| 摘要 |
<p>The invention relates to a method for determining a line section (10) afflicted with an earth fault in a three-phase energy supply network having an isolated or resonant-earthed star point, wherein a zero-phase-sequence system voltage and a zero-phase-sequence system current are detected at both ends of the line section (10) by means of electrical protective devices (13a, 13b) and direction information is obtained therefrom, the direction information specifying whether an earth fault lies in the forward direction or in the backward direction relative to the respective measuring point (12a, 12b). In order to specify a relatively simple method for determining a line section afflicted with an earth fault, wherein the line afflicted with an earth fault can be determined without having to switch off parts of the electrical supply network, a method is proposed, wherein a complex zero-phase-sequence system apparent power is determined from the zero-phase-sequence system voltage and the zero-phase-sequence system current by means of the protective devices (13a, 13b), the direction information is derived from the sign of a component of the zero-phase-sequence system apparent power, the pieces of direction information of both ends are compared to each other, an earth fault on the line section (10) is recognized if both pieces of direction information indicate a forward direction, and an earth fault outside the line section (10) is recognized if at least one piece of direction information indicates a backward direction. The invention further relates to a corresponding electrical protective device (13a, 13b).</p> |
