Active thermography with electromagnetic excitation, meaning induction and conduction thermography, is a reliable NDE method with a wide range of applications. Over the past years the basics of the electromagnetic excitation, including the influence of the material of the component to be tested and the necessary post-processing algorithms have been studied. In this paper a a study on defect models, including delaminations, the well-known slot and notch type cracks, contact-point and "area of reduced conductivity" type cracks, as well as sub-surface cracks is presented. A detailed parameter study is discussed with parameters like depth, width, length, inductor position, rotation, and inclination.