Contents
What component of the DMM error is the largest?
Understanding Digital Multimeter (DMM) specifications
- Accuracy. This is the largest allowable error that your DMM occurs under specific operating conditions.
- Resolution. This is the smallest increment of change a DMM can detect and display.
- Range.
- Precision.
- Display Digits.
- Display Counts.
What is the uncertainty of a multimeter?
A reading of 1.0V on the 30 volt scale will have an uncertainty of 0.6V. For a digital multimeter (DMM), accuracy is usually specified as a percent of the reading, not the full scale reading. So a meter with a specification of 1% of the reading will read an actual value of 100.0V as something between 99.0V and 101.0V.
How do you find the uncertainty of resistance?
This % uncertainty is the same for the slope and its reciprocal, so you can use it for the % uncertainty of R. For example, if the slope is 0.339 mA/volt, and the uncertainty of the slope (twice the standard error) is ±0.001 mA/volt, then the % uncertainty is 0.3%. So, the resistance is: R = 1/slope = 2.95 kΩ ± 0.3%.
How does temperature affect the accuracy of a DMM?
Thus the indicated reading should be within 205µV of the actual value. As with many other electronic items, temperature can have a significant effect on the measurement accuracy of a DMM. Many precision or high accuracy digital multimeters have a temperature coefficient contained within the specification.
Digits and counts give us an idea of the resolution of a DMM. They are not directly related to accuracy. It is a common misconception that digits and counts are the accuracies of a DMM. How are accuracy and resolution related in DMM measurements?
What should you consider when choosing a DMM?
Accuracy and resolution are one of the key specifications to consider when choosing the right digital multimeter (DMM) for your measurements. Figure 3 shows how accuracy relates to the resolution on a measurement scale.
What is the function setting on a DMM?
The Function setting on a VOM or DMM is usually a dial that selects among the basic functions of the instrument: measurements of Volts, Ohms, Amps or on occasion other features. Watch out: be sure to select the proper function for the type of measurement being made.