Electricity: electrical systems and devices – Safety and protection of systems and devices – With specific quantity comparison means
Patent
1982-10-22
1984-05-22
Salce, Patrick R.
Electricity: electrical systems and devices
Safety and protection of systems and devices
With specific quantity comparison means
361 80, 361 84, H02H 340
Patent
active
044504977
ABSTRACT:
Protective relay apparatus for detecting the direction or distance to a fault from the measuring point on an ac electrical power transmission line using current and voltage deviation signals. The deviation signals represent the changes induced by the fault from the steady-state pre-fault magnitudes. Trajectories are plotted on an X-Y plane using the voltage deviation signal as the X-axis coordinate and the differentiated current deviation signal multiplied by the line reactance to the balance point as the Y-axis coordinate. Due to the use of the differentiated current deviation signal, the trajectories are straight lines. The threshold boundaries for determining the distance to or direction of the fault are time-varying lines of unit slope representing the pre-fault voltage at the fault point. For a fault outside the balance point, the trajectory lags the threshold boundary; for a fault at the balance point, the trajectory is always equal to the balance point voltage; and for a fault inside the balance point, the trajectory always leads the threshold boundary.
REFERENCES:
patent: 3599044 (1971-08-01), Takemura
patent: 3700919 (1972-10-01), Stich
patent: 4287547 (1981-09-01), Vitins
patent: 4371907 (1983-02-01), Bignell
DeAngelis, Jr. J. L.
Salce Patrick R.
Westinghouse Canada
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