| 摘要 |
<p>Information is transmitted on one of the phase conductors of an a.c. line in a form of a series of short-duration pulselike amplitude reductions in the voltage during one and the same half cycle, whereat the pulses form a binary code word representing the information. These reductions are generated by means of a current transformator (14) in series in the phase-conductor (4). The secondary winding is short circuited by a transistor (15) controlled by a control unit (6) to be opened for a short duration for each desired pulse. When the transistor (15) is opened, a voltage regulator (17) connected across the secondary winding restricts the change in magnetic flux in the transformator core to a maximum value dependent upon the lenght of the impulse series. The current is held over a given miniumum value during a transmission by a current regulator (27) and by connecting a load (28) to the phase conductor (4).</p> |
