Interlamination short-circuits can cause major damage to electrical machines. Especially endangered are large turbomachines with high yoke width and correspondingly high interlamination voltages. These generate during operation, at certain interlamination short-circuit contact resistance's, high short-circuit currents and lead in the worst case to "core melting." Generally the stator core for interlamination short-circuits is inspected under application of the high induction method, which often cannot give a satisfactory report on the lamination insulation condition. In particular the large magnetizing expense of the stator core (large voltage and current values of the magnetizing cable, availability of a strong current source) has proved to be disadvantageous. Furthermore, this method permits only a localization of hot spots on the surface of the tooth in the case of an assembled stator winding. All other interlamination short-circuits, especially far more dangerous ones in the slot wall or on the slot bottom respectively, are not accessible with this inspection. Also the interlamination short circuit with low contact resistance generated at the contact point little heat and therewith the low temperature. For these reasons, there is a need to develop a safe measuring method, which enables on one hand all interlamination short-circuits to be registered, and on the other hand a quantitative assessment of the danger of the interlamination short-circuits for the machine. For nearly 20 years a measuring method with lower yoke induction has been used without disadvantages of the high induction method. By this method an interlamination short-circuit is detected with a measuring coil. The signal has been interpreted in terms of current. With this interpretation of the measuring signal it is not possible to take a meaningful consistent quantitative analysis of the interlamination short-circuit. For a correct analysis we introduce a calibration procedure and data processing algorithm. The method with introducing a calibration procedure permits a complete analysis of the lamination insulation, both quantitatively and qualitatively. The analysis of the measuring signal, the mechanism of "core melting" and the comparison of the measuring methods will be treated in detail in this article.