This paper presents a fast and efficient fault isolation method in 7-phase electrical machines based on the phase currents projections in the stationary reference frames. The study considers both non incipient faults with 15% to 30% fault severities, and incipient ones whose severities vary 1% to 6%. The noise level effect on the fault isolation is also considered. The fault features are extracted from the transformed currents in the frequency domain. The features are processed with a multi-step classification methodology based on usual techniques (principal component analysis, linear discriminant analysis and support vector machine). The simulation results show that the fault classification under low noise level conditions is effective with an accuracy higher than 98%. However, when the noise level increases, the proposal fails to classify incipient faults.