| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a compact bus protection relay at low cost for requiring only one input circuits for each isolator by fetching, for example, only the signal from a contact point (a) as an isolator palette condition. <P>SOLUTION: The bus protection relay comprises a collective bus protection calculation circuit 51, a first bus protection calculation circuit 52, a second bus protection calculation circuit 53, and an LS monitor control circuit 7 which outputs switch signals SL#1bus and SL#2bus based on the isolator palette condition and abnormal LS connection detection signals Idc>, Id1>, Id2> from the protection calculation circuit 51-53, and also outputs the switch signals SL#1bus and SL#2bus by correcting the palette condition if an abnormal palette condition change is detected based on the abnormal LS connection detection signals Idc>, Id1>, Id2> at close change of isolator palette condition. It also comprises a line switching circuit 4 which performs switching operation for selecting whether or not to output line currents I1-IN to the first and second bus protection calculation circuits 52 and 53 based on the switch signals SL#1bus and SL#2bus. <P>COPYRIGHT: (C)2009,JPO&INPIT |
