Introduction to Protective Relays

Essential Qualities of Protection Systems

Essential Qualities of Protection Systems: Every Protection Systems which isolates a faulty element is required to satisfy four basic requirements: reliability; selectivity; fastness of operation; and discrimination. Without reliability and selectivity the protection would be rendered largely ineffective and could even become a liability. Reliability: Reliability is a qualitative term. Quantitatively it can be expressed …

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Zone Protection

Zone Protection: The Zone Protection is that part of a power system guarded by a certain protection and usually contains one or at the most two elements of the power system. The zones are arranged to overlap so that no part of the system remains unprotected. Figure (1.1) shows a typical arrangement of overlapping Zone …

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Fault Meaning

Fault Meaning and Statistics: Fault Meaning and Statistics – It is useful to have some idea of the frequency of the incidence of faults on the different items of equipment in a power system. This information is of help in considering the problems of design and application of protection. Table 1.1 gives an idea of how faults …

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