Designing of Numerical Directional Overcurrent Relay

This paper gives an insight into designing of numerical directional over-current relay for distribution system using real time signals. For fault detection differential sampling method is used. Real time signals are converted in discrete form using an advanced analog to digital conversion device Advantech USB 4711/A. User interfacing is designed using visual basic software which generates the characteristics and performs the relay action. The relay is tested under various conditions and satisfactory results were obtained.