Introduction to the Resolution of Digital Multimeters
The voltage value corresponding to the last word on the lowest voltage range of a digital multimeter is called resolution, which reflects the sensitivity of the instrument. The resolution of digital instruments increases with the number of displayed digits. The highest resolution indicators that a digital multimeter with different digits can achieve are different.
The resolution index of a digital multimeter can also be displayed using resolution. Resolution refers to the percentage of the minimum number (excluding zero) that the instrument can display to the maximum number.
It should be pointed out that resolution and accuracy belong to two different concepts. The former characterizes the "sensitivity" of the instrument, that is, the ability to "recognize" small voltages; The latter reflects the "accuracy" of the measurement, that is, the degree of consistency between the measurement results and the true value. The two are not necessarily related, so they cannot be confused, let alone mistakenly assume that resolution (or resolution) is similar to accuracy, which depends on the comprehensive error and quantization error of the internal A/D converter and functional converter of the instrument. From a measurement perspective, resolution is the "virtual" indicator (independent of measurement error), while accuracy is the "real" indicator (which determines the size of measurement error). Therefore, increasing the number of display digits arbitrarily to improve the resolution of the instrument is not feasible.
Operating procedures
1. Before use, one should be familiar with the various functions of the multimeter, and correctly select the gear, range, and probe socket based on the measured object.
2. When the size of the measured data is unknown, the range switch should be set to the maximum value first, and then switched from a large range to a small range, so that the instrument pointer indicates more than half of the full scale.
3. When measuring resistance, after selecting the appropriate magnification range, touch the two probes to make the pointer point at the zero position. If the pointer deviates from the zero position, the "zero adjustment" knob should be adjusted to reset the pointer to zero to ensure accurate measurement results. If zero adjustment is not possible or the digital display meter emits a low voltage alarm, it should be checked in a timely manner.
4. When measuring the resistance of a certain circuit, the power supply of the tested circuit must be cut off and live measurement is not allowed.
5. When using a multimeter for measurement, attention should be paid to the safety of personnel and instrument equipment. During the test, it is not allowed to touch the metal part of the probe with hands, and it is not allowed to switch gears with electricity to ensure accurate measurement and avoid accidents such as electric shock and burning of the instrument.
