Range Selection and Measurement Error Analysis of Multimeter Resistance
Taking a MF-30 multimeter as an example, the center resistance of the Rxl0 block is 250Ω, the center resistance of the Rxl00 block is 2.5kΩ, and the accuracy level is 2.5.
Use R×l0 gear and R×100 gear to measure a 500Ω standard resistance, which gear has a larger measurement error?
1. R×l0 block: the maximum absolute allowable error △R(10)=central resistance×R%=250Ω×(±2.5)%=±6.25Ω.
Measure the 500Ω standard resistance, and the indicated value of the 500Ω standard resistance is between 493.75Ω and 506.25Ω. The maximum relative error is: ±6.25÷500Ω×100%=±1.25%.
2. R×l00 gear: the maximum absolute allowable error △R(100)=central resistance×R%2.5kΩ×(±2.5)%=±62.5Ω.
Measure the 500Ω standard resistance, and the indicated value of the 500Ω standard resistance is between 437.5Ω and 562.5Ω. The maximum relative error is: ±62.5÷500Ω×100%=±10.5%.
Result analysis:
If you choose different resistance ranges, the measurement errors will be quite different, so how can you reduce the measurement errors?
When selecting the gear range, try to make the measured resistance value in the center of the arc length of the range scale to improve the measurement accuracy and reduce the measurement error.
multimeter electric barrier
The range of resistance in the multimeter is very wide, and each range can be used to measure the resistance value from 0 to ∞.
The expression formula of the accuracy of the electric resistance of the multimeter: R%=(△R/central resistance)×100%.
The scale scale of the ohmmeter is a non-linear and uneven inverted scale, which is expressed as a percentage of the arc length of the scale. The internal resistance of each range is equal to the center scale of the arc length of the scale multiplied by the magnification, which is called "center resistance".
When the measured resistance is equal to the center resistance of the selected range, the current flowing in the circuit is half of the full-scale current, and the pointer indicates the center of the scale.
The above are the selection requirements of the electric resistance range of the multimeter, and the error comparison when using the electric resistance of the multimeter to measure resistance. I hope it will be helpful to everyone.
