| 摘要 |
PURPOSE:To make it possible to independently set a synchronism detection tolerant width to a commercial power source source and a power-failure free power source apparatus, by triggering a pair of monostable multivibrators by two AC voltages for investigating synchronous relation and taking AND of output thereof. CONSTITUTION:When the outputs of comparators 8a, 8b, to which voltages of an inverter 1 and a commercial power source 2 are inputted, change from high to low, monostable multivibrators 9a, 9b are triggered and pulses with pulse widths Tfa, Tfb are generated. Therefore, if the phase of voltage in the side of the inverter 1 is taken as a basis, the output of an AND circuit 10 holds a high level, even if the phase in the side of the commercial power source 2 is delayed in the range of the pulse width Tfa, to trigger the monostable multivibrator 11 and synchronism is displayed. Contrarily, if the phase of the voltage of the commercial power source is taken as a basis, synchronism is similarly displayed even if the phase of the voltage of the inverter 1 is delayed within the time of the pulse width Tfb. By this method, pulse widths are respectively altered in an advance side and a delay side to enable the alteration of a synchronism detection tolerant width.
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