| 摘要 |
PURPOSE: To realize quick response to phase disturbance by monitoring the difference of output voltage between both AC power supplies, releasing parallel connection when the difference exceeds a predetermined value and prohibiting reconnection for a predetermined time. CONSTITUTION: When two independent AC power supplies 10, 18 are connected in parallel by turning on a contactor 28, difference of output voltages V1 , V2 between both AC power supplies 10, 18 is monitored by means of a monitor circuit 34. A capacitor C2 is connected with the output of the monitor circuit 34 incorporating means Q1 for short-circuiting the capacitor C2. When the terminal voltage of the capacitor C2 exceeds a predetermined level at a point 42, a drive circuit 46 for the contactor 28 is operated. When the difference of voltages V1 , V2 exceeds a predetermined level, the means Q1 is turned on to discharge the capacitor C2 and the contactor 28 is turned off. At the time of reconnection, turning-on of the contactor 28 is delayed by the charging time of the capacitor C2. |
