AS IEC-60060-2-2018 pdf download.High-voltage test techniques Part 2: Measuring System.
All measurements are to some degree imperfect. A Measuring System will be influenced by various quantities (e.g. temperature, proximity of earthed or energised structures, interference etc.). It will generally be found that when a measurement is repeated several times there will be a spread in the results (when the requirements of this part of IEC 60 are met this spread will be small). When a measurement is repeated a large number of times, most of the results will be close to a central value and this central value will tend to a constant value as the number of measurements is Increased.
Many high-voltage tests permit only a single measurement. Others require several measurements, e.g. 10 as in clause 6 of this part of IEC 60. A single measurement may give any value In the likely distribution. The possible differences between a single value (or the mean of a small number of m.asur.m.nts) and th. mean of the distribution of all possible values gives a random contributeon of uncertainty.
This annex provides procedures to deal with any number of repetitions of a measurement.
In most measurements, th. overall uncertakity will result from a combination of several contributions which ar classif led into two categories according to the method used to evaluate their numerical values LII’.
H.2.1 Systematic contributions (Type B 1J)
Systematic contributions are those which are not evaluated statistically but are estimated by other means. Some examples are:
— the uncertainty of the calibration of the Measuring System (or its components), stated in the calibration certificate;
— th. drift in the valu, of th. scale factor of the Measuring System (e.g. ageing);
— the use of a Measuring System under constant conditions which are different from those of th. calibration (..g. difler•nt temperature);
— the resolution of each instrument.
Once a Measuring System (or a component) has been calibrated and is then used in a test, the uncertainty of the calibration is treated as one of the systematic contributions in the estimation of the uncertainty of the test result.
H .2.1,1 Systematic contributions (rectangular)
It Is assumed that these systematic contributions have a rectangular distribution, that is, any measured value between the estimated limits (sa. where a is the semi-range value) is assumed to be equally probable.AS IEC-60060-2 pdf download.