Experimental and Theoretical Study of Interlaminar Eddy Current Loss in Laminated Cores

Insulation failure between the electrical sheets of electrical machines or transformers might occur due to the burrs formed during the cutting process. Together with welding seams or screws used to hold the stack together, the burrs provide a conducting path for eddy currents. In this paper, equivalent conductivities of the EI core with and without interlaminar contacts are determined using 3D finite element computations and measurements. The core loss of the EI core is measured, and the eddy current loss is segregated from the measurements. Based on the acquired eddy current loss, the equivalent conductivities are determined using an iterative approach. In the case of interlaminar fault at one limb, eddy current loss coefficient increased by 2% and in the case of interlaminar fault at two limbs, eddy current loss coefficient increased by 2.7% compared to the healthy case.