The register of perturbations affecting power systems and their elements are of great importance, as these data provide information for the analysis of these disturbances and subsequent classification. However, there are more information and equipments dedicated to the study of power quality disturbances in low voltage, especially in endpoints such as substations, since the voltage levels that are handled are low and do not represent a high risk for the staff responsible for the measurements. Additionally, studies in medium voltage concerning perturbations (i.e. overvoltages) in the network are not common; therefore, it is necessary to develop tools to perform such studies maintaining the safety of staff and ensuring the less damage as possible on the system. This paper shows the main characteristics and design criteria of the electronic system used as a part of a prototype developed to register the main parameters of the overvoltages in medium voltage networks.