| 摘要 |
PROBLEM TO BE SOLVED: To prevent a line from being switched unnecessarily owing to rainfall. SOLUTION: The rainfall warning detecting device 10 provides a previously set protection time by an other-station rainfall warning control circuit 2 when a rainfall warning transferred from the other station is reset to extend a reset time correspondingly and holds rainfall warning transferred from the other station last by the other-station rainfall warning circuit 2 when all-disconnection detecting circuit 3 detects all lines being out of frame synchronism owing to rainfall to make the rainfall warning of the other station effective even in case of the line disconnection. Further, when some line recovers, an other-station rainfall warning selecting circuit 1 inputs the rainfall warning of the other station by using the line having recovered to accurately input the rainfall warning from the other station at the time of the line recovery.
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