Determination of the air-core reactance of transformers by analytical formulae for different topological configurations and its comparison with an electromagnetic 3D approach

This document describes the determination of the saturated inductance of a transformer, which is the slope of the saturation curve Phi(I) under highly saturated conditions. This parameter, which has a strong impact on the overvoltages when energizing a transformer, has been determined from analytic formulae for different transformer technologies. A comparison with the values derived from an electromagnetic 3D calculation is also given in this paper.