Measurement uncertainty of fast pulse voltages measurements with capacitive divider

Abstract

Causes of measurement uncertainties might be numerous and as the rule, not all of them can be considered. Two basic types of measurement uncertainty are the type A and the type B. Measurement uncertainty of type A is determined only by method of statistical data processing. A result of this is that measurement uncertainty of type A exists only in case of a measurement repeated several times. Measurement uncertainty of type B is determined by all other methods, except by the statistical method. Measurement uncertainty type B is used regardless if individual or repeated measurements are the issue. The combined measurement uncertainty represents a resultant value in case when a measuring uncertainty originates from two or more different components. The influence of measurement uncertainty of type A and B as well as combined uncertainty during the measuring of fast pulses by using capacitive divider have been considered in the paper. A budget of measurement uncertainty has been formed for that purpose, the one that is characteristic for measuring fast pulses with a capacitive divider. Several types of capacitive dividers have been designed and used (with different types of high-voltage capacitor, low-voltage capacitor and with adjustable resistance) that provide minimization of certain measurement uncertainty budget components. Measuring of pulse voltages under well-controlled laboratory conditions has been performed for each type of capacitive divider. The parameter of these experiments will be pulse rising time (in the ranges of ms, μs, ns). On basis of the obtained results, it is possible to conclude which components of the voltage divider (construction, materials, capacitance, inductivity etc.) influence the measurement uncertainty. The paper provides recommendations for choosing the optimal type of capacitive divider in accordance with minimal measurement uncertainty.