Inductive coupling of a data signal to a power transmission cable

• US 6,452,482 B1
• Filed: 12/28/2000
• Issued: 09/17/2002
• Est. Priority Date: 12/30/1999
• Status: Expired due to Term

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ambient S A
• Inventors: Cern, Yehuda
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US09/752,705
• Publication Number:
  US 20020105413A1
• Time in Patent Office: 628 Days
• Field of Search: 340/310.01, 340/310.03, 340/310.05, 340/310.07, 375/258, 375/259, 375/283, 324/66
• US Class Current: 375/258
• CPC Class Codes: H04B 2203/5487 cables
• CPC Class Codes: H04B 3/56 Circuits for coupling, blocking, or by-passing of signals

Abstract

There is provided an apparatus for enabling communication of a data signal via a power transmission cable. The apparatus includes (a) a first winding for coupling the data signal via a conductor of the power transmission cable, and (b) a second winding, inductively coupled to the first winding, for coupling the data signal via a data port. The apparatus further includes the power transmission cable having a first neutral conductor and a second neutral conductor and apparatus for differential coupling of the data signal to the first and second neutral conductors.

Claims

1. An apparatus for enabling communication of a data signal via a power transmission cable having a first neutral conductor and a second neutral conductor, comprising:

a core for placement about said first and second neutral conductors; and

a winding wrapped around a portion of said core,

wherein said data signal is inductively coupled between said first neutral conductor and a data port, and between said second neutral conductor and said data port, via said core and said winding, and

wherein said data signal is driven differentially through said first and second neutral conductors.

2. The apparatus of claim 1,

wherein said core induces a first current in said first neutral conductor in a first direction, and induces a second current in said second neutral conductor in a second direction that is opposite of said first direction.

3. The apparatus of claim 1, wherein said core is topographically configured as a figure “

8”

with no contact at the crossing point of the “

8”

.

4. The apparatus of claim 3,

wherein said core comprises a first region adjacent to said first neutral conductor and a second region adjacent to said second neutral conductor,

wherein said first region comprises a first loop of said figure “

8”

,

wherein said first conductor is routed through said first loop,

wherein said second region comprises a second loop of said figure “

8”

, and

wherein said second conductor is routed through said second loop.

5. The apparatus of claim 3,

wherein said core comprises a first region adjacent to said first neutral conductor and a second region adjacent to said second neutral conductor,

wherein said first region comprises a first gap in a first loop of said figure “

8”

,

wherein said first conductor is routed through said first gap,

wherein said second region comprises a second gap in a second loop of said figure “

8”

, and

wherein said second conductor is routed through said second gap.

6. The apparatus of claim 1, wherein said first neutral conductor and said second neutral conductor are substantially parallel to one another in said power transmission cable.

7. The apparatus of claim 1,

wherein said first neutral conductor is routed in a first direction through said core and connected to a grounded center tap, and

wherein said second neutral conductor is routed in a second direction through said core, and connected to said grounded center tap.

8. The apparatus of claim 1,

wherein said power transmission cable has a plurality of neutral wires that are substantially parallel to one another, with individuals of a first subset of said plurality of neutral conductors alternating with individuals of a second subset of said plurality of neutral conductors,

wherein said first neutral conductor comprises said first subset of said plurality of neutral conductors, and

wherein said second neutral conductor comprises said second subset of said plurality of neutral conductors.

9. The apparatus of claim 1, further comprising

a magnetic toroid disposed around a portion of said power transmission cable,

wherein said first neutral conductor and said second neutral conductor are connected to a common terminating member downstream of said magnetic toroid, and

wherein said core is placed about said first and second neutral conductors upstream of said magnetic toroid.

10. The apparatus of claim 1,

wherein said core comprises an open magnetic core having:

a first leg positioned proximate and perpendicular to said first neutral conductor;

a second leg positioned proximate and perpendicular to said second neutral conductor; and

a third leg, located between said first leg and said second leg, having said winding wound thereabout.

11. The apparatus of claim 1,

wherein said core comprises a first magnetic toroidal core having a gap through which said first neutral conductor s routed and a second magnetic toroidal core having a gap through which said second neutral conductor is routed, and

wherein said winding is wound around a portion of said first magnetic toroidal core and a portion of said second magnetic toroidal core.

12. The apparatus of claim 1, further comprising:

a first modem having a first port coupled to said data port, and having a second port for further coupling of said data signal; and

a second modem having a first port coupled to said second port of said first modem, and having a second port for further coupling of said data signal.

13. The apparatus of claim 12, wherein said first modem and said second modem are configured back-to back.

14. The apparatus of claim 12, further comprising a data router interposed between said first modem and said second modem.

