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I have a digital multimeter and its accuracy for VDC is marked like this:
This multimeter has maximum display of 80000. So in the 80 V range it can show for example 79.999V. 0.03% of 80V is 0.024V - that is clear for me. But what does the The device in question in Digitek DT-80000. |
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The 1 digit means that the least significant digit can be off by +/- 1. In this resolution 1 digit would mean +/- 0.001V. 10 digit means that basically of your 79.999V displayed, it could also be 79.989V (not including the 0,03%!) So basically in your range the 10 digit specification means that +/- 0.03% + 0,01V is your error. For measuring 79.999V it means an absolute maximum error or +/- 0.03%*79.999 + 0.01 = 0.034V. |
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Like Hans says +/-1 digit means that the last digit can be 1 off. +/-10 digits means it can be 10 digits off, or 1 digit in the one but last position. It shows how relative 5 digits (actually 4 3/4) of resolution are: while you get 5 digits, only 4 are significant, the last one is not reliable. This may not look too bad, 10 in 80000 is 0.01%, to be added to the 0.03% basic accuracy. However, while the 0.03% is relative to the measured value, the 10 digits are absolute, and they weigh more if your reading is lower. 10 in 80000 was 0.01%, if your reading is 20000 this error will be 0.05%, or larger than the relative error. |
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