| 摘要 |
<p>PURPOSE:To minaturize facilities without increasing a failure rate by stringing a standby line on a feeder line between a master station and line concentrator. CONSTITUTION:Lines PL11, PL12, PL1N+n are lines for supplying sufficient power to the line concentrator, and PL21, PL22 PL2N+n are standby lines. IF the breaking of a line with line resistance R1j or R2j occurs, the combined resistance of feeder line PL changes. This change is compared by comparator circuit COM1 and displayed on display circuit DIS1 of master station OF1 by way of transmitter circuit SED1 and supervisory line CL1. Comparator COM2 also operates in the same way. Therefore, DIS1 is operated while standby lines become indispensable with the (n+1)-number couples of lines broken, and when (m)-nunber lines are broken, it is possible to indicate the need for repairing through the operation of display circuit DIS2.</p> |
