| 摘要 |
PURPOSE:To prevent generation of an overcurrent, so that a variation of a power supply voltage is not generated, by delaying the power sent out of a selected power supplying circuit, by a prescribed time from a switching time point. CONSTITUTION:An AC power control device for supplying a current to a heater which has been embedded in a window-pane provided on a cockpit of an aircraft is provided with a delaying circuit for delaying an electric conduction start time point of the first one cycle at the time of switching, by a prescribed time. For instance, a flip-flop 57, resistances 50d, 50e, a capacitor 51d, diodes 55a, 55b, an AND circuit 58 are provided, so that the follow-up is delayed a little by the first one period of an AC waveform, at the switching time point of a current value. That is to say, when the flip-flop 57 is its output is delayed by the time determined by the resistance 50d and the capacitor 51d, and outputted, and the AND circuit 58 is delayed by its delay time portion and become active. Also, by providing a timer 52c, the continuation time of a waveform before switching in a waveform switching time point is lengthened a little. In this way, an overcurrent caused by mismatching of a phase can be prevented.
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