| 摘要 |
PURPOSE: To disconnect the input line of an uninterruptible power supply from a commercial AC line by detecting the direction of power flow through a current flow direction detector and actuating a backup input line isolation switch upon detecting a reverse power flow. CONSTITUTION: Current flow is detected by a power flow direction detector 151. When a reverse current flow from a battery voltage source 120 is detected, a switch control circuit 152 closes a relay switch 155 in response thereto. Consequently, a switch 104 is actuated through a relay 156 to open the contact of a mechanical switch 104 and a main AC source voltage is interrupted from an uninterruptible power supply input at the input terminals 101, 102. |
