Measurement errors

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Accuracy is an important characteristic of measuring instruments. Measurement errors occur in different ways for various reasons, and when analyzing these reasons, it is necessary first of all to determine their significant impact on the measurement results.

Accuracy is an important characteristic of measuring instruments. Measurement errors occur in different ways for various reasons, and when analyzing these reasons, it is necessary first of all to determine their significant impact on the measurement results.
According to their characteristics, measurement errors are divided into the following types:

Absolute error. This error is described in the units in which the value ((X) is expressed, and in the general case, the measurement result obtained from this measuring instrument is determined by the difference between the values of the measured quantity Ax and the true Xh (in fact, its value is true - X0).
(X=Ax-Xch or (X=Ax-X0
For measurements, the absolute error is:
(U=Un-U0
for measuring instruments
(X \u003d A (-X0,

In addition to the normal operating conditions of measuring instruments, the operating conditions are also determined.
When developing or repairing measuring instruments, their parameters are regulated, calibrated (calibrated) under normal conditions. Measuring instruments should be adjusted so that their errors are minimized in normal use. Therefore, it is important that the measuring instruments deviate from the normal values of the influencing quantities. Therefore, the factors affecting different measuring instruments may be different.
Operating conditions are defined as the range of values that is affected by the error of the measuring instrument. The use of measuring instruments in conditions other than working ones is not allowed.
One of the important features of measuring instruments is the change in the output signal. (For measuring devices, this is called changing the indication of the device).
Variation is the largest difference that can be obtained by re-measuring a quantity without changing the conditions, and is defined as follows.

The concept of accuracy class is used to compare the accuracy of different measuring instruments of the same type, designed to measure the same quantity.
The accuracy class of measuring instruments is a generalized characteristic of a certain type of measuring instruments, reflecting the level of its accuracy, within the main and additional errors, as well as other signs that affect the accuracy of the measuring instrument, determined by

Accuracy classes of digital measuring instruments are determined without taking into account the state of processing for further processing of measurement results.
Typically, measurement instruments use a standardized error value to pre-determine the input error in the result. The mean value of the error is the error related to a given measuring instrument. The error of one or another measuring instrument may be different, and the ratio of regular and random errors may also differ. Information about the margin of error of each measuring instrument and the coefficients of influence will be presented in the passport of the measuring instrument.
Measuring instruments are often divided into tolerance classes. For example, electromechanical display devices use the following standard accuracy class.

It should be noted that the accuracy class is not a direct indicator of the accuracy of measurements made by one or another measuring instrument. The accuracy class generally describes the set of metrological properties of the measuring instrument, but does not unilaterally determine the measurement accuracy, since the measurement accuracy depends on the measurement method and the conditions under which the measurement is performed.
Accuracy classes of measuring instruments are set in standard values in accordance with their requirements. For several measuring instruments designed to measure the same size, or for instruments used to measure different sizes, an accuracy class is assigned to each range or each measured quanti

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