Signal repeater for a distribution network communication system

• US 4,210,901 A
• Filed: 11/13/1978
• Issued: 07/01/1980
• Est. Priority Date: 04/25/1977
• 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: Vercellotti, Leonard C., McGivern, James P., Whyte, Ian A.
• Primary Examiner(s): Caldwell, Sr., John W.
• Assistant Examiner(s): Groody, James J.
• Application Number:
  US05/959,825
• Time in Patent Office: 596 Days
• Field of Search: 340/310 R, 340/310 A, 340/310 CP, 325/21, 179/170 R, 179/170 J, 307/3, 307/149, 336/175
• US Class Current: 340/9.1
• CPC Class Codes: H04B 3/58 Repeater circuits

Abstract

A distribution network power line communication system divided into addressable communication zones defined by signal repeaters located at spaced intervals along the distribution network. The signal repeaters are switchably disposed in signal communication between the primary and grounded neutral conductors of the primary distribution network. Each repeater, when uniquely addressed by an interrogation signal from a central communication terminal, transfers the interrogation signal from the primary conductor to the primary grounded neutral conductor whereon it is transmitted to a uniquely addressed remote communication terminal coupled to a secondary neutral conductor within the communication zone of the signal repeater. A timely response signal from the remote communication terminal on the grounded neutral conductor is transferred by the repeater to the primary conductor and then to the central communication terminal. Coupling circuitry, responsive to repeater logic section control signals, connects the receiver and transmitter sections of each signal repeater to either the primary or grounded neutral conductors of the distribution network for signal amplification and bidirectional signal transmission.

Claims

1. A power line communication system, comprising:

a uniquely addressable signal repeater;

a uniquely addressable remote communication terminal;

means for providing an interrogation signal which includes the address of said signal repeater and the address of said remote communication terminal;

a first communication link including primary power line conductor means interconnecting said means for providing an interrogation signal and said signal repeater;

a second communication link including branch secondary power line conductor means distributing electric power from said primary power line conductor means and interconnecting said signal repeater with said remote communication terminal;

said remote communication terminal, when uniquely addressed by an interrogation signal over said second communication link, including means for providing a response signal on said second communication link;

said signal repeater including a first signal coupler means, disposed in signal communication with said first communication link, for communicating signals between said first communication link and said signal repeater and a second signal coupler means, disposed in signal communication with said second communication link, for communicating signals between said signal repeater and said second communication link;

said signal repeater including single means for receiving interrogation and response signals and also single means for transmitting interrogation and response signals;

said signal repeater including means for switchably connecting said single receiving means to said first signal coupler means to receive interrogation signals carried on said first communication link and to said second signal coupler means to receive response signals carried on said second communication link and, also, for switchably connecting said signal transmitting means to said second signal coupler means to transmit said interrogation signals onto said second communication link and to said first signal coupler means to transmit said response signals onto said first communication link such that said interrogation and response signals are transferred between said first and second communication links according to a predetermined sequence; and

means for receiving said response signal from said signal repeater on said first communication link.

2. The power line communication system of claim 1 wherein the first communication link includes a primary power line conductor at ground potential and the second communication link includes a secondary power line conductor at ground potential connected to the primary conductor at ground potential and wherein said second signal coupler means is disposed in signal communication with both of the primary and secondary power line conductors at ground potential adjacent a junction of said branch secondary power line conductor means and said primary power line conductor means.

3. The power line communication system of claim 1 wherein the means for switchably connecting the single receiving means and the single transmitting means of the signal repeater includes a first switch connected to said single receiving means and switchably disposed between the first and second signal coupler means and further includes a second switch connected to said single transmitting means and switchably disposed between said first and second signal coupler means.

4. The power line communication system of claim 3 wherein the signal repeater includes logic means for decoding selected bits of the interrogation and response signals and for generating, in response thereto, control signals for operably switching the first and second switches between the first and second signal coupling means such that said interrogation and response signals are transferred between said first and second communication links according to a predetermined sequence.

5. The power line communication system of claim 4 wherein the first signal coupler means includes a first conductor connected to earth ground and the second signal coupler means includes a second conductor connected to earth ground, said first signal coupler further including a first transformer element inductively coupled around said first conductor, said second signal coupler further including a second transformer element inductively coupled around said second conductor;

each of said first and second transformers having primary and secondary portions, said primary portion consisting of a hollow core of magnetic material disposed in inductive relation around said ground conductor whereby a single turn primary winding is formed, said secondary portion including wound conductors inductively coupled to said core to form first and second coupling terminations for the signal repeater, said first signal coupler further including a capacitor element connecting said first communication link to said first ground conductor.

