Interlaminar Insulation Faults Detection and Quality Assessment of Magnetic Cores Using Flux Injection Probe

Interlaminar faults between laminations of the magnetic cores increase core losses and could cause major damage to electrical machines. A system has been developed to detect an interlaminar fault between the laminations of the magnetic cores by means of the flux injection probe (FIP). Experimental work was carried out to calibrate the measuring system and qualify its accuracy over a wide measurement range. Application of a prototype FIP to quality assessment of transformer laminations was investigated in two stages: 1) inspection of stack of laminations with known interlaminar faults applied by artificial shorts and 2) inspection of stack of laminations with unknown quality. The experimental results show that the developed system is capable of detecting an interlaminar fault between as few as two laminations.