Appl i cati on of Frequency Trend (df/dt) Rel ays and Discrete Under Frequency Rel ays for a typical Indian Utility and Industrial Installation is described. Today Indian industries are making use of Captive Power Plants (CPPe) of fairly large capacities to meet their load demands. The coordinated approach of using Frequency Trend Relays (FTR) and Discrete Under Frequency Relays (DUFR) is found useful in islanding and load shedding during slowly varying and sudden frequency dip conditions due to grid disturbances.

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