| 摘要 |
1318055 Repeater power supply equipment STANDARD TELEPHONES & CABLES Ltd 5 Aug 1970 37733/70 Heading H4R In a transmission system a phantom circuit formed by two pairs of conductors is used to feed power at normal mains frequency to repeaters distributed along the transmission path and a D.C. power supply equipment is connected across the phantom circuit to supply one or more repeaters. The input impedance of the power supply equipment is designed to produce a reactive voltage drop that is at least ten times the voltage drop along the line. Thus the value of the supply voltage is made virtually independent of the length of the line and the number of repeaters supplied. Mains power is introduced by transformer (6) into the conductor pairs (3), Fig. 1 (not shown). At the repeater station for a carrier transmission system the power supply equipment 15 has its input connected between shunting capacitors 24 forming part of a physical filter inserted in one side circuit of the system to by-pass the carrier repeater 12. A split inductor 28 is used to partially compensate the reactance of the capacitors and thus reduce the reactive voltage required to a safe level whilst being high enough to make the system supply voltage practically load independent. The power supply equipment 15 includes a bridge reactifier feeding a series resistor and shunt Zener diode forming a voltage control circuit. The supply can be taken through a transformer to give added lightning protection and this transformer preferably is adjustable. In an alternative embodiment a centre tapped choke could be used to provide the connections between the power supply equipment and the phantum circuit, Fig. 1 (not shown). It is also stated that the supply voltage transformer (6) could be eliminated if the supply were taken to tapped impedances connected across each pair. |
