Reza Hemmati

This paper addresses both the experimental and simulation studies on application of overcurrent protective relay. The industrial overcurrent relays often have three individual settings. In this paper, the relay operating characteristics are set on normal inverse (NI) and very inverse (VI) curves. These curves operate as backup of each other. The third setting is also set on the instantaneous definite minimum time (DMT). The designated protection scheme protects the system with the least operating time.