The meaning of the number of digits on a digital multimeter
There are two principles for determining the display digits of a digital instrument: first, it can display all digits from 0 to 9 as integer digits; The second is that the numerical value of the fractional digit is based on the highest digit in the maximum displayed value as the numerator, and the highest digit at full scale is used as the denominator
For example, the maximum display value of a digital multimeter is ± 1999, and the full scale value is 2000, indicating that the instrument has three integer digits. The numerator of the decimal digit is l, and the denominator is 2, so it is called 3 1/2 digits, pronounced as "three and a half digits". Its highest digit can only display 0 or 1 (0 is usually not displayed).
The highest digit of a 3/3 digit multimeter can only display numbers from 0 to 2, so the maximum displayed value is ± 2999. In the same situation, it is 50% higher than the limit of 3 1/2 bit DMM, which is only ± 1999.
It should be pointed out that some people still refer to the 3 2/3 bit instrument as the 3 1/2 bit instrument, but it must be noted that its limit has been extended by 50% to avoid confusion between the two.
The highest digit of a 3 3 3/4 digit digital multimeter can display numbers from 0 to 3, resulting in a maximum display value of ± 3999, which is twice the limit of a 3 1/2 digit instrument. There are many advantages to using a 3 3 3/4 digit digital multimeter to measure grid voltage. For example, the second highest AC voltage range of a typical 3 1/2 digit DMM is 200V, and to measure grid voltage of 220V or 380V, the highest AC voltage range (usually 700v~750v) must be selected, with a resolution of only 1V. In contrast, the second highest ACV range of a 3 3/4 digit DMM is 400V, which is most suitable for measuring power grid voltage. The frequency grid voltage is neither under range nor over range, and its measurement accuracy is better than the 700V range mentioned above. The resolution can be increased by 10 times, reaching 0.1V, which is the same as the 700V resolution of a 4 1/2-bit DMM.
Universal digital multimeters generally belong to 3 1/2 digit instruments. The 4 1/2 digit multimeter comes in two types: handheld and desktop. Most instruments with 5 1/2 bits and above belong to desktop intelligent digital multimeters.
For example, GMC multimeter products: METRAHit 30M nbsp; The reading of a 6 1/2 high-precision digital multimeter should be ± 1999999 (six and a half digits)
