Which of the multimeters has the smallest error when measuring the same voltage in different ranges?
I have a multimeter on hand. When using different ranges of this multimeter to measure the same voltage, and choosing different accuracy levels and ranges, which one produces the smallest error? Let's take a look at the results through an example measurement.
Multimeter voltage measurement error
Choose different ranges of the same multimeter to measure the same voltage and see which one produces a larger error.
Taking the MF-30 multimeter as an example, the selected accuracy is level 2.5, and the selected gears are 100V and 25V, used to measure a 23V standard voltage.
Measurement results:
1. The maximum absolute allowable error of 100V block: X (100) = ±2.5% × 100V = ±2.5V.
2. The maximum absolute allowable error for 25V gear: △X(25)=±2.5%×25V=±0.625V.
It can be seen from the measurement results: Use the 100V gear to measure the 23V standard voltage, and the value on the multimeter is between 20.5V-25.5V. Use the 25V gear to measure the 23V standard voltage, and the value on the multimeter is between 22.375V-23.625V.
△X (100) is greater than △X (25), that is, the error measured in the 100V block is larger than the error measured in the 25V block, and it is not just a tiny bit larger, but almost 4 digits larger.
Measurement recommendations:
When a multimeter measures different voltages, the errors produced by different measurement ranges are different. When the measured signal value is satisfied, it is recommended to select a gear with a small range, which can improve the accuracy of the measurement.
The error of a multimeter measuring different voltages in the same range
Take an MF-30 multimeter as an example. Its accuracy is 2.5. Use the 100V gear to measure a standard voltage of 20V and 80V. Choose which gear has the smallest error.
Measurement error analysis:
1. Maximum relative error: △A% = maximum absolute error △X/measured standard voltage adjustment × 100%, maximum absolute error at 100V block △X (100) = ±2.5% × 100V = ±2.5V.
2. At 20V, the indication value is between 17.5V-22.5V. The maximum relative error is: A(20)%=(±2.5V/20V)×100%=±12.5%.
3. At 80V, the indication value is between 77.5V-82.5V. The maximum relative error is: A(80)%=±(2.5V/80V)×100%=±3.1%.
Comparing the maximum relative errors of the measured voltages of 20V and 80V, you will find that the former has a much larger error than the latter.
Summary: Use the same range of a multimeter to measure two different voltages. The closer to the full scale value, the higher the accuracy. When measuring voltage, the measured voltage should be indicated above 2/3 of the multimeter's range to reduce measurement errors.
