It is known that when a rotor fault occurs, an induction machine draws an alternative power at twice the rotor frequency. In previous work the authors have shown how to employ this phenomenon in order to detect rotor faults in small inverter fed induction machines. In particular, a rotor fault index has been presented and tested supposing that the AC drive main supply is single phase. Starting from this approach, in the present paper two new rotor fault indexes suitable for three-phase input AC drives will be proposed. Furthermore, their capability to detect early rotor faults in different conditions has been evaluated through an extensive experimental activity. Some results will be presented
