The difference between multimeter grade and accuracy
First, the accuracy level of the multimeter
The accuracy of the multimeter is generally expressed by accuracy, which reflects the size of the basic error of the meter. The higher the accuracy, the smaller the measurement error.
The accuracy of the multimeter is divided into 7 grades: 0.1, 0.2, 0.5, 1.0, 1.5, 2.5, 5.0. In recent years, with the rapid development of the instrument industry, my country has been able to manufacture 0.05-level indicating instruments.
The accuracy level reflects the size of the basic error of the instrument. The accuracy of the domestic MF18 multimeter for measuring DC voltage (DC V), DC current (DC A) and resistance (Ω) is 1.0, which can be used in laboratories.
The Model 500 multimeter, which is still widely used, is a Class 2.5 meter. It should be pointed out that due to the influence of circuits such as voltage dividers, shunts, and rectifiers, the basic errors of each block of the same multimeter are also different.
2. Multimeter grade and accuracy
Are the rating and accuracy of a multimeter the same thing? When calculating the maximum relative error, how to calculate only the accuracy?
The level of measurement data accuracy is called "accuracy level", which is expressed by the percentage of positive and negative errors.
For example, a grade of 2.5 means that its error rate is 2.5%. Each gear of the multimeter often has different accuracy grades. For example, the DC gear and the ohm gear are soil 1.5, and the AC gear may be soil 3.0, which is marked on the dial of the meter.
3. How to verify the accuracy of the multimeter
Use a resistor of known resistance to measure and verify; use a power supply of known voltage to measure and verify.
4. Why is the accuracy of the multimeter called 4 and a half digits or 3 and a half digits?
This is the difference in precision, with a 4 1/2 meter being an order of magnitude more accurate than 3 1/2.
Example: For the value to be measured, a 4.5-digit meter can display a value of 1.9999, so the resolution is 0.0001; but a 3.5-digit meter can only display a value of 1.999, and the resolution is 0.001.
Of course, it also depends on whether such a high precision is required, after all, the price is quite different.
