In recent years, with the shortening of the development cycle, model-based development (MBD) has become more important than before. Among them, JMAG-RT provides a plant model to be used for functional requirements and functional verification as shown in Figure 1. The plant model can faithfully reproduce the characteristics of the actual machine from the highly accurate information obtained by the FEA. The accuracy of this plant model depends on the number of calculation points of FEA. The larger the number of calculation points, the higher the accuracy is, but the longer the calculation time is. In addition, saturation occurs which reduces the influence on accuracy with respect to the number of calculation points. In that case, the computation time only becomes long. Therefore, an optimum resolution for determining the number of calculation points is required. This document introduces the method of determining the optimum resolution of the JMAG-RT model while also using the result of the system simulation.