Electronic circuit for automatic transfer of a distribution node

This paper shows the design of an electronic prototype, which senses the values for alternating voltage in two different electric distribution systems. The device connects the load to its normal source if the voltage levels are within a permissible range, in order cases the load is connected to an alternate source. The inverse action is accomplished automatically when the voltage returns to its normal value. The main components of the device are: operational amplifiers, timers, logical gates and triacs which gives a low cost alternative. The prototype also has a manual operation stage which permits one to maneuver in permanent fault conditions or when it is necessary to undertake maintenance work