UNE-EN IEC 62271-110:2019

This part of IEC 62271 is applicable to a.c. switching devices designed for indoor or outdoorinstallation, for operation at frequencies of 50 Hz and 60 Hz on systems having voltagesabove 1 000 V and applied for inductive current switching. The standard is applicable toswitching devices (including circuit-breakers in accordance with IEC 62271-100) that are usedto switch high-voltage motor currents and shunt reactor currents and also to high-voltagecontactors used to switch high-voltage motor currents as covered by IEC 62271-106. Forcircuit-breakers applied to switch shunt reactor currents at rated voltages according toIEC 62271-1:2016 the requirements related to combined voltage tests across the isolatingdistance (Tables 3 and 4), are not applicable.Switching unloaded transformers, i.e. breaking transformer magnetizing current, is notconsidered in this standard. The reasons for this are as follows:a) due to the non-linearity of the transformer core, it is not possible to correctly model theswitching of transformer magnetizing current using linear components in a test laboratory.Tests conducted using an available transformer, such as a test transformer, will only bevalid for the transformer tested and cannot be representative for other transformers;b) as detailed in IEC/TR 62271-306, the characteristics of this duty are usually less severethan any other inductive current switching duty. It should be noted that such a duty mayproduce severe overvoltages within the transformer winding(s) depending on there-ignition behaviour of the switching device and transformer winding resonancefrequencies.NOTE 1 The switching of tertiary reactors from the high-voltage side of the transformer is not covered by thisstandard.NOTE 2 The switching of shunt reactors earthed through neutral reactors is not covered by this standard. However,the application of test results according to this standard, on the switching of neutral reactor earthed reactors (4-legreactor scheme), is discussed in IEC/TR 62271-306.