| 摘要 |
PURPOSE:To carry out the isolation and detection of the fault for the subscriber line and the network by forming the subscriber circuit and the current division circuit to the trunk in the telephone exchange system. CONSTITUTION:Subscriber line RS is connected with outgoing register trunk ORT. When the defective connection is decided as the result of the channel continuity test, contact co of the cut-off relay is made. And current Ib is flown in division to relay LR of the subscriber circuit. In this case, current Ib is larger than the working current of relay LR with the subscriber put under the off-hook state, and thus the fault of network NW is detected. In case, current Ia flowing to relay A is smaller than the working current of relay A with the subscriber put under the off-hook state, the fault of the subscriber line can be detected. |
