Modeling of the energization of a power transformer in a 110 kV network and its validation by on site tests. Description of ferroresonance phenomena involved and means to avoid them.

This document presents the energization of a transformer in a 110 kV Distribution Network. It shows that high discrepancies in the circuit-breaker poles closing times may lead to high overvoltages, which have been confirmed by on site tests. Phenomena involved are ferroresonance ones, after the energization of the transformer, when phases A and C saturate while the breaker pole remains open on phase B during 17 ms. Recommendations in order to avoid these overvoltages are given in this paper.