Apparatus and methods for power network coupling

• US 5,933,073 A
• Filed: 07/07/1997
• Issued: 08/03/1999
• Est. Priority Date: 07/07/1997
• Status: Expired due to Term

• Current Assignee: ABB Power T&D Limited (ABB Limited)
• Original Assignee: ABB Power T&D Limited (ABB Limited)
• Inventors: Shuey, Kenneth C.
• Primary Examiner(s): Lefkowitz, Edward
• Assistant Examiner(s): GOINS, DAVETTA WOODS
• Application Number:
  US08/888,773
• Time in Patent Office: 757 Days
• Field of Search: 340/310.01, 340/310.05, 340/310.06, 340/310.07, 340/310.03
• US Class Current: 375/258
• CPC Class Codes: H04B 2203/5408 using protocols
• CPC Class Codes: H04B 2203/5425 improving S/N by matching impedance, noise reduction, gain control
• CPC Class Codes: H04B 2203/5445 Local network
• CPC Class Codes: H04B 2203/5458 Monitor sensor; Alarm systems
• CPC Class Codes: H04B 2203/5483 using coupling circuits
• CPC Class Codes: H04B 2203/5491 using filtering and bypassing
• CPC Class Codes: H04B 3/56 Circuits for coupling, blocking, or by-passing of signals

Abstract

Methods and apparatus for establishing communications between electrical and electronic devices utilizing existing power signal distribution networks are disclosed. In such methods and apparatus the transmitting and receiving components of such devices are coupled between line and ground. Such coupling is achieved utilizing a coupler, a first frequency reactive device, such as a drain coil or inductor, connected in series with neutral and a second frequency reactive device, such as a capacitor connected between neutral ground. For use with existing electronic equipment, an adaptor for coupling the communications signal to a power signal distribution network is also disclosed. Since, line and neutral paths may sometimes be mis-wired, the apparatus and methods also disclose the use of a switch for enabling the coupling of a communication signal when a power signal is sensed on the line path.

Claims

1. Apparatus for coupling a communications signal to a power signal distribution network, said network comprising line, ground and neutral paths, said apparatus comprising, a coupler for coupling said communication signal between said line and ground paths, a switch connected to said coupler for enabling said coupler when a power signal is applied to said line path, and a first frequency reactive device, connected in series with said neutral path, wherein the impedance of said first frequency reactive device increases as the frequency of a signal applied to said first frequency reactive device increases.

2. The apparatus of claim 1, wherein said first frequency reactive device comprises a drain coil, connected in series with said neutral path.

3. The apparatus of claim 1, wherein said first frequency reactive device comprises an inductor, connected in series with said neutral path.

4. The apparatus of claim 1, further comprising a second frequency reactive device, connected between said neutral path and said ground path, wherein the impedance of said second frequency reactive device decreases as the frequency of a signal applied to said second frequency reactive device increases.

5. The apparatus of claim 4, wherein said second frequency reactive device comprises a capacitor.

6. An adaptor for coupling a communications signal to a power signal distribution network, said network comprising line, ground and neutral paths, said adaptor comprising:

a first frequency reactive device, connected in series with said neutral path, wherein the impedance of said first frequency reactive device increases as the frequency of a signal applied to said first frequency reactive device increases;

a second frequency reactive device, connected between said neutral path and said ground path, wherein the impedance of said second frequency reactive device decreases as the frequency of a signal applied to said second frequency reactive device increases; and

a switch, connected to said second frequency reactive device, for enabling said second frequency reactive device when a power signal is applied to line path.

7. The adaptor of claim 6, wherein said first frequency reactive device comprises an inductor, connected in series with said neutral path.

8. The adaptor of claim 6, wherein said second frequency reactive device comprises a capacitor.

9. The adaptor of claim 6, wherein said switch comprises a transistor.

10. The adaptor of claim 9, wherein said transistor comprises a MOSFET and wherein the drain-source portion of said MOSFET is connected in series with said second frequency reactive device.

11. The adaptor of claim 10, wherein the gate of said MOSFET is electrically connected to said line path.

12. The adaptor of claim 11, further comprising a resistor and a capacitor connected to each other in parallel and connected to said line path and connected to the gate of said MOSFET, so that the charge on said gate is maintained.

13. A method for coupling a communications signal to a power signal distribution network, said network comprising line ground and neutral paths, said method comprising the steps of:

sensing the presence of a power signal on said line path;

transmitting said communication signal on said line and ground paths when a power signal is sensed on said line path; and

blocking the transmission of said communication signal on said neutral path.

14. The method of claim 13, wherein the step of transmitting comprises the step of connecting a coupler, for coupling said communication signal, between said line and ground paths and connecting a first frequency reactive device to said neutral path, wherein the impedance of said first frequency reactive device increases as the frequency of a signal applied to said first frequency reactive device increases.

15. The method of claim 14, wherein said step of connecting a first frequency reactive device comprises the step of connecting an inductor in series with said neutral path.

16. The method of claim 13, further comprising the step of connecting a second frequency reactive device between said neutral path and said ground path, wherein the impedance of said second frequency reactive device decreases as the frequency of a signal applied to said second frequency reactive device increases.

17. The method of claim 16, wherein said step of connecting a second frequency reactive device comprises the step of connecting a capacitor between said neutral path and said ground path.

18. The method of claim 13, further comprising the step of disabling the transmission of said communication signal on said line and ground paths when a power signal is not sensed on said line path.