DANSK DSF/FPREN 62271-110 PDF

This part of IEC 62271 is applicable to a.c. switching devices designed for indoor or outdoor installation, for operation at frequencies of 50 Hz and 60 Hz on systems having voltages above 1 000 V and applied for inductive current switching. The standard is applicable to switching devices (including circuit-breakers in accordance with IEC 62271-100) that are used to switch high-voltage motor currents and shunt reactor currents and also to high-voltage contactors used to switch high-voltage motor currents as covered by IEC 62271-106. For circuit-breakers applied to switch shunt reactor currents at rated voltages according to IEC 62271-1:2016 the requirements related to combined voltage tests across the isolating distance (Tables 3 and 4), are not applicable. Switching unloaded transformers, i.e. breaking transformer magnetizing current, is not considered 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 the switching of transformer magnetizing current using linear components in a test laboratory. Tests conducted using an available transformer, such as a test transformer, will only be valid 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 severe than any other inductive current switching duty. It should be noted that such a duty may produce severe overvoltages within the transformer winding(s) depending on the re-ignition behaviour of the switching device and transformer winding resonance frequencies. NOTE 1 – The switching of tertiary reactors from the high-voltage side of the transformer is not covered by this standard. 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-leg reactor scheme), is discussed in IEC/TR 62271-306.