Reach of Distance Relay: A distance relay is set to operate up to a particular value of impedance; for an impedance greater than this set value the relay should not operate. This impedance, or the…
Fault Resistance Calculation: Fault Resistance Calculation consists of two components, the resistance of the are and the resistance of earth. The second component is present only when it involves an earth-fault. In such a case…
Time Grading of Distance Relay: Two methods of Time Grading of Distance Relay are shown in Fig. (5.18). First Method is the distance time method at (a) has the operating time increasing steadily with increasing…
Principle of Distance Relaying: The Principle of Distance Relaying is governed by the ratio of voltage to current at the relay location and the operating time of the relay automatically increases with an increase of…
Directional Earth Fault Relay: In the case of Directional Earth Fault Relay the angular relationship of residual current and residual voltage is independent of the faulted phase and is governed only by the R/X ratio…
Overcurrent Earth Fault Protection: Overcurrent Earth Fault Protection - Earth-fault protection can be provided with normal overcurrent relays, if the minimum earth-fault current is sufficient in magnitude. The magnitude of earth-fault current is usually low…
Overcurrent Protection of Feeders: Overcurrent relays offer the cheapest and the simplest protection for lines. The maximum load currents must be known to determine whether the ratio of the minimum fault current to maximum load…
Types of Feeder Protection Relay: A composite transmission system may use one or more of the following types of Feeder Protection Relay. Overcurrent Protection: This is of two types: (i) nondirectional time and current graded…