| 摘要 |
PURPOSE:To detect whether a current is supplied to an AC electric circuit, by forming a converting apparatus for converting single-phase or multiphase AC input to DC into bridge constitution and turning transistors ON/OFF, which are provided in the number corresponding to the number of the phases of the rectifying element connected to a DC output terminal, on the basis of the presence of the AC inputs of the corresponding phases. CONSTITUTION:In a converting apparatus 11 for converting three-phase AC inputs to DC, arms 11U-11W are provided between the positive side DC terminal P and negative side DC terminal N. The diodes DU-DW connected to the terminal P and the transistors QU-QW connected to the terminal N are provided to the arms 11U-11W. Condensers CU-CW are respectively inserted between the emitters and collectors of the transistors QU-QW and the respective collectors are connected to a drive power source E+ through resistors rU-rW and respective bases are connected to the AC input points (a)-(c) of the arms 11U-11W. The collector outputs eU-eW of the transistors QU-QW are respectively guided to judge devices 12U-12W to be compared with judging voltage EO. When each of the inputs eU-eW becomes larger than the voltage EO, the judge devices 12U-12W sent out an open phase detection signal X through an OR element 13.
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