Distance Protection by Reactance Relays

Distance Protection by Reactance Relays: Like impedance relays, Distance Protection by Reactance Relays are also amplitude comparators and thus require an additional directional unit. Although the performance of reactance relays on single-fed systems is not unduly affected by fault resistance, there may be occasions in double-fed systems where errors in reach may occur, particularly when […]

Scheme of Distance Protection

Scheme of Distance Protection: In developing an overall Scheme of Distance Protection, it is necessary to provide a number of relays to obtain the required discrimination. Modern practice is to adopt definite distance method of protection applied in 3 zones (steps). A number of distance relays are used in association with timing relays so that […]

Reach of Distance Relay

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 corresponding distance is known as the Reach of Distance Relay. To convert primary impedance (impedance of the line referred to […]

Fault Resistance Calculation

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 the resistance of earth would mean the resistance of fault path through the tower, tower footing resistance and earth return. […]