Abstract: A method of detecting a fault in an induction machine having one or more windings arranged to draw current at a supply frequency, the method including: performing a process of judging whether a respective sideband of one or more selected harmonics of the supply frequency exists at a predetermined fault frequency in a signal in the one or more windings; and determining that a fault has occurred if the judgement is positive; wherein in the judging process each of the selected harmonics of the supply frequency is a harmonic frequency of the supply frequency other than the supply frequency itself.

Abstract: A method of detecting a stator fault in a multi-phase current induction machine including the steps of: obtaining a respective frequency spectrum for each of the current phases in the induction machine; deriving, from each frequency spectrum, a value for the ITHD (Inverse current Total Harmonic Distortion) for the respective current phase; calculating an ITHD deviation value corresponding to the maximum deviation for the derived ITHD values; judging whether the calculated ITHD deviation value differs from a reference deviation value; and determining, in response to a positive judgement, that there is a stator fault.

Abstract: A method of detecting a fault in an induction machine having one or more windings arranged to draw current at a supply frequency, the method including: performing a process of judging whether a respective sideband of one or more selected harmonics of the supply frequency exists at a predetermined fault frequency in a signal in the one or more windings; and determining that a fault has occurred if the judgement is positive; wherein in the judging process each of the selected harmonics of the supply frequency is a harmonic frequency of the supply frequency other than the supply frequency itself.