ABSTRACT
Protection of present-day power systems is accomplished by a complex system of extremely sensitive relays that function only during a fault in the power system. Because relays are extremely fast, automatic oscillographs installed at appropriate locations can be used to determine the performance of protective relays during abnormal system conditions. Information from oscillographs can be used to detect the:
1. Presence of a fault 2. Severity and duration of a fault 3. Nature of a fault (A phase to ground, A-B phases to ground, etc.) 4. Location of line faults 5. Adequacy of relay performance 6. EŸective performance of circuit breakers in circuit interruption 7. Occurrence of repetitive faults 8. Persistency of faults 9. Dead time required to dissipate ionized gases 10. Malfunctioning of equipment 11. Cause and possible resolution of a problem
Another important aspect of analyzing oscillograms is that of collecting data for statistical analysis. is would require a review of all oscillograms for every fault. e beneœts would be to detect incipient problems and correct them before they become serious problems causing multiple interruptions or equipment damage.
