Frequency analysis of faulty machines - possibilities and limitations

Mathematical modeling is a basic way to simulate electric machines under various faulty conditions because it is to dangerous and/or to expensive to recognize properties of faulty machines by tests in the field or even on specialized test beds. Nowadays, signature analysis of measurable currents of machine windings is the most permissible way to characterize and to compare various faulty conditions. Most often, spectral analysis is applied, so it really important to predict spectra of faulty machines directly from the mathematical model. This paper discusses a methodology, which enables qualitative and quantitative analysis of faulty machines directly in a frequency domain, focusing on both the advantages and the disadvantages of such approach.