The meaning of the digits on a digital multimeter
There are two principles for determining the display digits of a digital instrument: one is that the digits that can display all digits from 0 to 9 are integer digits; the other is that the value of the fractional digit is based on the highest digit of the maximum displayed value as the numerator, using 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 count value is 2000. This indicates that the meter has 3 integer digits, and the numerator of the fractional digit is l and the denominator is 2, so it is called 3 1/2 Bit, pronounced as "three and a half", its highest bit can only display 0 or 1 (0 is usually not displayed).
The highest digit of a 3 2/3-digit (pronounced "three and two-thirds digit") digital multimeter can only display numbers from 0 to 2, so the maximum display value is ±2999. Under the same circumstances, it is 50% higher than the 3 1/2-digit DMM's limit, which is only ±1999.
It should be pointed out that some people still call the 3 2/3-digit instrument a 3 1/2-digit instrument, but they must indicate that its measurement limit has been extended by 50%. To avoid confusing the two.
3 3/4 digits (pronounced as "three and three quarters.") The highest digit of the digital multimeter can display numbers from 0 to 3, so the maximum display value is ±3999, and its limit is greater than that of a 3 1/2 digit meter Twice as high. There are many advantages to using a 3 3/4-digit digital multimeter to measure the grid voltage. For example, the second highest AC voltage range of an ordinary 3 1/2-digit DMM is 200V. If you want to measure the 220v or 380v grid voltage, you must select The highest AC voltage level (usually 700v~750v level) has a resolution of only 1v. In contrast, the second-highest ACV level of the 3 3/4-digit DMM is 400V, which is most suitable for measuring power frequency grid voltage and does not The measurement range does not exceed the range. Its measurement accuracy is better than the above-mentioned 700V block, and the resolution can be increased 10 times to 0.1v, which is the same as the 700V block resolution of the 4 1/2-digit DMM.
Popular digital multimeters are generally 3 1/2 digit instruments. There are two types of 4 1/2-digit digital multimeters: handheld and desktop. Meters with 5 1/2 digits and above are mostly desktop smart digital multimeters.
