| 摘要 |
PURPOSE:To prevent the input and output of a transformer from becoming open even when a fuse blows by connecting one of plural taps of the transformer to a semiconductor switch which has no fuse and others to a series circuit of a fuse and a semiconductor switch. CONSTITUTION:Taps T1-T3 are provided at the input side of an automatic transformer; and a reverse parallel semiconductor switch SW circuit 10 is connected to the tap T1, the series circuit 2 of a protection fuse FS5 and a reverse parallel semiconductor SW6 is connected to the tap T2, and the series circuit 3 of a protection FS7 and a reverse parallel semiconductor SW8 is connected to the tap T3 respectively. If the SWs 6 and 8 are broken to flow a bridge current ib and either or both of the FSs 5 and 7 blow, a fusion detection signal is sent from a fusion detector 12 or 13 to an ignition control circuit 11. The circuit 11 supplies an ignition pulse to the SW10, which is turned on forcibly. In this case, a bridge current ia is suppressed by a current limiting reactor 9. Consequently, even when the circuits 2 and 3 are opened, the SW10 is connected and the input and output of the transformer 1 are closed, so that power transmission from the output side is never stopped. |
