Detailed Explanation of Indicators and Characteristics of Digital Multimeters
The so‑called 3‑1/2‑digit digital multimeter can display values from 0000 to 1999. Its most‑significant digit can only show 0 or 1. The digit "3" means the units, tens and hundreds digits can display numbers from 0 to 9; the fraction "1/2" indicates the thousands digit can only show 0 or 1. It is read as "three‑and‑a‑half digits". Typical examples include Huayi MY6, Uni‑T UT54 and Victor VC890D.
The display digits of digital multimeters generally range from 3‑1/2 digits to 8‑1/2 digits.
There are two rules for determining the display digits of a digital instrument: first, the full digits refer to positions that can display all numerals from 0 to 9; second, the numerator of the fractional digit corresponds to the highest digit of the maximum reading. For a full‑scale count of 2000, the instrument has three full digits and a fractional digit with numerator 1 and denominator 2, hence designated as 3‑1/2 digits (read as three‑and‑a‑half digits). Its highest digit can only show 0 or 1 (0 is normally blanked).
A 3‑2/3‑digit digital multimeter (read as three‑and‑two‑thirds digits) has a highest digit capable of displaying 0‑2, giving a maximum reading of ±2999. Under identical conditions, its measuring range is 50 % higher than that of a 3‑1/2‑digit multimeter, which is especially valuable for measuring 380 V AC voltage.
For instance, when measuring mains voltage, an ordinary 3‑1/2‑digit multimeter can only show 0 or 1 on its highest digit. To measure 220 V or 380 V mains voltage, only three digits are available, yielding a resolution of merely 1 V. By contrast, a 3‑3/4‑digit multimeter allows the highest digit to show 0‑3, enabling four‑digit readings with 0.1 V resolution - the same resolution as a 4‑1/2‑digit multimeter.
Popular consumer‑grade digital multimeters are mostly handheld 3‑1/2‑digit models. 4‑1/2‑digit and 5‑1/2‑digit (below 6‑digit) multimeters are available in both handheld and benchtop versions. Models of 6‑1/2 digits and above are mostly benchtop digital multimeters.
