| 摘要 |
PURPOSE:To isolate faulty section reliably, by connecting a series circuit of a capacitor and a semiconductor switch in parallel with a protective device for separating the faulty section, upon occurrence of fault in a power converter having main circuit constituted with semiconductor elements, and discharging the capacitor. CONSTITUTION:Output from a DC power source 10 is fed through a protective fuse 7 to a power converter A, which produces AC power for driving a load 9. A series circuit of a thyristor 13 and a capacitor 12 is connected in parallel with a protective fuse 7, where the capacitor 7 is charged previously through a resistor 14. When an excessive current Is flows through the power converter A due to fault of the load 9, a CT16 detects the excessive current and the thyristor 13 is energized then the capacitor 12 is discharged thus lapping current Ic over the current Is. Consequently, the fuse 7 is blown off reliably even by such fault current Is as having magnitude insufficient to blow off the fuse 7, resulting in reliable protection of the converter A. |
