| 摘要 |
PURPOSE:To realize a reliable protection of a bridged double bus and to obtain a highly reliable bus protective relay by providing a first mans for detecting fault in the combination of double bus, second and third sans for detecting fault in the individual bus and a fourth means for operating the second and third sans as the first sans upon detection of bridging. CONSTITUTION:Electrical amounts I' proportional to the currents I flowing on a transmission line L connected with buses are selected sequentially by means of a multiplexer 3 and then converted through an A/D converter 4 into digital amounts (i). A protective operation unit 5 employs the digital amounts (i) in the operation of combined protection and provides an output to an output circuit 6 upon decision of an internal fault in a bus. The protective operating unit 5 further performs operation of individual protection based on the digital amounts (i), conditions of a disconnector(LS) fed from a control signal input circuit 7 and a current in a line connected with the bus and provides an output to the output circuit 6 upon decision of an internal fault in that bus. The output circuit 6 a selective interruption output for the bus based on the combined and individual protection outputs and LS conditions. |
