The paper presents an advanced investigation method based on numerical computational fluid dynamics. This calculation allows researches and engineers to understand cycloaliphatic polymeric thermoset epoxy resin behavior during casting process from the fluid dynamics, heat transfer and curing (solidification) exothermal chemical reaction phenomenon point of view. Method is presented on an example of outdoor current and voltage sensor. Results generated by the numerical simulation of the epoxy resin casting process have helped to reduce both product development time and costs, improve the production processes and to improve performance and service life of outdoor epoxy resin encapsulated power product.