| 摘要 |
<p>PURPOSE:To improve insulating capability to earth and to detect disconnection of a line surely. by constituting a DC closed circuit of a communication line, a photocoupler, a solar battery and a constant -current circuit which are connected in series. CONSTITUTION:A solar battery SS that generates electric power by luminous energy of an electric bulb LT is installed in a terminal station A, and electromotive force is converted to specified constant current (i) by a constant current circuit CC. The constant current (i) is supplied to a photocoupler PC in a terminal station B through a light emission diode DI of a photocoupler PC station A, a choke CH and a transmission line LN. Accordingly, if the transmission line LN is disconnected, the constant current (i) does not flow, so that a light receiving transistor PT of photocouplers PT in terminal in terminal stations A, B go to off state and disconnection can be detected.</p> |
