| 摘要 |
PURPOSE:To detect a fault where a hopping switch is interrupted or conducted by detecting respectively an input/output of the switch, using a control signal of the switch so as to compare both the detected waveforms and detecting the operation. CONSTITUTION:When the hopping signal 6 does not transmit a signal from a branch circuit 51, a detection circuit 21 genertes no signal. An AND circuit 11i inputs an output of a detection circuit 10i and a selection control signal from a terminal station device 8 and transmits a signal, an EOR circuit 13 transmits a ''1'' signal and an alarm is raised from a hold circuit 14. If a fault conducting the switch 6 takes place, since the switch 6 output a summing signal between the signal from a branch circuit 5i and a signal selecting a signal from each branch circuit, a signal is outputted from the detecting circuit 12. A signal from each branch circuit and each control signal from a terminal station device are fed to AND circuits 111-11N, and its output signal is in phase with an output signal of the switch 6 at normal state. Thus, the holding circuit 14 is operated by an output signal of an EOR circuit 13. |
