Distribution power line communication system including a messenger wire communications link

• US 4,012,733 A
• Filed: 10/16/1975
• Issued: 03/15/1977
• Est. Priority Date: 10/16/1975
• Status: Expired due to Term

• Current Assignee: ABB Power T&D Limited (ABB Limited)
• Original Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Inventors: Whyte, Ian A.
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Groody, James J.
• Application Number:
  US05/622,915
• Time in Patent Office: 516 Days
• Field of Search: 340/310 R, 340/310 A, 340/310 CP, 179/2.5 R
• US Class Current: 375/258
• CPC Class Codes: H04B 2203/5487 cables
• CPC Class Codes: H04B 3/54 Systems for transmission via power distribution lines

Abstract

A distribution power line communication system wherein communication signals are transferred between a communication terminal at a substation and communication terminals at customer locations. The communication signals are transferred between the terminals by using a two-conductor line, with one of the conductors effectively grounded and with the other of the conductors effectively isolated from ground. The conductor which is isolated from ground provides a conduction path which travels along the primary distribution line to a distribution transformer location. At this location, the conduction path is transferred to a messenger wire which supports other transmission lines between various distribution transformer locations. The messenger wire is suitably isolated from ground and the conduction path is transferred to separate secondary distribution lines adjacent to the messenger wire. The final portion of the ground-isolated conduction path which directs signals to the communication terminals at the customer locations is provided by the secondary distribution lines and by the service lines extending to the customer locations.

Claims

1. A distribution power line carrier communication system transmitting carrier signals to electrical customer load locations served by a distribution power line system carried on support poles, said communication system comprising:

a primary line conductor of said distribution system transmitting said carried signals and carried by said support poles;

a plurality of secondary line conductors of said distribution system carried by predetermined ones of said support poles for connection to said customer load locations;

at least one distribution transformer connected between the primary and secondary distribution line conductors;

a cable supporting messenger wire having a high resistance and being suspended between said predetermined ones of said support poles;

frequency responsive impedance means connected between said messenger wire and ground potential, said impedance means having a high impedance at the carrier signal frequencies and a low impedance at the power line frequency;

first signal coupling circuit means connected between said primary line conductor and said messenger wire for transmitting carrier signals therebetween and around said one distribution transformer; and

second signal coupling circuit means connected between said messenger wire and said plurality of secondary line conductors for transmission of said carrier signals between said messenger wire and said customer load locations.