This paper describes a distributed digital system under development at CEPEL, integrating measurement, control and protection of an electric power substation. In this system, the signals are digitalized and transmitted to the inputs of digital processors connected by a local network. This network, together with the application software developed, allows synchronization of the sampling processes at different nodes of the network. The data banks obtained by this procedure allow the distributed system to easily adapt to the substation topology. This is the case, for instance, of power evaluated as a function of voltages and currents available at sometimes far apart terminals of CTs and VTs. The digital processors generate the measures of currents, voltages, active and reactive powers, frequency, etc. based on the received data banks. Results of a laboratory prototype system are presented. Although allowing only on/off commands in this first version, the distributed system is able to be transformed into an hierarchical distributed control network. The paper also describes the principles by which microprocessor based protection relays in a dedicated protection network would be connected to the first distributed system, using it for security purposes and for transmitting fault recording data whenever necessary.