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| [Sloved] Percent of range, how is it calculated? |
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| ballsystemlord:
Hello, I was reading some specs for DMMs and instead of the typical xx% + xxDigits, I came upon xx% + xx% of range. So if the range is 1000.00V, and I'm measuring 1V, and the accuracy is 0.1% + 0.01% of the range, then I could get a reading of up to 101.001V?! (1V*1.001%)+(1000(range)*0.01%) == 11.001V And that's assuming I'm using only the portion of the range after the period. If not, then 1V could become: (1*1.001)+(100000*0.01) == 1,001.001V!!! Now I suspect I'm making a mistake somewhere, please point me in the right direction. Thanks! |
| Fungus:
I assume you mean when measuring AC voltage. Many TRMS converters are inaccurate at the low end of their ranges. That's why we have auto-ranging meters - to switch to a lower range on demand and avoid these problems. :) |
| ballsystemlord:
No, not AC. This is the DC range. |
| mwb1100:
You’ve got a decimal point in the wrong place. 0.01% of the range would be: (1000V * 0.0001) = 0.1 |
| ballsystemlord:
Which if we took the above datasheet picture and applied that for 1V at the 1V range, we'd get ((1*1.01)+(1*0.00005)) = 1.01005. Or the reading could be off by as much as 1% even though the meter's accuracy is 0.01% in the 1V range... Which means that absolute accuracy specs are a bit misleading? |
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