Body capacitance electric field powered device for high voltage lines

• US 7,902,854 B2
• Filed: 07/22/2004
• Issued: 03/08/2011
• Est. Priority Date: 07/25/2003
• Status: Expired due to Fees

• Current Assignee: Power Measurement Ltd. (Schneider Electric SE)
• Original Assignee: Power Measurement Ltd. (Schneider Electric SE)
• Inventors: Forth, John Bradford, Gunn, Colin, Hyatt, Geoffrey T., Hancock, Martin A., Lightbody, Simon H.
• Primary Examiner(s): Nguyen; Ha Tran T
• Assistant Examiner(s): Nguyen; Tung X
• Application Number:
  US10/566,007
• Publication Number:
  US 20080246507A1
• Time in Patent Office: 2,420 Days
• Field of Search: 324/126, 324/127, 324/142, 324/763, 324/765, 324/771, 324/158.1, 340/870.17
• US Class Current: 324/754.01
• CPC Class Codes: G01R 1/22 Tong testers acting as secondary windings of current transformers
• CPC Class Codes: G01R 15/14 Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
• CPC Class Codes: H02G 7/00 Overhead installations of electric lines or cables installations of bus-bars H02G5/00
• CPC Class Codes: H02G 7/14 Arrangements or devices for damping mechanical oscillations of lines, e.g. for reducing production of sound damping spacers H02G7/125

Abstract

Devices that couple to high voltage transmission lines obtain power themselves using the body capacitance of an element of the devices. The devices generate a comparatively lower voltage from the current flowing between the high voltage line and the element of the device that generates the body capacitance. The devices can be used to operate sensors that monitor the transmission lines or parameters of the power distribution system, such as current, line temperature, vibration, and the like. The devices can also be used as indicators, such as aircraft warning lights, information signs, etc. In addition, the devices can operate as RF transmission/reception or repeater devices, radar devices, mesh networking nodes, video/audio surveillance, sound emitting devices for scaring animals, drones that traverse the power line, etc. Because the devices operate in response to line voltage rather than current, the devices are reliable even in low current conditions.

Claims

1. An apparatus for mounting coupled with a power line carrying a high AC line voltage, the apparatus comprising:

a conductive body having a body capacitance;

a power supply comprising at least two input terminals;

a first of said at least two input terminals coupled to said conductive body and a second of said at least two input terminals operative to be coupled to said power line;

electronic circuitry coupled to said power line comprising;

a voltage sensor operative to sense voltage on said power line, said voltage sensor having a metallic plate operative to form a first capacitance with an external reference;

a second capacitance coupled between said metallic plate and a system reference; and

detection circuitry operative to detect the voltage level on said metallic plate;

wherein said power supply is operative to convert power flow between said conductive body and said power line into a supply of power at a voltage substantially lower than said high AC line voltage for operation of said electronic circuitry.

2. The apparatus of claim 1, wherein said electronic circuitry comprises:

a sensor operative to sense at least one parameter, said at least one parameter comprises at least one of ambient temperature, internal temperature, temperature of said power line, strain, humidity, elevation, position, ambient light level, air quality, vibration, acceleration, sound level or atmospheric pressure.

3. The apparatus of claim 2, wherein said electronic circuitry further comprises a wireless radio frequency transmitter operative to transmit said at least one parameter to a remote device which is not physically coupled to said apparatus.

4. The apparatus of claim 3, wherein said electronic circuitry further comprises a radio frequency positioning receiver operative to receive position information and determine the position of said apparatus.

5. The apparatus of claim 3, wherein:

said electronic circuitry further comprises a processor operative to secure data incorporating said at least one parameter; and

said wireless radio frequency transmitter is operative to transmit said data.

6. The apparatus of claim 1, wherein said electronic circuitry comprises a current sensor operative to sense current flow in said power line.

7. The apparatus of claim 6, wherein said current sensor comprises at least one of an active current transformer, a Hall effect sensor, a Rogowski coil, a magnetic core current transformer and an optical current transducer.

8. The apparatus of claim 6, further comprising:

at least one analog to digital converter coupled to said current sensor;

a processor coupled to said at least one analog to digital converter and operative to receive digital samples representative of said current flow in said power line from said analog to digital converter, and

a wireless radio frequency transmitter coupled to said processor and operative to transmit said digital samples to a remote device which is not physically coupled to said apparatus.

9. The apparatus of claim 8, further comprising:

time synchronization receiver coupled to said processor; and

wherein said processor is operative to associate at least one timestamp from said time synchronization receiver with said digital samples.

