| 摘要 |
PURPOSE:To enable deficit voltage in the 50Hz and 60Hz districts to be detected by addition of simple circuits by arranging so that a device adapted to detect the voltage level by comparison with a reference voltage of a DC voltage obtained by rectifying the AC voltage is annexed by a phase difference detector for producing an AC voltage having a phase delay of 90 deg. from the AC voltage and its rectification circuit. CONSTITUTION:The capacitances of capacitors 11, 14 are set so as to be equal in impedance to resistors 12, 13 at 55Hz. The potential ex at a junction presents a voltage waveform delayed 90 deg. with respect to the terminal voltage eb relative to a mid point zero V. The resistance 13 and the capacitor 14 operate to delay the junction point potential ey by 90 deg. with respect to the terminal voltage ea, with the phase of the potential ey being of a waveform of opposite polarity, or 180 deg. out of phase with the potential ex. The voltages at these two points are rectified by a rectifier 15 and added to a voltage obtained after rectification by a rectifier 2 of the secondary voltage of the alternating current supplied to a control transformer 1. Thus the two phase full-wave rectified waveform is obtained and the potential ed smoothed by a resistance 3 and a capacitor 4 is free of ripples so that deficit voltage of 50Hz and 60Hz is detected accurately.
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