| 摘要 |
By forming current jump or surge signals and voltage jump or surge signals, in accordance with the changes as a function of time of the line current and line voltage in relation to the steady-state course of the current and voltage and comparison of such jump or surge signals with a threshold value, dependent upon the other jump or surge signal, or an appropriate threshold value function, there can be derived trip boundaries in the surge signal plane. Exceeding such trip boundaries in a direction from the inside towards the outside can be utilized as a fault criterion for producing a trip signal. With suitable trip boundaries, at least inclined in sections towards the coordinate axes owing to the aforementioned dependency of the comparison threshold values, which trip boundaries also may be curved, and arranged in spaced relationship from the coordinate-null point in the four quadrants of the surge signal-coordinate system there is realized a rapid fault detection which is comparatively foolproof against faulty tripping and by determining the quadrants where there occurs the initial exceeding of the threshold value, there likewise can be realized an equally rapid and positive fault-direction detection.
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