| 摘要 |
A method and an apparatus for differential protection of a three phase electric connection of an electric system, the apparatus comprising: means (10A, 10B) for determining a value of an operate quantity, which operate quantity is based on a difference between current quantities at a first point and a second point of the electric connection (20), and means (10A, 10B) for detecting a fault in the electric connection (20) between the first point and the second point if the value of the operate quantity exceeds a value of a predetermined threshold quantity, wherein the operate quantity is based on a difference of residual currents at the first point and the second point, or a quantity indicative thereof, and a coefficient indicative of an angle between a residual voltage of the electric connection (20) and the difference of residual currents at the first point and the second point. |
