Multimeter display digits and accuracy
The display digits of a digital multimeter are usually 3 1/2 digits to 8 1/2 digits. There are two principles for determining the number of display digits of a digital instrument: one is that the number of digits that can display all numbers from 0 to 9 is an integer number; the other is that the value of the fractional digit is based on the highest digit of the maximum displayed value. is the numerator, and the count value when using the full scale is 2000. This shows that the instrument has 3 integer digits, and the numerator of the fractional digit is 1 and the denominator is 2, so it is called 3 1/2 digits, 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 displayed value is ±2999. Under the same circumstances, it is 50% higher than the measurement limit of a 3 1/2-digit digital multimeter, which is especially valuable when measuring 380V AC voltage.
Display digits and accuracy are the two most basic and important indicators of a multimeter. The two are closely related. Generally speaking, the higher the number of digits displayed by a multimeter, the higher the accuracy, and vice versa. However, because the measurement principles and quality standards of each manufacturer are different, some multimeters have high accuracy while others have poor accuracy at the same digit. For example: For the same 41/2 multimeter, some models have an accuracy as high as 0.025%, while others have an accuracy of only 0.8%. There are two ways to display the number of digits: counting display and digit display. The counting display is the actual expression of the range of digits displayed by the multimeter. However, due to people's habits and the convenience of traditional naming, it is generally expressed in digit display.
For example: a 3000-digit count display means that the multimeter's maximum display value can reach 3999, while a 1000-digit count display can only reach 1999. When measuring 220VAC voltage, it can be clearly seen that the 3000-digit display has one more decimal place than the 1000-digit display: like this The resolution is one order of magnitude higher, which will play a greater role in the debugging and testing of highly sensitive microelectrical signals. At the same time, the counting display and the digit display can be converted: first calculate how many zeros there are in the counting display digit, then use the previous number as the denominator of the fraction, and then subtract 1 from the number to become the numerator, which becomes the numerator. show. For example: 3000-digit count, the number of digits is 32/3 digits. The existing product handheld multimeter has reached 500,000 digit display.
Digital multimeters are classified according to the range conversion method and can be divided into three types: manual range (MAN RANGZ), automatic range (AUTO RANGZ), and automatic/manual range (AUTO/MAN RANGZ).
According to different functions, uses and prices, digital multimeters can be roughly divided into 9 categories: low-end digital multimeters (also known as popular digital multimeters), mid-range digital multimeters, medium/high-end digital multimeters, digital/analog hybrid meters, digital /Instruments with dual display of analog diagrams and multi-purpose oscilloscopes (integrating the kinetic energy of digital multimeters, digital storage oscilloscopes, etc.).
