Abstract: The study describes a method for obtaining weber-ampere characteristics of the electromagnetic AC devices using the method of natural-model tests. For natural-model tests of electrical devices a mathematical model implemented in the software package Labview has been proposed. During the research of the method, measuring of weber-ampere characteristics of the electrical device a toroidal output transformer was carried out. A comparison with the exemplary weber-ampere characteristic was carried out, the characteristics received using the method based on natural-model experiment. It is proposed to assess the degree of difference between these characteristics to use the distance between the two compared characteristics normally to a tangent point created in the analyzed point taken on the exemplary characteristics. The effect of current harmonics measurement error on the metrological performance of the proposed method has been studied.