| 摘要 |
PURPOSE:To prolong the life of a relay contact, by burdening the switching of a large current to a switching diode. CONSTITUTION:In a remote control relay driving a remote relay with a local operating switch, when a selector switch is selected to the terminal 3, a voltage drop by a display lamp 19 is eliminated and the full voltage of an AC power supply 7 is applied across a resistor 15, then the base current of a transistor TR T1 rapidly increases and a drive current flows to a relay coil 9, and a diode switching circuit 14 is switched to a diode 13. Thus, the base current of the TR T1 is zero and the drive current of the relay coil 9 is also zero. In this case, a display lamp 18 illuminates and 19 distinguishes. Thus, the inversion of an output contact 17 of the relay 9 can be known at an operating switch 20 located at a remote point via a transmission line 8, and the current flowing to the relay contact can be reduced. |
