| 摘要 |
PURPOSE:To easily discover an erroneous connection by employing a specific voltage as a reference, and calculating and displaying the phase difference of a current thereto in a digital bus protective apparatus. CONSTITUTION:A current from a power source 1 to a bus 2 to be protected and a current from the bus 2 to a plurality of feeders 3 are obtained by a current transformer 4 and an auxiliary current transformer 5, and input to the sample-holding circuit 9 of a digital bus protective relay 8. The voltage of the bus 2 is obtained by a transformer 15 and an auxiliary transformer 16, and sample-held by a sample-holding circuit 9. The sample-held current, voltage are sequentially multiplexed by a multiplexer 10, A/D-converted by an A/D converter 11, and input to a CPU 12. A differential current calculated by the CPU 12 is displayed on a display 14 with the phase designated by a setter 13 as a reference, and its phase relationship is displayed on a display 17. Thus, erroneous connections of many current transformers can be easily discovered to improve its maintenance and reliability. |
