (Keithley): Specs: How Can I Apply an Accuracy Specification on a Data Sheet to My Specific Measurement (PDF download)

      3. EE.SE: What does it mean when multimeter accuracy is marked as: ±0,03%+10Digit?






    share|improve this answer











    $endgroup$

















      12












      $begingroup$


      What does the notation "± (0.7%+3)" mean? Specifically, what does "+3" mean?




      The "+3" in that context, is the number of least-significant digits (LSD) on that range, which can be in error. This notation is one of a few "industry standard" ways of specifying measurement accuracy.



      The accuracy specification you quoted is from the 2V range of whichever meter is in the question. Therefore using that as an example, the accuracy on a reading on the 2V range is between:



      (reading +0.7% +3 LSD) and (reading -0.7% -3 LSD)



      I found the Etekcity MSR-A600 meter has the same AC voltage specification as you quoted, so I'll use that one to illustrate LSD a little more. That is a 3.5 digit meter i.e. maximum count = 1999. The maximum count value is important for this next calculation.



      For a 3.5 digit meter on the 2V range (actual maximum value shown is 1.999V), the LSD value is 1mV (0.001V).



      So the accuracy calculation on that 3.5 digit meter's 2V range, is:



      reading ±0.7% ±3mV

      (where the 3mV is the 3 LSD, on that 2V range, on a 3.5 digit meter)




      • The value of the LSD will vary on other ranges. For example, on a 3.5 digit meter's 200V range (maximum value shown of 199.9V) the LSD value on that range is 0.1V.


      • The "percentage of reading" value is the gain accuracy; the "number of LSD" value is the offset accuracy. They relate to different parts of the measurement process and so have different units.



      • Some more explanations, for future reference and showing more "worked examples" for different meters:



        1. BK Precision: How to Read Accuracy Specifications


        2. Tektronix (Keithley): Specs: How Can I Apply an Accuracy Specification on a Data Sheet to My Specific Measurement (PDF download)

        3. EE.SE: What does it mean when multimeter accuracy is marked as: ±0,03%+10Digit?






      share|improve this answer











      $endgroup$















        12












        12








        12





        $begingroup$


        What does the notation "± (0.7%+3)" mean? Specifically, what does "+3" mean?




        The "+3" in that context, is the number of least-significant digits (LSD) on that range, which can be in error. This notation is one of a few "industry standard" ways of specifying measurement accuracy.



        The accuracy specification you quoted is from the 2V range of whichever meter is in the question. Therefore using that as an example, the accuracy on a reading on the 2V range is between:



        (reading +0.7% +3 LSD) and (reading -0.7% -3 LSD)



        I found the Etekcity MSR-A600 meter has the same AC voltage specification as you quoted, so I'll use that one to illustrate LSD a little more. That is a 3.5 digit meter i.e. maximum count = 1999. The maximum count value is important for this next calculation.



        For a 3.5 digit meter on the 2V range (actual maximum value shown is 1.999V), the LSD value is 1mV (0.001V).



        So the accuracy calculation on that 3.5 digit meter's 2V range, is:



        reading ±0.7% ±3mV

        (where the 3mV is the 3 LSD, on that 2V range, on a 3.5 digit meter)




        • The value of the LSD will vary on other ranges. For example, on a 3.5 digit meter's 200V range (maximum value shown of 199.9V) the LSD value on that range is 0.1V.


        • The "percentage of reading" value is the gain accuracy; the "number of LSD" value is the offset accuracy. They relate to different parts of the measurement process and so have different units.



        • Some more explanations, for future reference and showing more "worked examples" for different meters:



          1. BK Precision: How to Read Accuracy Specifications


          2. Tektronix (Keithley): Specs: How Can I Apply an Accuracy Specification on a Data Sheet to My Specific Measurement (PDF download)

          3. EE.SE: What does it mean when multimeter accuracy is marked as: ±0,03%+10Digit?






        share|improve this answer











        $endgroup$




        What does the notation "± (0.7%+3)" mean? Specifically, what does "+3" mean?