6. The power line communication system of claim 5 wherein the first switch is switchably disposed between the first coupling terminations of the first and second transformers and the second switch is switchably disposed between the second coupling terminations of said first and second transformers.

7. The power line communication system of claim 6 wherein the logic means further includes means for comparing the repeater address contained in an interrogation signal with the unique address of the signal repeater and for generating, in response thereto, a control signal indicating whenever said addresses match.

8. The power line communication system of claim 7 further including switch control means, responsive to the control signal from the comparator means, for controlling the position of the first and second switches.

9. The power line communication system of claim 8 wherein the logic means of the repeater includes means for energizing the switch control means for a predetermined amount of time, said predetermined amount of time being sufficient for the interrogation signal to be transmitted to the remote communication terminal specified in said interrogation signal and the response signal generated thereby, to be received by said signal repeater.

10. The power line communication system of claim 9 wherein the switch control means is an electromechanical relay and the first and second switches are contacts thereof.

12. The power line communication system of claim 1 including further ones of said uniquely addressable signal repeater so as to include a plurality of the signal repeaters;

and wherein the means for switchably connecting the single receiving means and single transmitting means in each of said signal repeaters is operative to connect said single receiving means to the first signal coupler means to receive response signals on the first communication link from another one of said signal repeaters and, also, to connect said single transmitting means to said first signal coupler means to transmit interrogation signals onto said first communication link to another one of said signal repeaters.

11. A power line communication system comprising:

an electrical distribution network including primary conductors extending between a distribution substation and a plurality of distribution transformers, branch secondary conductors extending between said distribution transformers and certain electrical loads, with one of said primary and one of said secondary conductors disposed at ground potential with respect to the others of said primary and secondary conductors to form a continuous ground conductor extending between said distribution substation and each electrical load;

uniquely addressable remote communication terminals associated with certain of said electrical loads;

said remote communication terminals disposed in signal communication with said ground conductor of said distribution network;

means, disposed in signal communication with one of said primary conductors of said distribution network for generating interrogation signals containing at least the address of a repeater and remote communication terminal;

each of said remote communication terminals, upon receiving an interrogation signal, providing a response signal on said ground conductor;

uniquely addressable signal repeaters associated with certain of said remote communication terminals, each of said signal repeaters including single means for receiving and single means for transmitting interrogation and response signals, each of said signal repeaters further including first and second signal couplers, said first signal coupler including a coupling capacitor and a first conductor connected to earth ground, said coupling capacitor coupling one of said other primary conductors in signal communication with said first ground conductor, said second signal coupler including a second conductor connected to earth ground and to one of said conductors at ground potential adjacent one of said distribution transformers,

first and second transformer elements associated with said first and second ground conductors, respectively, each of said first and second transformers having primary and secondary portions;

said primary portion consisting of a hollow core of magnetic material disposed in inductive relation around one of said first or second ground conductors whereby a single turn primary winding is formed;

said secondary portion including two wound conductors inductively coupled to said core to form first and second coupling terminations;

each of said signal repeaters including at least first and second switches, said first switch being connected to said single receiving means and said second switch being connected to said single transmitting means;

said first switch switchably disposed between said first coupling terminations of said first and second transformers, said second switch switchably disposed between said second coupling terminations of said first and second transformers;

each of said signal repeaters including switch control means for operably moving said first and second switches between said coupling terminations of said first and second transformer elements; and

each of said signal repeaters further including logic means for decoding selected bits of said interrogation and response signals and for generating, in response thereto, control signals useful in operating said switch control means,

said logic means including means for comparing the address of said signal repeater with the repeater address contained in said interrogation and response signals and for generating in response thereto, a control signal whenever said addresses match;

said switch control means being responsive to said control signal from said comparing means and having a first state wherein said first and second switches are connected to said first and second coupling terminations of said first transformer element, respectively, and a second state wherein said first and second switches are connected to said first and second coupling terminations of said second transformer element, respectively.

13. The power line communication system of claim 11 wherein the logic means of each repeater includes means for holding the switch control means in the second state for a predetermined amount of time, said predetermined amount of time being sufficient for the interrogation signal to be transmitted to the remote communication terminal specified in the interrogation signal and the response signal, generated thereby, to be received by said signal repeater.

14. The power line communication system of claim 13 wherein the switch control means is an electrical relay and the first and second switches are relay contacts associated with said relay.