| 摘要 |
PURPOSE:To stabilize power supply, by transiting a voltage control oscillator to self-run state upon occurrence of power interruption and switching the voltage control oscillator to synchronous oscillation when the power is recovered and the difference in phase between a commercial source voltage and the output voltage from an uninterruptible power source equipment decreases sufficiently. CONSTITUTION:Upon occurrence of power interruption, a latch circuit 14 is reset based on an output signal fed from a power interruption detector 7 to switch first and second switching circuits 4, 5 to the side of terminals (b). Consequently, a voltage control oscillator 3 transits to its self-run state. At a time point when the commercial power source is recovered and the difference in phase between the commercial source voltage and the output voltage from an uninterruptible power source equipment decreases to a sufficiently low level, the latch circuit 14 is set based on an output from a phase comparator 11 to switch the first and second switching circuits 4, 5 to the sides of terminals (a). Consequently, the voltage control oscillator is switched to synchronous oscillation with the output from the phase comparator 11. |