        The "+3" in that context, is the number of least-significant digits (LSD) on that range, which can be in error. This notation is one of a few "industry standard" ways of specifying measurement accuracy.



        The accuracy specification you quoted is from the 2V range of whichever meter is in the question. Therefore using that as an example, the accuracy on a reading on the 2V range is between:



        (reading +0.7% +3 LSD) and (reading -0.7% -3 LSD)



        I found the Etekcity MSR-A600 meter has the same AC voltage specification as you quoted, so I'll use that one to illustrate LSD a little more. That is a 3.5 digit meter i.e. maximum count = 1999. The maximum count value is important for this next calculation.



        For a 3.5 digit meter on the 2V range (actual maximum value shown is 1.999V), the LSD value is 1mV (0.001V).



        So the accuracy calculation on that 3.5 digit meter's 2V range, is:



        reading ±0.7% ±3mV

        (where the 3mV is the 3 LSD, on that 2V range, on a 3.5 digit meter)




        • The value of the LSD will vary on other ranges. For example, on a 3.5 digit meter's 200V range (maximum value shown of 199.9V) the LSD value on that range is 0.1V.


        • The "percentage of reading" value is the gain accuracy; the "number of LSD" value is the offset accuracy. They relate to different parts of the measurement process and so have different units.



        • Some more explanations, for future reference and showing more "worked examples" for different meters:



          1. BK Precision: How to Read Accuracy Specifications


          2. Tektronix (Keithley): Specs: How Can I Apply an Accuracy Specification on a Data Sheet to My Specific Measurement (PDF download)

          3. EE.SE: What does it mean when multimeter accuracy is marked as: ±0,03%+10Digit?







        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited Mar 8 at 18:02

























        answered Mar 8 at 11:37









        SamGibsonSamGibson

        11.7k41739




        11.7k41739























            3












            $begingroup$

            A bit supplemental to the question, but that spec is incomplete. As the voltage being measured is AC (alternating current), bandwidth limitations apply. As they do to any circuit or oscilloscope.



            I have a shiny new PROSTER VC99 meter. AC accuracy is stated as ±(0.8% + 5). It's cheap. But, that is only officially for frequencies of 40 - 400Hz. Whilst you think of your meter as for measuring the mains voltage (50-60Hz), that's fine. It's alluring though to think of the meter as a kinda substitute for an oscilloscope and use it to measure all sorts of AC voltages. That's wrong, as the metered AC voltage will drop into the higher frequencies. For reference, the VC99 response stays surprisingly flat till 4kHz (tested with function generator and oscilloscope). At 40kHz, it's quickly rolled off to only 15% of the true peak to peak.



            So the moral of this answer is: stick it into your wall sockets by all means, but make sure to read the full spec if you're going to stick it into your HI-FI or radar installation.






            share|improve this answer









            $endgroup$












            • $begingroup$
              Good point. The meter I used as an example in my answer (which I found using a search for the same specification given in the question) doesn't list the frequency range for which the specification applies, in its HTML webpage. However its full manual lists similar frequency limitations to your example in its accuracy specification: "40Hz ~ 400Hz, sine wave RMS (average response)."
              $endgroup$
              – SamGibson
              Mar 8 at 15:34
















            3












            $begingroup$

            A bit supplemental to the question, but that spec is incomplete. As the voltage being measured is AC (alternating current), bandwidth limitations apply. As they do to any circuit or oscilloscope.



            I have a shiny new PROSTER VC99 meter. AC accuracy is stated as ±(0.8% + 5). It's cheap. But, that is only officially for frequencies of 40 - 400Hz. Whilst you think of your meter as for measuring the mains voltage (50-60Hz), that's fine. It's alluring though to think of the meter as a kinda substitute for an oscilloscope and use it to measure all sorts of AC voltages. That's wrong, as the metered AC voltage will drop into the higher frequencies. For reference, the VC99 response stays surprisingly flat till 4kHz (tested with function generator and oscilloscope). At 40kHz, it's quickly rolled off to only 15% of the true peak to peak.



