MS IEC 62271-110:2010 - High- Voltage Switchhgear and Controlgear- Part 110 : Inductive load Switching (iec 62271-110:2009, idt)
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This International Standard is applicable to a.c. circuit-breakers designed for indoor or
outdoor installation, for operation at frequencies of 50 Hz and 60 Hz on systems having
voltages above 1000 V and applied for inductive current switching with or without additional
short-circuit current breaking duties. The standard is applicable to 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 [2].
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 CIGRE Technical Brochure 305 [1], 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 circuit-breaker re-ignition behaviour and transformer winding resonance
frequencies.
