| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent arc generation and protect circuit devices when changeover is made from supply of direct-current power to halt of the supply. <P>SOLUTION: In a wiring device 1 inserted in power supply lines Lp1-Lp4, if a changeover switch 3 switches from an ON-state to an OFF-state, then a first switch 41 of a control section 4 switches from a closed state to an opened state, and a second switch 42 switches from an opened state to a closed state. Subsequently, a capacitor 44 is discharged gradually and a voltage Vc between ends of the capacitor 44 is reduced gradually. A control IC 45 reduces a pulse density of a control signal Sig gradually as the voltage between the ends of the capacitor 44, namely an input voltage comes down gradually. In a power MOSFET2, its voltage between a drain and a source is increased gradually as the pulse density of the control signal Sig is reduced gradually, thereby gradually releasing an electromagnetic energy stored in the power supply lines Lp1-Lp4. <P>COPYRIGHT: (C)2011,JPO&INPIT |
