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…
Differential Relay Application: The principle of operation depends on a simple circulating current principle where the difference of the currents of the two CTs flows through the relay under normal conditions or even under faults…
Distance Relays Types and their Applications: In applying relays to a transmission system it is necessary to state the relay characteristic in the same terms that the system conditions are stated. This is especially true…
Directional Overcurrent Relays in Power Systems: Directional Overcurrent Relays in Power Systems - Relay connections must be made so that the currents and voltages applied to the relay during the various fault conditions which may…
Single Phase Directional Relay: Single Phase Directional Relay - The general Eq. (4.8) suggests that for directional control the individual torques, viz. K |A|2 and K′ |B|2 should be eliminated. Considering a voltage current directional relay the…
Directional Relays: Selective protection cannot be achieved with time graded overcurrent protection systems in ring or loop systems as well as in radial circuits with two end power supply. A directional feature is incorporated in…
Time Current Relay Application: Time Current Relay Application - Overcurrent and earth fault protective gear can be made discriminative by grading the operating times of successive devices. The pickup currents are adjusted in such a…