15. A data communication network implemented over a power distribution system having a power transmission cable with a first conductor for a phase on a primary side of a transformer and a second conductor for a phase on a secondary side of the transformer, said data communication network comprising:

a first coupler for inductively coupling a data signal via said first conductor and;

a second coupler for coupling said data signal via said second conductor,

wherein said data signal is coupled between said first conductor and said second conductor via said first coupler and said second coupler, thus bypassing said transformer.

16. The data communication network of claim 15,

wherein said data communication network further comprises a capacitor for coupling said data signal between said second coupler and said second conductor.

17. The data communication network of claim 15, wherein said first conductor is part of a medium voltage grid of said power distribution system.

18. The data communication network of claim 15, further comprising a capacitive coupler, connected between said first conductor and a ground, proximate to an end of said power transmission cable, for absorbing reflections of said data signal, wherein said end of said power transmission cable is at a medium voltage output terminal of a high voltage to medium voltage transformer of said power distribution system.

19. The data communication network of claim 15, further comprising:

a capacitive coupler, connected between said first conductor and a ground, proximate to an end of said power transmission cable, for absorbing reflections of said data signal; and

a node, located between said capacitive coupler and said ground, for coupling said data signal between said first conductor and a data port.

20. The data communication network of claim 15, wherein said first coupler comprises:

a core through which said first conductor is routed, and

a winding wound around a portion of said core,

wherein said data signal is inductively coupled via said first conductor through said core and said winding.

21. The data communication network of claim 20, wherein said core has an air gap.

22. The data communication network of claim 20, further comprising a capacitor in series with said winding.

23. The data communication network of claim 20, further comprising a surge protector connected in parallel with said winding.

24. The data communication network of claim 15, further comprising a capacitive coupler, connected between said first conductor and a ground, proximate to an end of said power transmission cable, for absorbing reflections of said data signal, wherein said capacitive coupler comprises:

a capacitor;

a high frequency isolation transformer;

a fuse;

a bleeder resistor; and

a termination resistor having a resistance approximately equal to a characteristic impedance of said power transmission cable.

25. The data communication network of claim 15, further comprising:

a first modem having a first port for coupling said data signal via said first coupler, and having a second port for further coupling of said data signal; and

a second modem having a first port coupled to said second port of said first modem, and having a second port for coupling of said data signal via said second coupler.

26. The data communication network of claim 15, wherein said first coupler comprises a radio frequency (RF) transformer.

27. The data communication network of claim 15,

wherein said transformer comprises a voltage step-down transformer, and

wherein said data communication network further comprises:

a capacitive coupler, connected between said second conductor and a ground; and

a component having an impedance that when reflected through said capacitive coupler is approximately equal to a characteristic impedance of said power transmission cable.

28. The data communication network of claim 27, wherein said component is a modem.

29. The data communication network of claim 15,

wherein said power distribution system includes a transition between an overhead cable and an underground cable,

wherein said underground cable has a characteristic impedance that is lower than that of said overhead cable, and

wherein said first coupler is located on said overhead cable, proximate to said transition.

30. The data communication network of claim 15,

wherein said power distribution system includes a component between said first conductor and a ground,

wherein said component has an impedance of less than that of said power transmission cable, and

wherein said data communication network further comprises a choke in series with said component.

31. The data communication network of claim 30, wherein said component is selected from the group consisting of a power factor correction capacitor, and a power line communications (PLC) capacitor.

32. The data communication network of claim 30, wherein said choke comprises a magnetic core disposed around a length of a wire that connects said component to said first conductor.

33. The data communication network of claim 15, further comprising:

a first modem having a first port for coupling said data signal via said first coupler, and having a second port for further coupling of said data signal;

a router having a first port for coupling said data signal via said second port of said first modem and having a second port for further coupling of said data signal; and

a second modem having a first port coupled to said second port of said router, and having a second port for coupling said data signal via said second coupler.

34. A data communication network implemented over a power distribution system having a phase conductor with a first segment on a first side of a switch and a second segment on a second side of said switch, comprising:

a first capacitive coupler for coupling a data signal via said first segment, and having a data port for further coupling of said data signal; and

a second capacitive coupler having a data port coupled to said data port of said first capacitive coupler, and for coupling said data signal via said second segment,

wherein a transmission of said data signal between said first segment and said second segment is maintained when said switch is opened.

35. A method for enabling communication of a data signal via a power transmission cable having a first neutral conductor and a second neutral conductor, said method comprising arranging an apparatus for differential coupling of said data signal to said first and second neutral conductors.

36. A method for enabling communication of a data signal over a power distribution system having a power transmission cable with a first conductor for a phase on a primary side of a transformer and a second conductor for a phase on a secondary side of the transformer, said method comprising:

arranging a first coupler for inductively coupling said data signal via said first conductor; and

arranging a second coupler for coupling said data signal via said second conductor,

wherein said data signal is coupled between said first conductor and said second conductor via said first coupler and said second coupler, thus bypassing said transformer.