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As above.

I'm confused with the '+xxx" after the percentage. Thanks

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  • \$\begingroup\$ this is not a standard notation as far as I'm aware of. Maybe there's a hint somewhere before or after this table? \$\endgroup\$ Commented Nov 1, 2022 at 13:19

1 Answer 1

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This number typically refers to number of "counts", i.e. the least significant digit in each measurement range.

Say you have a 3.5 digit multimeter, and you are measuring a 100.00000 V voltage source.

The multimeter should then (with 3.5 digits) ideally show 100.0 V.
But with a specification of ±0.05%+3 it may show 100*0.005 = 50 mV off due to the percentage error.
In this case, the percentage error would not even show up on the multimeter due to the low resolution. Although when adding the "counts" specification of 3, it may actually show anything between 099.7 and 100.3 V.

Worth to note is that each count is obviously smaller on a higher resolution multimeter (like 6.5 digit). This also means that the counts specification may be higher on a high end multimeter than on a lower end one. But 5 counts on a 6.5 digit multimeter is much better than 3 counts on a 3.5 digit multimeter.

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  • \$\begingroup\$ I just looked at the manual and it says the meter is 20000 "display count". how would affect the calculation/display? Thanks again \$\endgroup\$
    – mrjayviper
    Commented Nov 1, 2022 at 14:09
  • \$\begingroup\$ 20000 display? would be classed as "4.5 digit multimeter". A \$ \pm (.5\%+10)\$ error tells you that the least-significant digit is more than useless - it even affects the next digit a little. You'll often see that least-sig-digit changing randomly. However, if you're comparing two readings, they both may share much of the 0.5% part of the error spec. \$\endgroup\$
    – glen_geek
    Commented Nov 1, 2022 at 16:48

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