Analysis of errors in the measurement of chopped impulses

IEC 60-2 with its new approach to the qualification of industrial measuring systems covers also the case of chopped LI (lightning impulses), with time to chopping down to 500 ns. The paper discusses the procedure for the possible qualification of a reference measuring system in terms of the parameters of the USR, the sources of error and their dependence on the actual waveform: the influence of the shape of the voltage collapse depending upon the way in which the chopping action is obtained is also discussed.