Revisiting no-load parameters in steady-state equivalent circuits for distribution transformers

Abstract

In typical single-phase steady-state equivalent circuits for distribution transformers, a parallel circuit branch is used to represent no-load conditions. Currently, in usual engineering practice and teaching, this branch is composed of a resistance and a reactance connected in a parallel arrangement. However, a series arrangement was once used by some authors for the same branch, naturally using different resistance and reactance values. Besides, a fairly recent teaching reference has been found to refer indirectly to such series arrangement, and it has also been frequently noted that several Electric Machinery students tend to erroneously adopt a series arrangement view for this branch. Although the parallel arrangement is far more common in the literature, it seems that its practical advantages should be more explicitly detailed. This work aims at providing practical justifications for such parallel arrangement to represent this branch, as opposed to a series arrangement.