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This paper presents a novel method to detect rotor faults in salient-pole synchronous machines by exploiting small constructional asymmetries in the machine. In order to unambiguously detect the faults, it is very important to identify a signal that is minimally sensitive to the abnormal operating conditions of the machine but highly sensitive to the fault. This paper shows that certain frequency components such as the 30, 90 Hz in the stator current of a 4-pole 60 Hz salient-pole synchronous machine (SM) are good candidates for detecting rotor faults. The paper presents the physical explanation behind these observed frequency components and shows them to be suitable candidates to detect broken damper bars and inter-turn faults in the field winding.