SA100 (Bay Control Unit) and SA200 (Bay Monitoring Unit) are the electronic units, Bay Unit, belonging to the STCE family for substation automation. They are installed at the electrical stalls, are interconnected via optical LAN controlled by a station computer, and represent the ideal system for operators of high and very high voltage electricity networks, who need to renew the control and automation systems of the stations in order to maximize the efficiency and quality of the service offered.