| 摘要 |
<p>A device for preventing an inrush current which may damage parts of an electric apparatus. The device prevents the inrush current when the apparatus returns from an instantaneous power failure condition to the normal condition. The voltage across a capacitor (16) is amplified by an amplifier (22) and then converted into a digital output by an A/D converter (24). Based on the digital output, a processor (26) of the device judges the state of the electric apparatus. In case of interruption of an AC power source (10), the voltage across the capacitor (16) decreases. When the processor (16) judges that the voltage becomes below a preset one, the processor (26) closes relay contacts (rl2) that serve as auxiliary switches through a latch circuit (28) and a transistor (T2) to temporarily connect the AC power source (10) to a rectifier circuit (12) via the relay contacts (rl2) and current-limiting registors (R). After the voltage across the capacitor (16) increases, namely, after the AC power source recovers, the processor (26) again connects the AC power source (10) to the rectifier circuit (12) via relay contacts (RL1) of an electromagnetic contactor (MCC) that works as a main switch.</p> |
