| 摘要 |
PURPOSE:To protect a power supply apparatus against breakdown due to erroneous connection of external input DC power supply by switching the polarity thereof such that power is fed constantly with fixed polarity to a load circuit. CONSTITUTION:A duplex bimetal switching circuit 3 for switching the input DC power supply terminals 2a, 2b simultaneously on the positive and negative polarity sides thereof has a switching output terminal A connected with a circuit 4 for determining the polarity of power supply. The circuit 4 determines the polarity of an input DC power supply and when the DC power supply is connected normally, it is fed as it is to a load circuit 6. When the DC power supply is connected reversely, an overcurrent is fed to the bimetal switching circuit 3 which thereby functions to switch the polarity of the DC power supply thus feeding power with fixed polarity to the load circuit 6. This constitution protects a power supply apparatus or set against breakdown due erroneous connection of external input DC power supply. |
