| 摘要 |
PROBLEM TO BE SOLVED: To provide a protection circuit capable of stably protecting an electric circuit from lightning surge current. SOLUTION: A DC-voltage generating circuit 9 is such that normal mode choke coils 17 and 18 and a common-mode choke coil 19 for allowing a commercial AC current to pass therethrough, while cutting off a lightning surge current are provided between wires L1 and L2 and a transformer 22. A lightning surge current flowing into the wires L1 and L2 are cut off by the normal mode choke coils 17 and 18 and the common-mode choke coil 19, and then the voltage of the wires L1 and L2 is increased, causing discharging in discharge gaps 13 to 15. Consequently, even when the input impedance of the transformer 22 low, the transformer 22, etc. can be stably protected from the lightning surge current. COPYRIGHT: (C)2011,JPO&INPIT
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