**6. Conclusions**

In this paper, a method for estimating the sizes and localized losses due to inter-laminar short faults in laminated steel sheets has been developed based on the surface temperature measurement and numerical modeling. This method has been applied to determine the fault parameters on two stacks of electrical steel sheets with an artificial weld contact to represent inter-laminar short circuit fault. Experimental measurement of surface temperature rise using an infrared camera is conducted on two samples with different fault sizes under a DC power supply condition. An inverse modeling technique is used to obtain the best fitting parameter of the fault region from the coupled numerical model. The parameters obtained from the inverse approximation are validated by comparing the measured

temperature rise of the fault region and total loss with the numerical model for different DC current supply conditions. The analysis of the results obtained showed that the material properties of the fault region are closer to prior known material properties of the sample used and the fault size depends on the number of laminations and the length of fault. However, these parameters affect the temperature rise of the fault region. Therefore, the technique developed for obtaining the fault parameters can be generalized for studying inter-laminar short faults in electrical machines. Also, the visual image of the hotspot region can be used for fast detection of inter-laminar short circuit faults in the core of electrical machines.

**Author Contributions:** Conceptualization, O.O.; funding acquisition, A.A.; investigation, O.O.; methodology, O.O. and A.H.; supervision, A.B.; writing—original draft, O.O.; writing—review and editing, A.H., F.M. and A.B. All authors have read and agreed to the published version of the manuscript.

**Funding:** The research leading to these results has received funding from the European Research Council under the European Unions Seventh Framework Programme (FP7/2007-2013) ERC gran<sup>t</sup> agreemen<sup>t</sup> no 339380.

**Conflicts of Interest:** The authors declare no conflict of interest.
