| 摘要 |
PURPOSE:To confine the drop time of supply voltage to the minimum by connecting a battery for backup to the primary side of a power supply circuit quickly when the voltage of a commercial power source has dropped below the fixed voltage. CONSTITUTION:When a commercial frequency AC power fails, the output of the rectifier 1a of a rectifying circuit 1 vanishes, but since a large capacity of capacitor C1 is inserted on the output side of the rectifier 1a, the output terminal voltage of the rectifying circuit 1 does not become OV immediately, and the voltage falls slowly. Thereupon, the difference of voltage applied to the two input terminals of a comparator COMP becomes below the set value. For this reason, a relay RL is restored. By the restoration of the relay RL, a contact rl opens, and the FET of a switch part 6 becomes on, and it connects the battery 2 for backup to the primary side of a power supply circuit 4. The power supply circuit 4 continues the operation and continues the power supply to a load 7. |
