| 摘要 |
PURPOSE:To eliminate connection of AC 200 V to an AC 100 V input power source even if AC 200 V is erroneously connected to an AC 100 V input unit by forming a structure for detecting whether an input voltage is AC 100 V or AC 200 V to open or close an input relay. CONSTITUTION:When AC 200 V is connected between AC input terminals 1 and 2, the output voltage V3 or a 3-terminal regulator Z1 becomes always lower than a rectified output voltage V5. Since a rectified and stepdown voltage V5 is a voltage VBE1 or lower at times t12-t24, a transistor Q1 is turned OFF. Since voltages V3<V4 is satisfied at times t22-t32, the internal output transistor of a comparator Z2 is turned ON. Thus, the voltage V5 is clamped at the voltage VCE of an internal transistor of the comparator Z2, and the transistor Q1 remains OFF. If the transistor Q1 is not turned ON, a voltage is not applied to a coil RL1, and a contact rl1 is not closed. |