            So the moral of this answer is: stick it into your wall sockets by all means, but make sure to read the full spec if you're going to stick it into your HI-FI or radar installation.






            share|improve this answer









            $endgroup$












            • $begingroup$
              Good point. The meter I used as an example in my answer (which I found using a search for the same specification given in the question) doesn't list the frequency range for which the specification applies, in its HTML webpage. However its full manual lists similar frequency limitations to your example in its accuracy specification: "40Hz ~ 400Hz, sine wave RMS (average response)."
              $endgroup$
              – SamGibson
              Mar 8 at 15:34














            3












            3








            3





            $begingroup$

            A bit supplemental to the question, but that spec is incomplete. As the voltage being measured is AC (alternating current), bandwidth limitations apply. As they do to any circuit or oscilloscope.



            I have a shiny new PROSTER VC99 meter. AC accuracy is stated as ±(0.8% + 5). It's cheap. But, that is only officially for frequencies of 40 - 400Hz. Whilst you think of your meter as for measuring the mains voltage (50-60Hz), that's fine. It's alluring though to think of the meter as a kinda substitute for an oscilloscope and use it to measure all sorts of AC voltages. That's wrong, as the metered AC voltage will drop into the higher frequencies. For reference, the VC99 response stays surprisingly flat till 4kHz (tested with function generator and oscilloscope). At 40kHz, it's quickly rolled off to only 15% of the true peak to peak.



            So the moral of this answer is: stick it into your wall sockets by all means, but make sure to read the full spec if you're going to stick it into your HI-FI or radar installation.






            share|improve this answer









            $endgroup$



            A bit supplemental to the question, but that spec is incomplete. As the voltage being measured is AC (alternating current), bandwidth limitations apply. As they do to any circuit or oscilloscope.



            I have a shiny new PROSTER VC99 meter. AC accuracy is stated as ±(0.8% + 5). It's cheap. But, that is only officially for frequencies of 40 - 400Hz. Whilst you think of your meter as for measuring the mains voltage (50-60Hz), that's fine. It's alluring though to think of the meter as a kinda substitute for an oscilloscope and use it to measure all sorts of AC voltages. That's wrong, as the metered AC voltage will drop into the higher frequencies. For reference, the VC99 response stays surprisingly flat till 4kHz (tested with function generator and oscilloscope). At 40kHz, it's quickly rolled off to only 15% of the true peak to peak.



            So the moral of this answer is: stick it into your wall sockets by all means, but make sure to read the full spec if you're going to stick it into your HI-FI or radar installation.







            share|improve this answer












            share|improve this answer



            share|improve this answer










            answered Mar 8 at 13:25









            Paul UszakPaul Uszak

            3,55021843




            3,55021843











            • $begingroup$
              Good point. The meter I used as an example in my answer (which I found using a search for the same specification given in the question) doesn't list the frequency range for which the specification applies, in its HTML webpage. However its full manual lists similar frequency limitations to your example in its accuracy specification: "40Hz ~ 400Hz, sine wave RMS (average response)."
              $endgroup$
              – SamGibson
              Mar 8 at 15:34

















            • $begingroup$
              Good point. The meter I used as an example in my answer (which I found using a search for the same specification given in the question) doesn't list the frequency range for which the specification applies, in its HTML webpage. However its full manual lists similar frequency limitations to your example in its accuracy specification: "40Hz ~ 400Hz, sine wave RMS (average response)."
              $endgroup$
              – SamGibson
              Mar 8 at 15:34
















            $begingroup$
            Good point. The meter I used as an example in my answer (which I found using a search for the same specification given in the question) doesn't list the frequency range for which the specification applies, in its HTML webpage. However its full manual lists similar frequency limitations to your example in its accuracy specification: "40Hz ~ 400Hz, sine wave RMS (average response)."
            $endgroup$
            – SamGibson
            Mar 8 at 15:34





            $begingroup$
            Good point. The meter I used as an example in my answer (which I found using a search for the same specification given in the question) doesn't list the frequency range for which the specification applies, in its HTML webpage. However its full manual lists similar frequency limitations to your example in its accuracy specification: "40Hz ~ 400Hz, sine wave RMS (average response)."
            $endgroup$
            – SamGibson
            Mar 8 at 15:34


















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