15-11-2014, 10:41 AM
Abstracts: The project is designed to develop an automatic tripping mechanism for the three phase supply system. The project output resets automatically after a brief interruption in the event of temporary fault while it remains in tripped condition in case of permanent fault. A set of switches are used to create the LL, LG and 3L fault in low voltage side, for activating the tripping mechanism. Using the 555 timer circuits, the duration of fault is determined and decision is made regarding whether the fault is of short duration or long duration using LM358. Short duration fault returns the supply to the load immediately called as temporary trip while long duration shall result in permanent trip.