| 摘要 |
PURPOSE:To immediately detect a trouble in a power line with a very high sensitivity, by detecting the trouble from the variation rate of maximum of a single- phase AC quantity. CONSTITUTION:The single-phase AC quantity e is entered into a transformation circuit 2 and changed to an appropriate level. The changed quantity is applied to a square circuit 7, thereby producing an output e1. The output e1 is applied to a shift addition circuit 13 through a shift circuit group 11 consisting of shift circuits 8-10 and through an addition circuit 12, thereby producing outputs e1-e3 and eADD. These outputs are entered into a detection circuit 17 consisting of a differentiation circuit 14, a full-wave rectifier circuit 15 and a level detection circuit 16. The differentiation circuit 14 generates an output eD. The full-wave rectifier circuit 15 generates an output eC from the output eD. The level detection circuit 16 compares the output eC with a predetermined level L. When the output eC is higher than the level L, the level detection circuit 16 produces an output eK. Thereby, it is detected that a trouble has occurred in the power line. |