10. The apparatus of claim 1, wherein said detection circuitry comprises:

an amplifier operative to buffer said voltage level; and

an analog to digital converter operative to generate a digital representation of said voltage level.

11. The apparatus of claim 1, further comprising a high value resistor coupled between said metallic plate and a DC voltage rail and operative to maintain said metallic plate at a fixed DC voltage with respect to said system reference.

12. The apparatus of claim 11, further comprising a surge arrestor coupled to said metallic plate.

13. The apparatus of claim 1, further comprising:

an electric conductor extending from said metallic plate to said second capacitance; and

an insulator surrounding at least a portion of said electric conductor, supporting said metallic plate and preventing electric conductivity between said metallic plate and said conductive body.

14. The apparatus of any of claim 1, wherein said second capacitance comprises:

a bank of parallel capacitors, each of said capacitors operative to be dynamically electrically coupled and decoupled between said metallic plate and said system reference in order to form a variable capacitive divider; and

a processor operative to control the coupling of said bank of parallel capacitors and calculate the voltage on said power line using a plurality of said voltage levels when said second capacitance is switched to a plurality of values.

15. The apparatus of claim 14, further comprising:

a conductive partition operative to prevent electric fields generated within said apparatus from affecting the voltage on said metallic plate and separate said apparatus into at least a first and second chamber, said first chamber housing at least said metallic plate and said second chamber housing at least a portion of said electronic circuitry; and

a dielectric cover formed at an outside end of said second chamber and operative to protect said metallic plate from the environment.

16. The apparatus of claim 1, wherein said external reference comprises ground.

17. The apparatus of claim 1, wherein said external reference comprises a second power line.

18. The apparatus of claim 1, wherein said electronic circuitry comprises:

at least one analog to digital converter coupled to said voltage sensor and said current sensor; and

a processor coupled to said at least one analog to digital converter and operative to receive digital samples representative of said current flow in said power line and said voltage on said power line from said analog to digital converter.

19. The apparatus of claim 18, wherein said processor is operative to produce power flow data indicative of power flow in said power line using said digital samples.

20. The apparatus of claim 1, wherein said electronic circuitry comprises at least one light source and at least one processor operative to control the lighting of said light source.

21. The apparatus of claim 19, wherein said electronic circuitry further comprises a light sensor operative to sense ambient lighting conditions in the vicinity of said apparatus.

22. The apparatus of claim 21, wherein said processor is coupled to said light sensor and said light source;

said processor operative to illuminate said light source when said light sensor indicates said ambient lighting conditions are below a threshold.

23. The apparatus of claim 1, further comprising an energy storage device coupled to said power supply and operative to supply power to said electronic circuitry when a condition exists such that said electronic circuitry demands more power than said power supply can produce.

25. The apparatus of claim 18, wherein said processor controls the application of charge to said energy storage device.

26. The apparatus of claim 1, wherein said power supply comprises a transformer having at least a primary and a secondary winding, wherein said primary winding has a greater number of turns than said secondary winding.

27. The apparatus of claim 1, wherein said power supply comprises:

a capacitor;

a rectification circuit coupled to said capacitor and operative to allow said capacitor to charge to a DC voltage from said power flow;

a controller operative to prevent and allow the flow of current through said primary winding from said capacitor;

a filter circuit coupled to said secondary winding and operative to produce said voltage substantially lower than said high AC line voltage; and

a feedback circuit coupled to said filter circuit and said controller wherein said controller uses the output of said feedback circuit to modulate said prevention and allowance of current flow in order to regulate said voltage substantially lower than said high AC line voltage.

28. The apparatus of claim 1, wherein said electronic circuitry further comprises an electric motor operative to propel said apparatus along said power line.

29. The apparatus of claim 1, wherein said electronic circuitry comprises at least one of a radar transmitter, fiber optic transmitter, a power line carrier transceiver, a display, a mesh networking transceiver, a sound emitting device, a video surveillance device, an audio surveillance device, a radio frequency repeater, an information sign and an advertising sign.

30. The apparatus of claim 1, wherein said electronic circuitry comprises time synchronization reception circuitry operative to provide an indication of time to said processor;

said processor operative to control said lighting based on said indication of time.

31. The apparatus of claim 26, wherein said power supply comprises:

a rectification circuit coupled across said secondary winding;

a capacitor coupled to the output of said rectification circuit and operative to produce a DC voltage substantially lower than said high AC line voltage;

a regulator coupled to said capacitor and operative to regulate said DC voltage substantially lower than said high AC line voltage; and

wherein said primary winding is coupled in series between said conductive body and said power line.

24. The apparatus of 23, wherein said condition is the illumination of said light source and/or failure of said high AC line voltage.