Over current relaying and fuse protection uses the principle that when the current exceeds a predetermined value, it indicates presence of a fault (short circuit). This protection scheme finds usage in radial distribution systems with a single source. It is quite simple. Protective Relays - Technical Seminar Nov 2016 - Copyright: IEEE 2 Abstract: Protective relays and devices have been developed over 100 years ago to provide “lastline”of defense for the electrical systems. They are intended to quickly identify a fault and isolate it so the balance of the system. Selective short-circuit protection can be achieved in different ways, such as: Time-graded protection Time- and current-graded protection A straightforward way of obtaining selective protection is to use time grading. In one circuit, we've used an NTC to prevent inrush current., the trip signals of the relays are fed back to the CBs. The configuration and parameters of the models may be changed. The aim of this technical article is to cover the most important principles of four fundamental relay protections: overcurrent, directional overcurrent, distance and differential for transmission lines, power transformers and busbars. Contents: For simplicity in explaining the key ideas, we.
