The series-resonant converter (SRC) has been used in several application and it recently became popular for Smart Transformers (STs). In this application, the efficiency and reliability are of paramount importance. Although many papers have addressed the design challenges to improve the converter efficiency, discussions about the reliability are still missing in literature. In this context, this paper presents a design procedure focusing on the efficiency and reliability improvement of the SRC for ST application. To improve the efficiency, losses modeling in all components is carefully carried out. Additionally, Silicon-Carbide (SiC) MOSFETs are used to reduce the conduction and switching losses. The reliability is addressed on the converter design by taking the lifetime of the resonant capacitor and the stress on the main components. Experimental results obtained for the optimized 10 kW series resonant converter has shown an efficiency of 98.61%.