| 摘要 |
PURPOSE:To prevent the overload of a power circuit by controlling the output voltage of the power circuit through operating a change-over switch by the output values of two detecting elements for detecting the output voltage of the power circuit and the input voltage of a load. CONSTITUTION:At the time of starting an apparatus, the common terminal C of change-over switches SW3, 4 are connected with a terminal A and the output voltage of a power circuit 1 is detected by a first voltage detector 5. The output voltage of the power circuit 1 is compared with a reference voltage 6, error-amplified 7, and stabilized via control circuit 8. Then, the input voltage of a load 2 is detected by a second voltage detector 9 and compared with a reference voltage 10. When there is an error exceeding a predetermined value, coils 3a, 4a are energized so that SW3, 4 are turned to a terminal B and the output voltage of the power circuit 1 is controlled like when an apparatus is started. Also, when the input voltage of the load drops by any abnormality neither the coils 3a, 4a operate nor the voltage of the power circuit 1 rises. Thus, the power circuit 1 is prevented from overvoltage or oscillation. |
