Abstract: The method is based on associating at least two saturation criteria for detecting a saturation phase when said criteria are satisfied simultaneously. It is characterized in that a first saturation criterion (C? sat) takes account of the calculation of an instantaneous prediction error (?(Yk)) which is a function of the difference between the measured secondary current (iS) and the secondary current (îS) predicted with the aid of a mathematical model, and in that a second saturation criterion (C?sat) takes account of the instantaneous algebraic flux (?mes) calculated by integrating the sampled secondary current (Yk), comparing said algebraic flux to a positive threshold (S+, S?+) and to a negative threshold (S?, S??). Said comparison is initialized with exaggerated probabilities of satisfying said second saturation criterion at the start of the measurement, in particular by overestimating (?_rem_high) the absolute value of the remanent flux of the transformer.