A new technique for detecting incipient inter-laminar insulation failure of laminated stator cores of large generators is proposed in this paper. The proposed scheme is a low flux induction method that employs a novel probe for core testing. The new probe configuration, which uses magnetic material and is scanned in the wedge depression area, significantly improves the sensitivity of fault detection as well as user convenience compared to existing methods. Experimental results from various test generators tested in factory, field, and lab environments under a number of fault conditions are presented to verify the sensitivity and reliability of the proposed scheme.