| 摘要 |
PURPOSE:To protect a main transformer against damage by providing a reclose blocking means for detecting and storing a large current at the time of blow out of fuse and blocking a main circuit breaker from being closed if an AC voltage is being applied onto a pantograph. CONSTITUTION:Upon blow out of a DC fuse 11 by an excessive current due to failure of AC/DC switching operation, a current flows through a current transformer 12 to turn the switch of a current detecting circuit 13 ON thus opening a main circuit breaker 2 subsequently. Since the switch of the current detecting circuit 13 is turned ON when an output relay 10a is turned ON, closing coil 2a of the main circuit breaker 2 can not be excited and reclosing thereof is blocked. Consequently, AC voltage is not applied onto the DC fuse 11 under fuses state, resulting in prevention of fault such a breakdown. |
