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**Home ⇒ Overview Courses ⇒ Electrical engineering ⇒ Complex numbers ⇒ Measurement error**

## Measurement error

### Display units for meters

With digital measuring devices, the measured value can be clearly read. The more precisely the measurement result is to be displayed, the more digits the display must have.

The number of digits or display range describes the number of individual values. The higher the display scope, the more accurate the display, i.e. the higher the resolution. The following table gives you an overview of the most common displays on the market:

- The most significant digit, which can only have the values 0 or 1, is called a half digit!
- If the digit with the highest significance can only have the values 0 to 4, this digit is referred to as a 3/4 digit.
- Digits that can display all values are called whole digits!

### Calculate the error of the digital multimeter

With digital measuring devices, the possible measurement error is made up of the accuracy error rate and the range error (digit error):

**error limit = ± (accuracy error rate + range error)**

The accuracy error rate is the error in percent in relation to the actual measured value.

The range error (digit error) results from the analog-to-digital conversion and refers to the current display range of the measuring device. The range error is at least 1 digit.

To clarify, the following exercise:

#### Exercise: Calculate the error of the digital multimeter

The measured value shown below is displayed on a digital voltmeter. This is a 3½-digit display. What is the maximum voltage value that can be diplayed if the measuring range is set to 200 V DC?

According to the manufacturer, the accuracy error rate is 0.2% and the range error (digit error) error is 2 digits:

Possible error = ± (0,2% from 100.0 V + 2*0.1 V) = 0.4 V

The displayed measured value can therefore range between 9.6 and 10.4 V.