Determination of Transient Inrush Currents in Power Transformers Due to Out-of-Phase Switching Occurrences

This paper describes a basic method to determine the crest value of the transient inrush currents flowing in power transformer windings resulting either from imperfect synchronizing procedures or from erroneous switching operations. The currents which flow under these unusual conditions are similar in magnitude and envelope to through-short circuit faults and may, in some cases, exceed the currents which flow through transformer windings during three-phase faults on their terminals.