phase resistances of the externally connected load bank. When 9.2%
of electrical asymmetry was periodically introduced into the
generator rotor, the stator current signals were collected. The results
are shown in Fig. 13. From the figure, nothing different can be
observed from the time waveforms of the signals before and after
the electrical asymmetry was introduced. Accordingly, the FIHE
was applied to interpret the signals. The corresponding results are
shown in Fig. 14.
From Fig. 14, it is found that both Id(t) and Iq(t) are dominated by
the shift frequency. The criterion < increases as soon as the electrical
asymmetry occurs and it recovers normal immediately when
the asymmetry is removed. So, it can be said that the criterion < is
also a valid indicator of the electrical fault.