Power Line Communications Coupling Device and Method
A method and device for providing communications via one or more underground power lines is provided. Underground power lines may comprise a plurality of segments disposed in series with each other and carrying a power having a voltage greater than one thousand volts on an internal conductor, and wherein each segment is coaxial in structure and includes a neutral conductor. In one embodiment, the device may comprise a first inductor having a first end connected to a first node and a second end connected to ground, a second inductor having a first end connected a second node and a second end connected to ground, and a transformer having a first winding having a first end and a second end. The first node may be connected to a neutral conductor of a first segment of the power line and to the first end of the first winding of said transformer. The second node may be connected to a neutral conductor of a second segment of the power line and to the second end of the first winding of said transformer. The transformer comprises a second winding configured to be communicatively coupled to a communication device.
1 . A device for providing communications via an underground power line comprising a plurality of segments disposed in series with each other and carrying power having a voltage greater than one thousand volts on an internal conductor, wherein each segment is coaxial in structure and includes a neutral conductor, comprising:
a first inductor having a first end connected to a first node and a second end connected to ground;
a second inductor having a first end connected a second node and a second end connected to ground;
a transformer having a first winding having a first end and a second end;
wherein said first node is connected to a neutral conductor of a first segment of the power line and to said first end of said first winding of said transformer;
wherein said second node is connected to a neutral conductor of a second segment of the power line and to said second end of said first winding of said transformer; and
wherein said transformer comprises a second winding configured to be communicatively coupled to a communication device.
2 . The device according to claim 1 , further comprising:
a first voltage clamping device connected in parallel with said first inductor; and
a second voltage clamping device connected in parallel with said second inductor.
3 . The device according to claim 1 , wherein said first inductor comprises a first air core coil and said second inductor comprises a second air core coil.
4 . The device according to claim 1 , wherein said first inductor and said second inductor each comprises a coil having a plurality of loops having a substantially rectangular cross section and being separated from each other loop by a dielectric.
5 . The device according to claim 1 , further comprising:
a first magnetically permeable toroid disposed substantially around the entire circumference of the first segment of the power line; and
a second magnetically permeable toroid disposed substantially around the entire circumference of the second segment of the power line.
6 . A method of providing communications via one or more underground power lines, each comprising a plurality of segments disposed in series with each other and carrying power having a voltage greater than one thousand volts on an internal conductor, wherein each segment is coaxial in structure and includes a neutral conductor, comprising:
conducting a first signal along a first communication path from a communication device to a neutral conductor of a first segment;
conducting a second signal along a second communication path from the communication device to a neutral conductor of a second segment; and
wherein the first signal and second signal represent the same data and are substantially the same magnitude and opposite in polarity.
7 . The method according to claim 6 , further comprising:
providing a first high frequency impedance path between the first communication path and ground; and
providing a second high frequency impedance path between the second communication path and ground.
8 . The method according to claim 7 , further comprising:
providing a first voltage clamping device disposed in parallel with said first high frequency impedance path; and
providing a second voltage clamping device disposed in parallel with said second high frequency impedance path.
9 . The method according to claim 7 , wherein the first and second high frequency impedance path each comprises a conductor having a magnetically permeable material disposed substantially around the entire circumference of the conductor.
10 . The method according to claim 7 , wherein the first and second high frequency impedance path each comprises a coil having a plurality of loops having a substantially rectangular cross section and being separated from each other loop by a dielectric.
11 . The method according to claim 6 , wherein:
the first signal is conducted from a first end of a first winding of a balun along the first communication path to the neutral conductor of the first segment; and
the second signal is conducted from a second end of the first winding of the balun along the second communication path to the neutral conductor of the second segment.
12 . The method according to claim 6 , further comprising:
providing a first magnetically permeable toroid substantially around the entire circumference of the first segment; and
providing a second magnetically permeable toroid substantially around the entire circumference of the second segment.
13 . A device for providing communications via one or more underground power lines, each comprising a plurality of segments disposed in series with each other and carrying power having a voltage greater than one thousand volts on an internal conductor, wherein each segment is coaxial in structure and includes a neutral conductor, comprising:
a first high frequency impedance having a first end connected to a neutral conductor of a first segment of a power line and a second end connected to ground;
a second high frequency impedance having a first end connected to a neutral conductor of a second segment of the power line and a second end connected to ground; and
a communication device having a first terminal communicatively coupled to said first end of said first high frequency impedance and having a second terminal communicatively coupled to said first end of said second high frequency impedance.
14 . The device according to claim 13 , wherein said first terminal is communicatively coupled to said first end of said first high frequency impedance via a balun and said second terminal is communicatively coupled to said first end of said second high frequency impedance via said balun.
15 . The device according to claim 13 , further comprising:
a first magnetically permeable toroid disposed around the circumference of the first segment of the power line; and
a second magnetically permeable toroid disposed around the circumference of the second segment of the power line.
16 . The device according to claim 13 , further comprising:
a first voltage clamping device disposed in parallel with said first high frequency impedance; and
a second voltage clamping device disposed in parallel with said second high frequency impedance.
17 . The device according to claim 13 , wherein said first high frequency impedance comprises a first air core coil and said second high frequency impedance comprises a second air core coil.
18 . The device according to claim 13 , wherein said first high frequency impedance and said second high frequency impedance each comprises a coil having a plurality of loops having a substantially rectangular cross section and being separated from each other loop by a dielectric.
19 . A device for providing communications via an underground power line carrying power having a voltage greater than one thousand volts on an internal conductor, the power line being coaxial in structure and having a neutral conductor, comprising:
a high frequency impedance having a first end connected to a first node;
wherein said first node is connected to the neutral conductor of the power line and to a communication device; and
a capacitor having a first terminal connected to the internal conductor of the power line and having a second terminal connected to ground.
20 . The device according to claim 19 , wherein said high frequency impedance comprises an air core coil.
21 . The device according to claim 19 , wherein said high frequency impedance comprises a conductor having a magnetically permeable material disposed substantially around the entire circumference of said conductor.
22 . The device according to claim 19 , wherein said high frequency impedance comprises a coil having a plurality of loops having a substantially rectangular cross section and being separated from each other loop by a dielectric.
23 . The device according to claim 19 , wherein said capacitor comprises a lightening arrestor.
24 . The device according to claim 19 , further comprising a voltage clamping device connected in parallel with said high frequency impedance.
25 . A device for providing communications via one or more underground power lines, each comprising a plurality of segments disposed in series with each other and carrying power having a voltage greater than one thousand volts on an internal conductor, wherein each segment is coaxial in structure and includes a neutral conductor, comprising:
a first conductor having a first end coupled to a first neutral conductor of a first segment and a second end configured to be connected to a first terminal of a transmitter;
a second conductor having a first end coupled to a second neutral conductor of a second segment and having a second end configured to be connected to a second terminal of the transmitter;
a first impedance forming a conductive path between said first conductor and ground;
a second impedance forming a conductive path between said second conductor and ground; and
wherein the transmitter is configured to differentially apply communication signals to the first and second neutral conductors via said first conductor and said second conductor.