Phase Comparison Carrier Protection: The phase comparison pilot-relaying operates on the principle of comparing the phase position of the currents at the two ends of the protected section. The Phase Comparison Carrier Protection of these currents is made over carrier channels. During normal conditions or through faults the currents entering the line at one end, …
Carrier Pilot Protection and Microwave Pilot Protection: The problem of providing economically an auxiliary channel by means of pilots for long lines directed attention to carrier techniques. In this case the power line itself is used as the channel for carrying information between the two ends of the transmission line. Two different types of communication …
Pilot Wire Protection Relay: In this case the auxiliary Pilot Wire Protection Relay are provided to carry the information signals from one end to the other. Protective systems requiring the use of pilot wires on transmission lines operate on the principle of differential protection. There are basically two forms of differential protection schemes used for …
Application of 3 Phase System: In a Application of 3 Phase System, a wide variety of faults can occur, i.e. phase to phase, phase to earth, 2 phase to earth and 3 phase fault, various combinations in a Application of 3 Phase System lead to 10 varieties. Theoretically, 4 fault detectors and 18 measuring units …
Selection of Distance Relay: The factors to be considered for the Selection of Distance Relay scheme can be enumerated as follows: Speed of operation. Measuring relay characteristics. Fault coverage. Economic considerations. 1. Speed of Operation: Operating time is of great importance on systems which are liable to become unstable if the fault persists for more …
Current and Voltage Connection in Distance Relay: It is essential for the distance relay to measure the same distance between the fault and the relay under any type of fault condition. It is possible to supply the relays so that they will always measure Z1 the positive sequence impedance of the protected feeder, by suitable …
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Power Swings in Power System Protection: The impedance measured or seen by a distance relay during normal load is shown in Fig. (5.29). Normally this would be outside the tripping zone of the distance relay, but, on a very long line where the length of the line in miles exceeds the system KV, the impedance …
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 …
Distance Protection Impedance Relay: Distance Protection Impedance Relay – It has already been pointed out that the impedance is directly proportional to the length of the line, and hence an impedance relay which measures impedance can be used to recognise a fault condition and operate. As such an impedance relay has no directional feature and …
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 …