ABSTRACT The present work presents the development of a system of measurement of electric energy consumption. This system shows the consumer the amount of energy consumed and its respective monetary value in real time. The prototype was used in a case study to validate its operation. Data were collected to discuss the results obtained. In order to verify if the results obtained in the prototype were correct, several measurements of energy consumption were made in different residential equipment. The consumption values measured by the prototype were compared with the values obtained by the certified and calibrated energy meter provided by COPEL and were satisfactory.