| 摘要 |
PROBLEM TO BE SOLVED: To provide a small-sized DC breaker capable of cutting off relatively large DC electricity using a conventional small-sized switch and being excellent in durability. SOLUTION: A first switch 3 and a second switch 4 are connected in series to a DC power source 1 and a load 2, a capacitor 5 and a resistor 6 are connected in parallel to the first switch 3, a varistor 7 is connected in parallel to the first switch 3 and the second switch 4, and a switch driving circuit 8 for switching the first switch 3 and the second switch 4 in turn with a time lag is provided. When the first switch 3 is opened, the capacitor 5 absorbs the arc energy of the first switch 3, the current flows to the capacitor 5, the resistor 6 and the varistor 7, and the current is limited by the resistor 6 and the varistor 7. The varistor 7 protects the capacitor 5 from overvoltage. When the second switch 4 is opened after a lapse of a predetermined time, a small current which has been limited is cut off by the second switch 4. COPYRIGHT: (C)2009,JPO&INPIT
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